Yesterday’s piece told the tale of Hieu Minh Ngo, a hacker the U.S. Secret Service described as someone who caused more material financial harm to more Americans than any other convicted cybercriminal. Ngo was recently deported back to his home country after serving more than seven years in prison for running multiple identity theft services. He now says he wants to use his experience to convince other cybercriminals to use their skills for good. Here’s a look at what happened after he got busted.

Part I of this series ended with Ngo in handcuffs after disembarking a flight from his native Vietnam to Guam, where he believed he was going to meet another cybercriminal who’d promised to hook him up with the mother of all consumer data caches.

Ngo had been making more than $125,000 a month reselling ill-gotten access to some of the biggest data brokers on the planet. But the Secret Service discovered his various accounts at these data brokers and had them shut down one by one. Ngo became obsessed with restarting his business and maintaining his previous income. By this time, his ID theft services had earned roughly USD $3 million.

As this was going on, Secret Service agents used an intermediary to trick Ngo into thinking he’d trodden on the turf of another cybercriminal. From Part I:

The Secret Service contacted Ngo through an intermediary in the United Kingdom — a known, convicted cybercriminal who agreed to play along. The U.K.-based collaborator told Ngo he had personally shut down Ngo’s access to Experian because he had been there first and Ngo was interfering with his business.

“The U.K. guy told Ngo, ‘Hey, you’re treading on my turf, and I decided to lock you out. But as long as you’re paying a vig through me, your access won’t go away’,” the Secret Service’s Matt O’Neill recalled.

After several months of conversing with his apparent U.K.-based tormentor, Ngo agreed to meet him in Guam to finalize the deal. But immediately after stepping off of the plane in Guam, he was apprehended by Secret Service agents.

“One of the names of his identity theft services was findget[.]me,” O’Neill said. “We took that seriously, and we did like he asked.”

In an interview with KrebsOnSecurity, Ngo said he spent about two months in a Guam jail awaiting transfer to the United States. A month passed before he was allowed a 10 minute phone call to his family and explain what he’d gotten himself into.

“This was a very tough time,” Ngo said. “They were so sad and they were crying a lot.”

First stop on his prosecution tour was New Jersey, where he ultimately pleaded guilty to hacking into MicroBilt, the first of several data brokers whose consumer databases would power different iterations of his identity theft service over the years.

Next came New Hampshire, where another guilty plea forced him to testify in three different trials against identity thieves who had used his services for years. Among them was Lance Ealy, a serial ID thief from Dayton, Ohio who used Ngo’s service to purchase more than 350 “fullz” — a term used to describe a package of everything one would need to steal someone’s identity, including their Social Security number, mother’s maiden name, birth date, address, phone number, email address, bank account information and passwords.

Ealy used Ngo’s service primarily to conduct tax refund fraud with the U.S. Internal Revenue Service (IRS), claiming huge refunds in the names of ID theft victims who first learned of the fraud when they went to file their taxes and found someone else had beat them to it.

Ngo’s cooperation with the government ultimately led to 20 arrests, with a dozen of those defendants lured into the open by O’Neill and other Secret Service agents posing as Ngo.

The Secret Service had difficulty pinning down the exact amount of financial damage inflicted by Ngo’s various ID theft services over the years, primarily because those services only kept records of what customers searched for — not which records they purchased.

But based on the records they did have, the government estimated that Ngo’s service enabled approximately $1.1 billion in new account fraud at banks and retailers throughout the United States, and roughly $64 million in tax refund fraud with the states and the IRS.

“We interviewed a number of Ngo’s customers, who were pretty open about why they were using his services,” O’Neill said. “Many of them told us the same thing: Buying identities was so much better for them than stolen payment card data, because card data could be used once or twice before it was no good to them anymore. But identities could be used over and over again for years.”

O’Neill said he still marvels at the fact that Ngo’s name is practically unknown when compared to the world’s most infamous credit card thieves, some of whom were responsible for stealing hundreds of millions of cards from big box retail merchants.

“I don’t know of anyone who has come close to causing more material harm than Ngo did to the average American,” O’Neill said. “But most people have probably never heard of him.”

Ngo said he wasn’t surprised that his services were responsible for so much financial damage. But he was utterly unprepared to hear about the human toll. Throughout the court proceedings, Ngo sat through story after dreadful story of how his work had ruined the financial lives of people harmed by his services.

