Many online services allow users to reset their passwords by clicking a link sent via SMS, and this unfortunately widespread practice has turned mobile phone numbers into de facto identity documents. Which means losing control over one thanks to a divorce, job termination or financial crisis can be devastating.

Even so, plenty of people willingly abandon a mobile number without considering the potential fallout to their digital identities when those digits invariably get reassigned to someone else. New research shows how fraudsters can abuse wireless provider websites to identify available, recycled mobile numbers that allow password resets at a range of email providers and financial services online.

Researchers in the computer science department at Princeton University say they sampled 259 phone numbers at two major wireless carriers, and found 171 of them were tied to existing accounts at popular websites, potentially allowing those accounts to be hijacked.

The Princeton team further found 100 of those 259 numbers were linked to leaked login credentials on the web, which could enable account hijackings that defeat SMS-based multi-factor authentication.

“Our key finding is that attackers can feasibly leverage number recycling to target previous owners and their accounts,” the researchers wrote. “The moderate to high hit rates of our testing methods indicate that most recycled numbers are vulnerable to these attacks. Furthermore, by focusing on blocks of Likely recycled numbers, an attacker can easily discover available recycled numbers, each of which then becomes a potential target.”

The researchers located newly-recycled mobile numbers by browsing numbers made available to customers interested in signing up for a prepaid account at T-Mobile or Verizon (apparently AT&T doesn’t provide a similar interface). They said they were able to identify and ignore large blocks of new, unused numbers, as these blocks tend to be made available consecutively — much like newly printed money is consecutively numbered in stacks.

The Princeton team has a number of recommendations for T-Mobile and Verizon, noting that both carriers allow unlimited inquiries on their prepaid customer platforms online — meaning there is nothing to stop attackers from automating this type of number reconnaissance.

“On postpaid interfaces, Verizon already has safeguards and T-Mobile does not even support changing numbers online,” the researchers wrote. “However, the number pool is shared between postpaid and prepaid, rendering all subscribers vulnerable to attacks.”

They also recommend the carriers teach their support employees to remind customers about the risks of relinquishing a mobile number without first disconnecting it from other identities and sites online, advice they generally did not find was offered when interacting with customer support regarding number changes.

In addition, the carriers could offer their own “number parking” service for customers who know they will not require phone service for an extended period of time, or for those who just aren’t sure what they want to do with a number. Such services are already offered by companies like NumberBarn and Park My Phone, and they generally cost between $2-5 per month.

The Princeton study recommends consumers who are considering a number change instead either store the digits at an existing number parking service, or “port” the number to something like Google Voice. For a one-time $20 fee, Google Voice will let you port the number, and then you can continue to receive texts and calls to that number via Google Voice, or you can forward them to another number.

Porting seems like less of a hassle and potentially safer considering the average user has something like 150 accounts online, and a significant number of those accounts are going to be tied to one’s mobile number.

The full Princeton study is available here (PDF).

In a Twitter discussion last week on ransomware attacks, KrebsOnSecurity noted that virtually all ransomware strains have a built-in failsafe designed to cover the backsides of the malware purveyors: They simply will not install on a Microsoft Windows computer that already has one of many types of virtual keyboards installed — such as Russian or Ukrainian. So many readers had questions in response to the tweet that I thought it was worth a blog post exploring this one weird cyber defense trick.

The Twitter thread came up in a discussion on the ransomware attack against Colonial Pipeline, which earlier this month shut down 5,500 miles of fuel pipe for nearly a week, causing fuel station supply shortages throughout the country and driving up prices. The FBI said the attack was the work of DarkSide, a new-ish ransomware-as-a-service offering that says it targets only large corporations.

DarkSide and other Russian-language affiliate moneymaking programs have long barred their criminal associates from installing malicious software on computers in a host of Eastern European countries, including Ukraine and Russia. This prohibition dates back to the earliest days of organized cybercrime, and it is intended to minimize scrutiny and interference from local authorities.

In Russia, for example, authorities there generally will not initiate a cybercrime investigation against one of their own unless a company or individual within the country’s borders files an official complaint as a victim. Ensuring that no affiliates can produce victims in their own countries is the easiest way for these criminals to stay off the radar of domestic law enforcement agencies.

Possibly feeling the heat from being referenced in President Biden’s Executive Order on cybersecurity this past week, the DarkSide group sought to distance itself from their attack against Colonial Pipeline. In a message posted to its victim shaming blog, DarkSide tried to say it was “apolitical” and that it didn’t wish to participate in geopolitics.