“When I was running the service, I didn’t really care because I didn’t know my customers and I didn’t know much about what they were doing with it,” Ngo said. “But during my case, the federal court received like 13,000 letters from victims who complained they lost their houses, jobs, or could no longer afford to buy a home or maintain their financial life because of me. That made me feel really bad, and I realized I’d been a terrible person.”

Even as he bounced from one federal detention facility to the next, Ngo always seemed to encounter ID theft victims wherever he went, including prison guards, healthcare workers and counselors.

“When I was in jail at Beaumont, Texas I talked to one of the correctional officers there who shared with me a story about her friend who lost her identity and then lost everything after that,” Ngo recalled. “Her whole life fell apart. I don’t know if that lady was one of my victims, but that story made me feel sick. I know now that was I was doing was just evil.”

The Vietnamese hacker was released from prison a few months ago, and is now finishing up a mandatory three-week COVID-19 quarantine in a government-run facility near Ho Chi Minh city. In the final months of his detention, Ngo started reading everything he could get his hands on about computer and Internet security, and even authored a lengthy guide written for the average Internet user with advice about how to avoid getting hacked or becoming the victim of identity theft.

Ngo said while he would like to one day get a job working in some cybersecurity role, he’s in no hurry to do so. He’s already had at least one job offer in Vietnam, but he turned it down. He says he’s not ready to work yet, but is looking forward to spending time with his family — and specifically with his dad, who was recently diagnosed with Stage 4 cancer.

Longer term, Ngo says, he wants to mentor young people and help guide them on the right path, and away from cybercrime. He’s been brutally honest about his crimes and the destruction he’s caused. His LinkedIn profile states up front that he’s a convicted cybercriminal.

“I hope my work can help to change the minds of somebody, and if at least one person can change and turn to do good, I’m happy,” Ngo said. “It’s time for me to do something right, to give back to the world, because I know I can do something like this.”

Still, the recidivism rate among cybercriminals tends to be extremely high, and it would be easy for him to slip back into his old ways. After all, few people know as well as he does how best to exploit access to identity data.

O’Neill said he believes Ngo probably will keep his nose clean. But he added that Ngo’s service if it existed today probably would be even more successful and lucrative given the sheer number of scammers involved in using stolen identity data to defraud states and the federal government out of pandemic assistance loans and unemployment insurance benefits.

“It doesn’t appear he’s looking to get back into that life of crime,” O’Neill said. “But I firmly believe the people doing fraudulent small business loans and unemployment claims cut their teeth on his website. He was definitely the new coin of the realm.”

Ngo maintains he has zero interest in doing anything that might send him back to prison.

“Prison is a difficult place, but it gave me time to think about my life and my choices,” he said. “I am committing myself to do good and be better every day. I now know that money is just a part of life. It’s not everything and it can’t bring you true happiness. I hope those cybercriminals out there can learn from my experience. I hope they stop what they are doing and instead use their skills to help make the world better.”

At the height of his cybercriminal career, the hacker known as “Hieupc” was earning $125,000 a month running a bustling identity theft service that siphoned consumer dossiers from some of the world’s top data brokers. That is, until his greed and ambition played straight into an elaborate snare set by the U.S. Secret Service. Now, after more than seven years in prison Hieupc is back in his home country and hoping to convince other would-be cybercrooks to use their computer skills for good.

For several years beginning around 2010, a lone teenager in Vietnam named Hieu Minh Ngo ran one of the Internet’s most profitable and popular services for selling “fullz,” stolen identity records that included a consumer’s name, date of birth, Social Security number and email and physical address.

Ngo got his treasure trove of consumer data by hacking and social engineering his way into a string of major data brokers. By the time the Secret Service caught up with him in 2013, he’d made over $3 million selling fullz data to identity thieves and organized crime rings operating throughout the United States.

Matt O’Neill is the Secret Service agent who in February 2013 successfully executed a scheme to lure Ngo out of Vietnam and into Guam, where the young hacker was arrested and sent to the mainland U.S. to face prosecution. O’Neill now heads the agency’s Global Investigative Operations Center, which supports investigations into transnational organized criminal groups.

O’Neill said he opened the investigation into Ngo’s identity theft business after reading about it in a 2011 KrebsOnSecurity story, “How Much is Your Identity Worth?” According to O’Neill, what’s remarkable about Ngo is that to this day his name is virtually unknown among the pantheon of infamous convicted cybercriminals, the majority of whom were busted for trafficking in huge quantities of stolen credit cards.

Ngo’s businesses enabled an entire generation of cybercriminals to commit an estimated $1 billion worth of new account fraud, and to sully the credit histories of countless Americans in the process.

“I don’t know of any other cybercriminal who has caused more material financial harm to more Americans than Ngo,” O’Neill told KrebsOnSecurity. “He was selling the personal information on more than 200 million Americans and allowing anyone to buy it for pennies apiece.”

Freshly released from the U.S. prison system and deported back to Vietnam, Ngo is currently finishing up a mandatory three-week COVID-19 quarantine at a government-run facility. He contacted KrebsOnSecurity from inside this facility with the stated aim of telling his little-known story, and to warn others away from following in his footsteps.

BEGINNINGS

Ten years ago, then 19-year-old hacker Ngo was a regular on the Vietnamese-language computer hacking forums. Ngo says he came from a middle-class family that owned an electronics store, and that his parents bought him a computer when he was around 12 years old. From then on out, he was hooked.

In his late teens, he traveled to New Zealand to study English at a university there. By that time, he was already an administrator of several dark web hacker forums, and between his studies he discovered a vulnerability in the school’s network that exposed payment card data.

“I did contact the IT technician there to fix it, but nobody cared so I hacked the whole system,” Ngo recalled. “Then I used the same vulnerability to hack other websites. I was stealing lots of credit cards.”

Ngo said he decided to use the card data to buy concert and event tickets from Ticketmaster, and then sell the tickets at a New Zealand auction site called TradeMe. The university later learned of the intrusion and Ngo’s role in it, and the Auckland police got involved. Ngo’s travel visa was not renewed after his first semester ended, and in retribution he attacked the university’s site, shutting it down for at least two days.

Ngo said he started taking classes again back in Vietnam, but soon found he was spending most of his time on cybercrime forums.

“I went from hacking for fun to hacking for profits when I saw how easy it was to make money stealing customer databases,” Ngo said. “I was hanging out with some of my friends from the underground forums and we talked about planning a new criminal activity.”

“My friends said doing credit cards and bank information is very dangerous, so I started thinking about selling identities,” Ngo continued. “At first I thought well, it’s just information, maybe it’s not that bad because it’s not related to bank accounts directly. But I was wrong, and the money I started making very fast just blinded me to a lot of things.”

MICROBILT

His first big target was a consumer credit reporting company in New Jersey called MicroBilt.

“I was hacking into their platform and stealing their customer database so I could use their customer logins to access their [consumer] databases,” Ngo said. “I was in their systems for almost a year without them knowing.”

Very soon after gaining access to MicroBilt, Ngo says, he stood up Superget[.]info, a website that advertised the sale of individual consumer records. Ngo said initially his service was quite manual, requiring customers to request specific states or consumers they wanted information on, and he would conduct the lookups by hand.

”

I was trying to get more records at once, but the speed of our Internet in Vietnam then was very slow,” Ngo recalled. “I couldn’t download it because the database was so huge. So I just manually search for whoever need identities.”

But Ngo would soon work out how to use more powerful servers in the United States to automate the collection of larger amounts of consumer data from MicroBilt’s systems, and from other data brokers. As I wrote of Ngo’s service back in November 2011:

“Superget lets users search for specific individuals by name, city, and state. Each “credit” costs USD$1, and a successful hit on a Social Security number or date of birth costs 3 credits each. The more credits you buy, the cheaper the searches are per credit: Six credits cost $4.99; 35 credits cost $20.99, and $100.99 buys you 230 credits. Customers with special needs can avail themselves of the “reseller plan,” which promises 1,500 credits for $500.99, and 3,500 credits for $1000.99.

“Our Databases are updated EVERY DAY,” the site’s owner enthuses. “About 99% nearly 100% US people could be found, more than any sites on the internet now.”

Ngo’s intrusion into MicroBilt eventually was detected, and the company kicked him out of their systems. But he says he got back in using another vulnerability.

“I was hacking them and it was back and forth for months,” Ngo said. “They would discover [my accounts] and fix it, and I would discover a new vulnerability and hack them again.”

COURT (AD)VENTURES, AND EXPERIAN

This game of cat and mouse continued until Ngo found a much more reliable and stable source of consumer data: A U.S. based company called Court Ventures, which aggregated public records from court documents. Ngo wasn’t interested in the data collected by Court Ventures, but rather in its data sharing agreement with a third-party data broker called U.S. Info Search, which had access to far more sensitive consumer records.

Using forged documents and more than a few lies, Ngo was able to convince Court Ventures that he was a private investigator based in the United States.