“Our goal is to make money, and not creating problems for society,” the DarkSide criminals wrote last week. “From today we introduce moderation and check each company that our partners want to encrypt to avoid social consequences in the future.”

But here’s the thing: Digital extortion gangs like DarkSide take great care to make their entire platforms geopolitical, because their malware is engineered to work only in certain parts of the world.

DarkSide, like a great many other malware strains, has a hard-coded do-not-install list of countries which are the principal members of the Commonwealth of Independent States (CIS) — former Soviet satellites that all currently have favorable relations with the Kremlin, including Azerbaijan, Belarus, Georgia, Romania, Turkmenistan, Ukraine and Uzbekistan. The full exclusion list in DarkSide (published by Cybereason) is below:

Simply put, countless malware strains will check for the presence of one of these languages on the system, and if they’re detected the malware will exit and fail to install.

[Side note. Many security experts have pointed to connections between the DarkSide and REvil (a.k.a. “Sodinokibi”) ransomware groups. REvil was previously known as GandCrab, and one of the many things GandCrab had in common with REvil was that both programs barred affiliates from infecting victims in Syria. As we can see from the chart above, Syria is also exempted from infections by DarkSide ransomware. And DarkSide itself proved their connection to REvil this past week when it announced it was closing up shop after its servers and bitcoin funds were seized.]

CAVEAT EMPTOR

Will installing one of these languages keep your Windows computer safe from all malware? Absolutely not. There is plenty of malware that doesn’t care where in the world you are. And there is no substitute for adopting a defense-in-depth posture, and avoiding risky behaviors online.

But is there really a downside to taking this simple, free, prophylactic approach? None that I can see, other than perhaps a sinking feeling of capitulation. The worst that could happen is that you accidentally toggle the language settings and all your menu options are in Russian.

If this happens (and the first time it does the experience may be a bit jarring) hit the Windows key and the space bar at the same time; if you have more than one language installed you will see the ability to quickly toggle from one to the other. The little box that pops up when one hits that keyboard combo looks like this:

Cybercriminals are notoriously responsive to defenses which cut into their profitability, so why wouldn’t the bad guys just change things up start ignoring the language check? Well, they certainly can and maybe even will do that (a recent version of DarkSide analyzed by Mandiant did not perform the system language check).

But doing so increases the risk to their personal safety and fortunes by some non-trivial amount, said Allison Nixon, chief research officer at New York City-based cyber investigations firm Unit221B.

Nixon said because of Russia’s unique legal culture, criminal hackers in that country employ these checks to ensure they are only attacking victims outside of the country.

“This is for their legal protection,” Nixon said. “Installing a Cyrillic keyboard, or changing a specific registry entry to say ‘RU’, and so forth, might be enough to convince malware that you are Russian and off limits. This can technically be used as a ‘vaccine’ against Russian malware.”

Nixon said if enough people do this in large numbers, it may in the short term protect some people, but more importantly in the long term it forces Russian hackers to make a choice: Risk losing legal protections, or risk losing income.

“Essentially, Russian hackers will end up facing the same difficulty that defenders in the West must face — the fact that it is very difficult to tell the difference between a domestic machine and a foreign machine masquerading as a domestic one,” she said.

KrebsOnSecurity asked Nixon’s colleague at Unit221B — founder Lance James — what he thought about the efficacy of another anti-malware approach suggested by Twitter followers who chimed in on last week’s discussion: Adding entries to the Windows registry that specify the system is running as a virtual machine (VM). In a bid to stymie analysis by antivirus and security firms, some malware authors have traditionally configured their malware to quit installing if it detects it is running in a virtual environment.

But James said this prohibition is no longer quite so common, particularly since so many organizations have transitioned to virtual environments for everyday use.

“Being a virtual machine doesn’t stop malware like it used to,” James said. “In fact, a lot of the ransomware we’re seeing now is running on VMs.”

But James says he loves the idea of everyone adding a language from the CIS country list so much he’s produced his own clickable two-line Windows batch script that adds a Russian language reference in the specific Windows registry keys that are checked by malware. The script effectively allows one’s Windows PC to look like it has a Russian keyboard installed without actually downloading the added script libraries from Microsoft.

To install a different keyboard language on a Windows 10 computer the old fashioned way, hit the Windows key and X at the same time, then select Settings, and then select “Time and Language.” Select Language, and then scroll down and you should see an option to install another character set. Pick one, and the language should be installed the next time you reboot. Again, if for some reason you need to toggle between languages, Windows+Spacebar is your friend.

The DarkSide ransomware affiliate program responsible for the six-day outage at Colonial Pipeline this week that led to fuel shortages and price spikes across the country is running for the hills. The crime gang announced it was closing up shop after its servers were seized and someone drained the cryptocurrency from an account the group uses to pay affiliates.

“Servers were seized (country not named), money of advertisers and founders was transferred to an unknown account,” reads a message from a cybercrime forum reposted to the Russian OSINT Telegram channel.

“A few hours ago, we lost access to the public part of our infrastructure,” the message continues, explaining the outage affected its victim shaming blog where stolen data is published from victims who refuse to pay a ransom. The outage also took down its payment server and those that supply its distributed denial-of-service feature, which is used to turn up the heat on victims who balk at paying.

“Also, a few hours after the withdrawal, funds from the payment server (ours and clients’) were withdrawn to an unknown address,” the DarkSide admin says.

DarkSide organizers also said they were releasing decryption tools for all of the companies that have been ransomed but which haven’t yet paid.

“After that, you will be free to communicate with them wherever you want in any way you want,” the instructions read.

The DarkSide message includes passages apparently penned by a leader of the REvil ransomware-as-a-service platform. This is interesting because security experts have posited that many of DarkSide’s core members are closely tied to the REvil gang.

The REvil representative said its program was introducing new restrictions on the kinds of organizations that affiliates could hold for ransom, and that henceforth it would be forbidden to attack those in the “social sector” (defined as healthcare and educational institutions) and organizations in the “gov-sector” (state) of any country. Affiliates also will be required to get approval before infecting victims.

The new restrictions came as some Russian cybercrime forums began distancing themselves from ransomware operations altogether. On Thursday, the administrator of the popular Russian forum XSS announced the forum would no longer allow discussion threads about ransomware moneymaking programs.

“There’s too much publicity,” the XSS administrator explained. “Ransomware has gathered a critical mass of nonsense, bullshit, hype, and fuss around it. The word ‘ransomware’ has been put on a par with a number of unpleasant phenomena, such as geopolitical tensions, extortion, and government-backed hacks. This word has become dangerous and toxic.”

In a blog post on the DarkSide closure, cyber intelligence firm Intel 471 said it believes all of these actions can be tied directly to the reaction related to the high-profile ransomware attacks covered by the media this week.

“However, a strong caveat should be applied to these developments: it’s likely that these ransomware operators are trying to retreat from the spotlight more than suddenly discovering the error of their ways,” Intel 471 wrote. “A number of the operators will most likely operate in their own closed-knit groups, resurfacing under new names and updated ransomware variants. Additionally, the operators will have to find a new way to ‘wash’ the cryptocurrency they earn from ransoms. Intel 471 has observed that BitMix, a popular cryptocurrency mixing service used by Avaddon, DarkSide and REvil has allegedly ceased operations. Several apparent customers of the service reported they were unable to access BitMix in the last week.”

Microsoft today released fixes to plug at least 55 security holes in its Windows operating systems and other software. Four of these weaknesses can be exploited by malware and malcontents to seize complete, remote control over vulnerable systems without any help from users. On deck this month are patches to quash a wormable flaw, a creepy wireless bug, and yet another reason to call for the death of Microsoft’s Internet Explorer (IE) web browser.

While May brings about half the normal volume of updates from Microsoft, there are some notable weaknesses that deserve prompt attention, particularly from enterprises. By all accounts, the most pressing priority this month is CVE-2021-31166, a Windows 10 and Windows Server flaw which allows an unauthenticated attacker to remotely execute malicious code at the operating system level. With this weakness, an attacker could compromise a host simply by sending it a specially-crafted packet of data.

“That makes this bug wormable, with even Microsoft calling that out in their write-up,” said Dustin Childs, with Trend Micro’s ZDI program. “Before you pass this aside, Windows 10 can also be configured as a web server, so it is impacted as well. Definitely put this on the top of your test-and-deploy list.”

Kevin Breen from Immersive Labs said the fact that this one is just 0.2 points away from a perfect 10 CVSS score should be enough to identify just how important it is to patch.

“For ransomware operators, this kind of vulnerability is a prime target for exploitation,” Breen said. “Wormable exploits should always be a high priority, especially if they are for services that are designed to be public facing. As this specific exploit would not require any form of authentication, it’s even more appealing for attackers, and any organization using HTTP.sys protocol stack should prioritize this patch.”

Breen also called attention to CVE-2021-26419 — a vulnerability in Internet Explorer 11 — to make the case for why IE needs to stand for “Internet Exploder.” To trigger this vulnerability, a user would have to visit a site that is controlled by the attacker, although Microsoft also recognizes that it could be triggered by embedding ActiveX controls in Office Documents.