“At first [when] I sign up they asked for some documents to verify,” Ngo said. “So I just used some skill about social engineering and went through the security check.”

Then, in March 2012, something even more remarkable happened: Court Ventures was purchased by Experian, one of the big three major consumer credit bureaus in the United States. And for nine months after the acquisition, Ngo was able to maintain his access.

“After that, the database was under control by Experian,” he said. “I was paying Experian good money, thousands of dollars a month.”

Whether anyone at Experian ever performed due diligence on the accounts grandfathered in from Court Ventures is unclear. But it wouldn’t have taken a rocket surgeon to figure out that this particular customer was up to something fishy.

For one thing, Ngo paid the monthly invoices for his customers’ data requests using wire transfers from a multitude of banks around the world, but mostly from new accounts at financial institutions in China, Malaysia and Singapore.

O’Neill said Ngo’s identity theft website generated tens of thousands of queries each month. For example, the first invoice Court Ventures sent Ngo in December 2010 was for 60,000 queries. By the time Experian acquired the company, Ngo’s service had attracted more than 1,400 regular customers, and was averaging 160,000 monthly queries.

More importantly, Ngo’s profit margins were enormous.

“His service was quite the racket,” he said. “Court Ventures charged him 14 cents per lookup, but he charged his customers about $1 for each query.”

By this time, O’Neill and his fellow Secret Service agents had served dozens of subpoenas tied to Ngo’s identity theft service, including one that granted them access to the email account he used to communicate with customers and administer his site. The agents discovered several emails from Ngo instructing an accomplice to pay Experian using wire transfers from different Asian banks.

TLO

Working with the Secret Service, Experian quickly zeroed in on Ngo’s accounts and shut them down. Aware of an opportunity here, the Secret Service contacted Ngo through an intermediary in the United Kingdom — a known, convicted cybercriminal who agreed to play along. The U.K.-based collaborator told Ngo he had personally shut down Ngo’s access to Experian because he had been there first and Ngo was interfering with his business.

“The U.K. guy told Ngo, ‘Hey, you’re treading on my turf, and I decided to lock you out. But as long as you’re paying a vig through me, your access won’t go away’,” O’Neill recalled.

The U.K. cybercriminal, acting at the behest of the Secret Service and U.K. authorities, told Ngo that if he wanted to maintain his access, he could agree to meet up in person. But Ngo didn’t immediately bite on the offer.

Instead, he weaseled his way into another huge data store. In much the same way he’d gained access to Court Ventures, Ngo got an account at a company called TLO, another data broker that sells access to extremely detailed and sensitive information on most Americans.

TLO’s service is accessible to law enforcement agencies and to a limited number of vetted professionals who can demonstrate they have a lawful reason to access such information. In 2014, TLO was acquired by Trans Union, one of the other three big U.S. consumer credit reporting bureaus.

And for a short time, Ngo used his access to TLO to power a new iteration of his business — an identity theft service rebranded as usearching[.]info. This site also pulled consumer data from a payday loan company that Ngo hacked into, as documented in my Sept. 2012 story, ID Theft Service Tied to Payday Loan Sites. Ngo said the hacked payday loans site gave him instant access to roughly 1,000 new fullz records each day.

BLINDED BY GREED

By this time, Ngo was a multi-millionaire: His various sites and reselling agreements with three Russian-language cybercriminal stores online had earned him more than USD $3 million. He told his parents his money came from helping companies develop websites, and even used some of his ill-gotten gains to pay off the family’s debts (its electronics business had gone belly up, and a family member had borrowed but never paid back a significant sum of money).

But mostly, Ngo said, he spent his money on frivolous things, although he says he’s never touched drugs or alcohol.

“I spent it on vacations and cars and a lot of other stupid stuff,” he said.

When TLO locked Ngo out of his account there, the Secret Service used it as another opportunity for their cybercriminal mouthpiece in the U.K. to turn the screws on Ngo yet again.

“He told Ngo he’d locked him out again, and the he could do this all day long,” O’Neill said. “And if he truly wanted lasting access to all of these places he used to have access to, he would agree to meet and form a more secure partnership.”

After several months of conversing with his apparent U.K.-based tormentor, Ngo agreed to meet him in Guam to finalize the deal. Ngo says he understood at the time that Guam is an unincorporated territory of the United States, but that he discounted the chances that this was all some kind of elaborate law enforcement sting operation.

“I was so desperate to have a stable database, and I got blinded by greed and started acting crazy without thinking,” Ngo said. “Lots of people told me ‘Don’t go!,’ but I told them I have to try and see what’s going on.”