“IE needs to die – and I’m not the only one that thinks so,” Breen said. “If you are an organization that has to provide IE11 to support legacy applications, consider enforcing a policy on the users that restricts the domains that can be accessed by IE11 to only those legacy applications. All other web browsing should be performed with a supported browser.”

Another curious bug fixed this month is CVE-2020-24587, described as a “Windows Wireless Networking Information Disclosure Vulnerability.” ZDI’s Childs said this one has the potential to be pretty damaging.

“This patch fixes a vulnerability that could allow an attacker to disclose the contents of encrypted wireless packets on an affected system,” he said. “It’s not clear what the range on such an attack would be, but you should assume some proximity is needed. You’ll also note this CVE is from 2020, which could indicate Microsoft has been working on this fix for some time.”

Microsoft also patched four more security holes its Exchange Server corporate email platform, which recently was besieged by attacks on four other zero-day Exchange flaws that resulted in hundreds of thousands of servers worldwide getting hacked. One of the bugs is credited to Orange Tsai of the DEVCORE research team, who was responsible for disclosing the ProxyLogon Exchange Server vulnerability that was patched in an out-of-band release back in March.

“While none of these flaws are deemed critical in nature, it is a reminder that researchers and attackers are still looking closely at Exchange Server for additional vulnerabilities, so organizations that have yet to update their systems should do so as soon as possible,” said Satnam Narang, staff research engineer at Tenable.

As always, it’s a good idea for Windows users to get in the habit of updating at least once a month, but for regular users (read: not enterprises) it’s usually safe to wait a few days until after the patches are released, so that Microsoft has time to iron out any kinks in the new armor.

But before you update, please make sure you have backed up your system and/or important files. It’s not uncommon for a Windows update package to hose one’s system or prevent it from booting properly, and some updates have been known to erase or corrupt files.

So do yourself a favor and backup before installing any patches. Windows 10 even has some built-in tools to help you do that, either on a per-file/folder basis or by making a complete and bootable copy of your hard drive all at once.

And if you wish to ensure Windows has been set to pause updating so you can back up your files and/or system before the operating system decides to reboot and install patches on its own schedule, see this guide.

If you experience glitches or problems installing any of these patches this month, please consider leaving a comment about it below; there’s a better-than-even chance other readers have experienced the same and may chime in here with some helpful tips.

The FBI confirmed this week that a relatively new ransomware group known as DarkSide is responsible for an attack that caused Colonial Pipeline to shut down 5,550 miles of pipe, stranding countless barrels of gasoline, diesel and jet fuel on the Gulf Coast. Here’s a closer look at the DarkSide cybercrime gang, as seen through their negotiations with a recent U.S. victim that earns $15 billion in annual revenue.

New York City-based cyber intelligence firm Flashpoint said its analysts assess with a moderate-strong degree of confidence that the attack was not intended to damage national infrastructure and was simply associated with a target which had the finances to support a large payment.

“This would be consistent with DarkSide’s earlier activities, which included several ‘big game hunting’ attacks, whereby attackers target an organization that likely possesses the financial means to pay the ransom demanded by the attackers,” Flashpoint observed.

In response to public attention to the Colonial Pipeline attack, the DarkSide group sought to play down fears about widespread infrastructure attacks going forward.

“We are apolitical, we do not participate in geopolitics, do not need to tie us with a defined government and look for other our motives [sic],” reads an update to the DarkSide Leaks blog. “Our goal is to make money, and not creating problems for society. From today we introduce moderation and check each company that our partners want to encrypt to avoid social consequences in the future.”

First surfacing on Russian language hacking forums in August 2020, DarkSide is a ransomware-as-a-service platform that vetted cybercriminals can use to infect companies with ransomware and carry out negotiations and payments with victims. DarkSide says it targets only big companies, and forbids affiliates from dropping ransomware on organizations in several industries, including healthcare, funeral services, education, public sector and non-profits.

Like other ransomware platforms, DarkSide adheres to the current badguy best practice of double extortion, which involves demanding separate sums for both a digital key needed to unlock any files and servers, and a separate ransom in exchange for promise to destroy any data stolen from the victim.

At its launch, DarkSide sought to woo affiliates from competing ransomware programs by advertising a victim data leak site that gets “stable visits and media coverage,” as well as the ability to publish victim data by stages. Under the “Why choose us?” heading of the ransomware program thread, the admin answers:

“High trust level of our targets. They pay us and know that they’re going to receive decryption tools. They also know that we download data. A lot of data. That’s why the percent of our victims who pay the ransom is so high and it takes so little time to negotiate.”