But immediately after stepping off of the plane in Guam, he was apprehended by Secret Service agents.

“One of the names of his identity theft services was findget[.]me,” O’Neill said. “We took that seriously, and we did like he asked.”

This is Part I of a multi-part series. Check back tomorrow (Aug. 27) for Part II, which will examine what investigators learned following Ngo’s arrest, and delve into his more recent effort to right the wrongs he’s done.

The Federal Bureau of Investigation (FBI) and the Cybersecurity and Infrastructure Security Agency (CISA) on Thursday issued a joint alert to warn about the growing threat from voice phishing or “vishing” attacks targeting companies. The advisory came less than 24 hours after KrebsOnSecurity published an in-depth look at a crime group offering a service that people can hire to steal VPN credentials and other sensitive data from employees working remotely during the Coronavirus pandemic.

“The COVID-19 pandemic has resulted in a mass shift to working from home, resulting in increased use of corporate virtual private networks (VPNs) and elimination of in-person verification,” the alert reads. “In mid-July 2020, cybercriminals started a vishing campaign—gaining access to employee tools at multiple companies with indiscriminate targeting — with the end goal of monetizing the access.”

As noted in Wednesday’s story, the agencies said the phishing sites set up by the attackers tend to include hyphens, the target company’s name, and certain words — such as “support,” “ticket,” and “employee.” The perpetrators focus on social engineering new hires at the targeted company, and impersonate staff at the target company’s IT helpdesk.

The joint FBI/CISA alert (PDF) says the vishing gang also compiles dossiers on employees at the specific companies using mass scraping of public profiles on social media platforms, recruiter and marketing tools, publicly available background check services, and open-source research. From the alert:

“Actors first began using unattributed Voice over Internet Protocol (VoIP) numbers to call targeted employees on their personal cellphones, and later began incorporating spoofed numbers of other offices and employees in the victim company. The actors used social engineering techniques and, in some cases, posed as members of the victim company’s IT help desk, using their knowledge of the employee’s personally identifiable information—including name, position, duration at company, and home address—to gain the trust of the targeted employee.”

“The actors then convinced the targeted employee that a new VPN link would be sent and required their login, including any 2FA [2-factor authentication] or OTP [one-time passwords]. The actor logged the information provided by the employee and used it in real-time to gain access to corporate tools using the employee’s account.”

The alert notes that in some cases the the unsuspected employees approved the 2FA or OTP prompt, either accidentally or believing it was the result of the earlier access granted to the help desk impersonator. In other cases, the attackers were able to intercept the one-time codes by targeting the employee with SIM swapping, which involves social engineering people at mobile phone companies into to giving them control of the target’s phone number.

The agencies said crooks use the vished VPN credentials to mine the victim company databases for their customers’ personal information to leverage in other attacks.

“The actors then used the employee access to conduct further research on victims, and/or to fraudulently obtain funds using varying methods dependent on the platform being accessed,” the alert reads. “The monetizing method varied depending on the company but was highly aggressive with a tight timeline between the initial breach and the disruptive cashout scheme.”

The advisory includes a number of suggestions that companies can implement to help mitigate the threat from these vishing attacks, including:

• Restrict VPN connections to managed devices only, using mechanisms like hardware checks or installed certificates, so user input alone is not enough to access the corporate VPN.

• Restrict VPN access hours, where applicable, to mitigate access outside of allowed times.

• Employ domain monitoring to track the creation of, or changes to, corporate, brand-name domains.

• Actively scan and monitor web applications for unauthorized access, modification, and anomalous activities.

• Employ the principle of least privilege and implement software restriction policies or other controls; monitor authorized user accesses and usage.

• Consider using a formalized authentication process for employee-to-employee communications made over the public telephone network where a second factor is used to
authenticate the phone call before sensitive information can be discussed.

• Improve 2FA and OTP messaging to reduce confusion about employee authentication attempts.

• Verify web links do not have misspellings or contain the wrong domain.

• Bookmark the correct corporate VPN URL and do not visit alternative URLs on the sole basis of an inbound phone call.

• Be suspicious of unsolicited phone calls, visits, or email messages from unknown individuals claiming to be from a legitimate organization. Do not provide personal information or information about your organization, including its structure or networks, unless you are certain of a person’s authority to have the information. If possible, try to verify the caller’s identity directly with the company.

• If you receive a vishing call, document the phone number of the caller as well as the domain that the actor tried to send you to and relay this information to law enforcement.

• Limit the amount of personal information you post on social networking sites. The internet is a public resource; only post information you are comfortable with anyone seeing.

• Evaluate your settings: sites may change their options periodically, so review your security and privacy settings regularly to make sure that your choices are still appropriate.

The COVID-19 epidemic has brought a wave of email phishing attacks that try to trick work-at-home employees into giving away credentials needed to remotely access their employers’ networks. But one increasingly brazen group of crooks is taking your standard phishing attack to the next level, marketing a voice phishing service that uses a combination of one-on-one phone calls and custom phishing sites to steal VPN credentials from employees.

According to interviews with several sources, this hybrid phishing gang has a remarkably high success rate, and operates primarily through paid requests or “bounties,” where customers seeking access to specific companies or accounts can hire them to target employees working remotely at home.

And over the past six months, the criminals responsible have created dozens if not hundreds of phishing pages targeting some of the world’s biggest corporations. For now at least, they appear to be focusing primarily on companies in the financial, telecommunications and social media industries.

“For a number of reasons, this kind of attack is really effective,” said Allison Nixon, chief research officer at New York-based cyber investigations firm Unit 221B. “Because of the Coronavirus, we have all these major corporations that previously had entire warehouses full of people who are now working remotely. As a result the attack surface has just exploded.”

TARGET: NEW HIRES

A typical engagement begins with a series of phone calls to employees working remotely at a targeted organization. The phishers will explain that they’re calling from the employer’s IT department to help troubleshoot issues with the company’s virtual private networking (VPN) technology.

The goal is to convince the target either to divulge their credentials over the phone or to input them manually at a website set up by the attackers that mimics the organization’s corporate email or VPN portal.

Zack Allen is director of threat intelligence for ZeroFOX, a Baltimore-based company that helps customers detect and respond to risks found on social media and other digital channels. Allen has been working with Nixon and several dozen other researchers from various security firms to monitor the activities of this prolific phishing gang in a bid to disrupt their operations.

Allen said the attackers tend to focus on phishing new hires at targeted companies, and will often pose as new employees themselves working in the company’s IT division. To make that claim more believable, the phishers will create LinkedIn profiles and seek to connect those profiles with other employees from that same organization to support the illusion that the phony profile actually belongs to someone inside the targeted firm.

“They’ll say ‘Hey, I’m new to the company, but you can check me out on LinkedIn’ or Microsoft Teams or Slack, or whatever platform the company uses for internal communications,” Allen said. “There tends to be a lot of pretext in these conversations around the communications and work-from-home applications that companies are using. But eventually, they tell the employee they have to fix their VPN and can they please log into this website.”

SPEAR VISHING

The domains used for these pages often invoke the company’s name, followed or preceded by hyphenated terms such as “vpn,” “ticket,” “employee,” or “portal.” The phishing sites also may include working links to the organization’s other internal online resources to make the scheme seem more believable if a target starts hovering over links on the page.

Allen said a typical voice phishing or “vishing” attack by this group involves at least two perpetrators: One who is social engineering the target over the phone, and another co-conspirator who takes any credentials entered at the phishing page and quickly uses them to log in to the target company’s VPN platform in real-time.

Time is of the essence in these attacks because many companies that rely on VPNs for remote employee access also require employees to supply some type of multi-factor authentication in addition to a username and password — such as a one-time numeric code generated by a mobile app or text message. And in many cases, those codes are only good for a short duration — often measured in seconds or minutes.

But these vishers can easily sidestep that layer of protection, because their phishing pages simply request the one-time code as well.

Allen said it matters little to the attackers if the first few social engineering attempts fail. Most targeted employees are working from home or can be reached on a mobile device. If at first the attackers don’t succeed, they simply try again with a different employee.

And with each passing attempt, the phishers can glean important details from employees about the target’s operations, such as company-specific lingo used to describe its various online assets, or its corporate hierarchy.

Thus, each unsuccessful attempt actually teaches the fraudsters how to refine their social engineering approach with the next mark within the targeted organization, Nixon said.

“These guys are calling companies over and over, trying to learn how the corporation works from the inside,” she said.

NOW YOU SEE IT, NOW YOU DON’T

All of the security researchers interviewed for this story said the phishing gang is pseudonymously registering their domains at just a handful of domain registrars that accept bitcoin, and that the crooks typically create just one domain per registrar account.

“They’ll do this because that way if one domain gets burned or taken down, they won’t lose the rest of their domains,” Allen said.