In late March, DarkSide introduced a “call service” innovation that was integrated into the affiliate’s management panel, which enabled the affiliates to arrange calls pressuring victims into paying ransoms directly from the management panel.

In mid-April the ransomware program announced new capability for affiliates to launch distributed denial-of-service (DDoS) attacks against targets whenever added pressure is needed during ransom negotiations.

DarkSide also has advertised a willingness to sell information about upcoming victims before their stolen information is published on the DarkSide victim shaming blog, so that enterprising investment scammers can short the company’s stock in advance of the news.

“Now our team and partners encrypt many companies that are trading on NASDAQ and other stock exchanges,” DarkSide explains. “If the company refuses to pay, we are ready to provide information before the publication, so that it would be possible to earn in the reduction price of shares. Write to us in ‘Contact Us’ and we will provide you with detailed information.”

DarkSide also started recruiting new affiliates again last month — mainly seeking network penetration testers who can help turn a single compromised computer into a full-on data breach and ransomware incident.

“We have grown significantly in terms of the client base and in comparison to other projects (judging by the analysis of publicly available information), so we are ready to grow our team and a number of our affiliates in two fields,” DarkSide explained. The advertisement continued:

“Network penetration testing. We’re looking for one person or a team. We’ll adapt you to the work environment and provide work. High profit cuts, ability to target networks that you can’t handle on your own. New experience and stable income. When you use our product and the ransom is paid, we guarantee fair distribution of the funds. A panel for monitoring results for your target. We only accept networks where you intend to run our payload.”

DarkSide has shown itself to be fairly ruthless with victim companies that have deep pockets, but they can be reasoned with. Cybersecurity intelligence firm Intel 471 observed a negotiation between the DarkSide crew and a $15 billion U.S. victim company that was hit with a $30 million ransom demand in January 2021, and in this incident the victim’s efforts at negotiating a lower payment ultimately reduce the ransom demand by almost two-thirds.

The first exchange between DarkSide and the victim involved the usual back-and-forth establishing of trust, wherein the victim asks for assurances that stolen data will be deleted after payment.

When the victim counter-offered to pay just $2.25 million, DarkSide responded with a lengthy, derisive reply, ultimately agreeing to lower the ransom demand to $28.7 million.

“The timer it [sic] ticking and in in next 8 hours your price tag will go up to $60 million,” the crooks replied. “So, you this are your options first take our generous offer and pay to us $28,750 million US or invest some monies in quantum computing to expedite a decryption process.”

The victim complains that negotiations haven’t moved the price much, but DarkSide countered that the company can easily afford the payout. “I don’t think so,” they wrote. “You aren’t poor and aren’t children if you f*cked up you have to meet the consequences.”

The victim firm replies a day later saying they’ve gotten authority to pay $4.75 million, and their tormentors agree to lower the demand significantly to $12 million.

The victim replies that this is still a huge amount, and it tries to secure additional assurances from the ransomware group if it agrees to pay the $12 million, such as an agreement not to target the company ever again, or give anyone access to its stolen data. The victim also tried to get the attackers to hand over a decryption key before paying the full ransom demand.

The crime gang responded that its own rules prohibit it from giving away a decryption key before full payment is made, but they agree to the rest of the terms.

The victim firm agrees to pay an $11 million ransom, and their extortionists concur and promise not to attack or help anyone else attack the company’s network going forward.

Flashpoint assesses that at least some of the criminals behind DarkSide hail from another ransomware outfit called “REvil,” a.k.a. “Sodinokibi” (although Flashpoint rates this finding at only “moderate” confidence). REvil is widely considered to be the newer name for GandCrab, a ransomware-as-a-service offering that closed up shop in 2019 after bragging that it had extorted more than $2 billion.

Experts say ransomware attacks will continue to grow in sophistication, frequency and cost unless something is done to disrupt the ability of crooks to get paid for such crimes. According to a report late last year from Coveware, the average ransomware payment in the third quarter of 2020 was $233,817, up 31 percent from the second quarter of last year. Security firm Emsisoft found that almost 2,400 U.S.-based governments, healthcare facilities and schools were victims of ransomware in 2020.

Last month, a group of tech industry heavyweights lent their imprimatur to a task force that delivered an 81-page report to the Biden administration on ways to stymie the ransomware industry. Among many other recommendations, the report urged the White House to make finding, frustrating and apprehending ransomware crooks a priority within the U.S. intelligence community, and to designate the current scourge of digital extortion as a national security threat.