More importantly, the attackers are careful to do nothing with the phishing domain until they are ready to initiate a vishing call to a potential victim. And when the attack or call is complete, they disable the website tied to the domain.

This is key because many domain registrars will only respond to external requests to take down a phishing website if the site is live at the time of the abuse complaint. This requirement can stymie efforts by companies like ZeroFOX that focus on identifying newly-registered phishing domains before they can be used for fraud.

“They’ll only boot up the website and have it respond at the time of the attack,” Allen said. “And it’s super frustrating because if you file an abuse ticket with the registrar and say, ‘Please take this domain away because we’re 100 percent confident this site is going to be used for badness,’ they won’t do that if they don’t see an active attack going on. They’ll respond that according to their policies, the domain has to be a live phishing site for them to take it down. And these bad actors know that, and they’re exploiting that policy very effectively.”

SCHOOL OF HACKS

Both Nixon and Allen said the object of these phishing attacks seems to be to gain access to as many internal company tools as possible, and to use those tools to seize control over digital assets that can quickly be turned into cash. Primarily, that includes any social media and email accounts, as well as associated financial instruments such as bank accounts and any cryptocurrencies.

Nixon said she and others in her research group believe the people behind these sophisticated vishing campaigns hail from a community of young men who have spent years learning how to social engineer employees at mobile phone companies and social media firms into giving up access to internal company tools.

Traditionally, the goal of these attacks has been gaining control over highly-prized social media accounts, which can sometimes fetch thousands of dollars when resold in the cybercrime underground. But this activity gradually has evolved toward more direct and aggressive monetization of such access.

On July 15, a number of high-profile Twitter accounts were used to tweet out a bitcoin scam that earned more than $100,000 in a few hours. According to Twitter, that attack succeeded because the perpetrators were able to social engineer several Twitter employees over the phone into giving away access to internal Twitter tools.

Nixon said it’s not clear whether any of the people involved in the Twitter compromise are associated with this vishing gang, but she noted that the group showed no signs of slacking off after federal authorities charged several people with taking part in the Twitter hack.

“A lot of people just shut their brains off when they hear the latest big hack wasn’t done by hackers in North Korea or Russia but instead some teenagers in the United States,” Nixon said. “When people hear it’s just teenagers involved, they tend to discount it. But the kinds of people responsible for these voice phishing attacks have now been doing this for several years. And unfortunately, they’ve gotten pretty advanced, and their operational security is much better now.”

PROPER ADULT MONEY-LAUNDERING

While it may seem amateurish or myopic for attackers who gain access to a Fortune 100 company’s internal systems to focus mainly on stealing bitcoin and social media accounts, that access — once established — can be re-used and re-sold to others in a variety of ways.

“These guys do intrusion work for hire, and will accept money for any purpose,” Nixon said. “This stuff can very quickly branch out to other purposes for hacking.”

For example, Allen said he suspects that once inside of a target company’s VPN, the attackers may try to add a new mobile device or phone number to the phished employee’s account as a way to generate additional one-time codes for future access by the phishers themselves or anyone else willing to pay for that access.

Nixon and Allen said the activities of this vishing gang have drawn the attention of U.S. federal authorities, who are growing concerned over indications that those responsible are starting to expand their operations to include criminal organizations overseas.

“What we see now is this group is really good on the intrusion part, and really weak on the cashout part,” Nixon said. “But they are learning how to maximize the gains from their activities. That’s going to require interactions with foreign gangs and learning how to do proper adult money laundering, and we’re already seeing signs that they’re growing up very quickly now.”

WHAT CAN COMPANIES DO?

Many companies now make security awareness and training an integral part of their operations. Some firms even periodically send test phishing messages to their employees to gauge their awareness levels, and then require employees who miss the mark to undergo additional training.

Such precautions, while important and potentially helpful, may do little to combat these phone-based phishing attacks that tend to target new employees. Both Allen and Nixon — as well as others interviewed for this story who asked not to be named — said the weakest link in most corporate VPN security setups these days is the method relied upon for multi-factor authentication.

One multi-factor option — physical security keys — appears to be immune to these sophisticated scams. The most commonly used security keys are inexpensive USB-based devices. A security key implements a form of multi-factor authentication known as Universal 2nd Factor (U2F), which allows the user to complete the login process simply by inserting the USB device and pressing a button on the device. The key works without the need for any special software drivers.

The allure of U2F devices for multi-factor authentication is that even if an employee who has enrolled a security key for authentication tries to log in at an impostor site, the company’s systems simply refuse to request the security key if the user isn’t on their employer’s legitimate website, and the login attempt fails. Thus, the second factor cannot be phished, either over the phone or Internet.

In July 2018, Google disclosed that it had not had any of its 85,000+ employees successfully phished on their work-related accounts since early 2017, when it began requiring all employees to use physical security keys in place of one-time codes.

Probably the most popular maker of security keys is Yubico, which sells a basic U2F Yubikey for $20. It offers regular USB versions as well as those made for devices that require USB-C connections, such as Apple’s newer Mac OS systems. Yubico also sells more expensive keys designed to work with mobile devices. [Full disclosure: Yubico was recently an advertiser on this site].

Nixon said many companies will likely balk at the price tag associated with equipping each employee with a physical security key. But she said as long as most employees continue to work remotely, this is probably a wise investment given the scale and aggressiveness of these voice phishing campaigns.

“The truth is some companies are in a lot of pain right now, and they’re having to put out fires while attackers are setting new fires,” she said. “Fixing this problem is not going to be simple, easy or cheap. And there are risks involved if you somehow screw up a bunch of employees accessing the VPN. But apparently these threat actors really hate Yubikey right now.”

A security flaw in the way Microsoft Windows guards users against malicious files was actively exploited in malware attacks for two years before last week, when Microsoft finally issued a software update to correct the problem.

One of the 120 security holes Microsoft fixed on Aug. 11’s Patch Tuesday was CVE-2020-1464, a problem with the way every supported version of Windows validates digital signatures for computer programs.

Code signing is the method of using a certificate-based digital signature to sign executable files and scripts in order to verify the author’s identity and ensure that the code has not been changed or corrupted since it was signed by the author.

Microsoft said an attacker could use this “spoofing vulnerability” to bypass security features intended to prevent improperly signed files from being loaded. Microsoft’s advisory makes no mention of security researchers having told the company about the flaw, which Microsoft acknowledged was actively being exploited.

In fact, CVE-2020-1464 was first spotted in attacks used in the wild back in August 2018. And several researchers informed Microsoft about the weakness over the past 18 months.

Bernardo Quintero is the manager at VirusTotal, a service owned by Google that scans any submitted files against dozens of antivirus services and displays the results. On Jan. 15, 2019, Quintero published a blog post outlining how Windows keeps the Authenticode signature valid after appending any content to the end of Windows Installer files (those ending in .MSI) signed by any software developer.

Quintero said this weakness would particularly acute if an attacker were to use it to hide a malicious Java file (.jar). And, he said, this exact attack vector was indeed detected in a malware sample sent to VirusTotal.

“In short, an attacker can append a malicious JAR to a MSI file signed by a trusted software developer (like Microsoft Corporation, Google Inc. or any other well-known developer), and the resulting file can be renamed with the .jar extension and will have a valid signature according Microsoft Windows,” Quintero wrote.

But according to Quintero, while Microsoft’s security team validated his findings, the company chose not to address the problem at the time.

“Microsoft has decided that it will not be fixing this issue in the current versions of Windows and agreed we are able to blog about this case and our findings publicly,” his blog post concluded.

Tal Be’ery, founder of Zengo, and Peleg Hadar, senior security researcher at SafeBreach Labs, penned a blog post on Sunday that pointed to a file uploaded to VirusTotal in August 2018 that abused the spoofing weakness, which has been dubbed GlueBall. The last time that August 2018 file was scanned at VirusTotal (Aug 14, 2020), it was detected as a malicious Java trojan by 28 of 59 antivirus programs.

More recently, others would likewise call attention to malware that abused the security weakness, including this post in June 2020 from the Security-in-bits blog.

Be’ery said the way Microsoft has handled the vulnerability report seems rather strange.

“It was very clear to everyone involved, Microsoft included, that GlueBall is indeed a valid vulnerability exploited in the wild,” he wrote. “Therefore, it is not clear why it was only patched now and not two years ago.”

Asked to comment on why it waited two years to patch a flaw that was actively being exploited to compromise the security of Windows computers, Microsoft dodged the question, saying Windows users who have applied the latest security updates are protected from this attack.

“A security update was released in August,” Microsoft said in a written statement sent to KrebsOnSecurity. “Customers who apply the update, or have automatic updates enabled, will be protected. We continue to encourage customers to turn on automatic updates to help ensure they are protected.”

Update, 12:45 a.m. ET: Corrected attribution on the June 2020 blog article about GlueBall exploits in the wild.