Ransomware Gangs and the Name Game Distraction

August 5, 2021
28 Comments

It’s nice when ransomware gangs have their bitcoin stolen, malware servers shut down, or are otherwise forced to disband. We hang on to these occasional victories because history tells us that most ransomware moneymaking collectives don’t go away so much as reinvent themselves under a new name, with new rules, targets and weaponry. Indeed, some of the most destructive and costly ransomware groups are now in their third incarnation.

A rough timeline of major ransomware operations and their reputed links over time.

Reinvention is a basic survival skill in the cybercrime business. Among the oldest tricks in the book is to fake one’s demise or retirement and invent a new identity. A key goal of such subterfuge is to throw investigators off the scent or to temporarily direct their attention elsewhere.

Cybercriminal syndicates also perform similar disappearing acts whenever it suits them. These organizational reboots are an opportunity for ransomware program leaders to set new ground rules for their members — such as which types of victims aren’t allowed (e.g., hospitals, governments, critical infrastructure), or how much of a ransom payment an affiliate should expect for bringing the group access to a new victim network.

I put together the above graphic to illustrate some of the more notable ransom gang reinventions over the past five years. What it doesn’t show is what we already know about the cybercriminals behind many of these seemingly disparate ransomware groups, some of whom were pioneers in the ransomware space almost a decade ago. We’ll explore that more in the latter half of this story.

One of the more intriguing and recent revamps involves DarkSide, the group that extracted a $5 million ransom from Colonial Pipeline earlier this year, only to watch much of it get clawed back in an operation by the U.S. Department of Justice.

After acknowledging someone had also seized their Internet servers, DarkSide announced it was folding. But a little more than a month later, a new ransomware affiliate program called BlackMatter emerged, and experts quickly determined BlackMatter was using the same unique encryption methods that DarkSide had used in their attacks.

DarkSide’s demise roughly coincided with that of REvil, a long-running ransomware group that claims to have extorted more than $100 million from victims. REvil’s last big victim was Kaseya, a Miami-based company whose products help system administrators manage large networks remotely. That attack let REvil deploy ransomware to as many as 1,500 organizations that used Kaseya.

REvil demanded a whopping $70 million to release a universal decryptor for all victims of the Kaseya attack. Just days later, President Biden reportedly told Russian President Vladimir Putin that he expects Russia to act when the United States shares information on specific Russians involved in ransomware activity.

A REvil ransom note.

Whether that conversation prompted actions is unclear. But REvil’s victim shaming blog would disappear from the dark web just four days later.

Mark Arena, CEO of cyber threat intelligence firm Intel 471, said it remains unclear whether BlackMatter is the REvil crew operating under a new banner, or if it is simply the reincarnation of DarkSide.

But one thing is clear, Arena said: “Likely we will see them again unless they’ve been arrested.”

Likely, indeed. REvil is widely considered a reboot of GandCrab, a prolific ransomware gang that boasted of extorting more than $2 billion over 12 months before abruptly closing up shop in June 2019. “We are living proof that you can do evil and get off scot-free,” Gandcrab bragged.

And wouldn’t you know it: Researchers have found GandCrab shared key behaviors with Cerber, an early ransomware-as-a-service operation that stopped claiming new victims at roughly the same time that GandCrab came on the scene. Continue reading →

The Life Cycle of a Breached Database

July 29, 2021
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Every time there is another data breach, we are asked to change our password at the breached entity. But the reality is that in most cases by the time the victim organization discloses an incident publicly the information has already been harvested many times over by profit-seeking cybercriminals. Here’s a closer look at what typically transpires in the weeks or months before an organization notifies its users about a breached database.

Our continued reliance on passwords for authentication has contributed to one toxic data spill or hack after another. One might even say passwords are the fossil fuels powering most IT modernization: They’re ubiquitous because they are cheap and easy to use, but that means they also come with significant trade-offs — such as polluting the Internet with weaponized data when they’re leaked or stolen en masse.

When a website’s user database gets compromised, that information invariably turns up on hacker forums. There, denizens with computer rigs that are built primarily for mining virtual currencies can set to work using those systems to crack passwords.

How successful this password cracking is depends a great deal on the length of one’s password and the type of password hashing algorithm the victim website uses to obfuscate user passwords. But a decent crypto-mining rig can quickly crack a majority of password hashes generated with MD5 (one of the weaker and more commonly-used password hashing algorithms).

“You hand that over to a person who used to mine Ethereum or Bitcoin, and if they have a large enough dictionary [of pre-computed hashes] then you can essentially break 60-70 percent of the hashed passwords in a day or two,” said Fabian Wosar, chief technology officer at security firm Emsisoft.

From there, the list of email addresses and corresponding cracked passwords will be run through various automated tools that can check how many email address and password pairs in a given leaked data set also work at other popular websites (and heaven help those who’ve re-used their email password elsewhere).

This sifting of databases for low-hanging fruit and password re-use most often yields less than a one percent success rate — and usually far less than one percent.

But even a hit rate below one percent can be a profitable haul for fraudsters, particularly when they’re password testing databases with millions of users. From there, the credentials are eventually used for fraud and resold in bulk to legally murky online services that index and resell access to breached data.

Much like WeLeakInfo and others operated before being shut down by law enforcement agencies, these services sell access to anyone who wants to search through billions of stolen credentials by email address, username, password, Internet address, and a variety of other typical database fields.

TARGETED PHISHING

So hopefully by this point it should be clear why re-using passwords is generally a bad idea. But the more insidious threat with hacked databases comes not from password re-use but from targeted phishing activity in the early days of a breach, when relatively few ne’er-do-wells have got their hands on a hot new hacked database.

Earlier this month, customers of the soccer jersey retailer classicfootballshirts.co.uk started receiving emails with a “cash back” offer. The messages addressed customers by name and referenced past order numbers and payment amounts tied to each account. The emails encouraged recipients to click a link to accept the cash back offer, and the link went to a look-alike domain that requested bank information.

The targeted phishing message that went out to classicfootballshirts.co.uk customers this month.

“It soon became clear that customer data relating to historic orders had been compromised to conduct this attack,” Classicfootballshirts said in a statement about the incident. Continue reading →

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PlugwalkJoe Does the Perp Walk

July 26, 2021
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Joseph “PlugwalkJoe” O’Connor, in a photo from a paid press release on Sept. 02, 2020, pitching him as a trustworthy cryptocurrency expert and advisor.

One day after last summer’s mass-hack of Twitter, KrebsOnSecurity wrote that 22-year-old British citizen Joseph “PlugwalkJoe” O’Connor appeared to have been involved in the incident. When the U.S. Justice Department last week announced O’Connor’s arrest and indictment, his alleged role in the Twitter compromise was well covered in the media.

But most of the coverage seems to have overlooked the far more sinister criminal charges in the indictment, which involve an underground scene wherein young men turn to extortion, sextortion, SIM swapping, death threats and physical attacks — all in a frenzied effort to seize control over social media accounts.

Skim the government’s indictment and you might overlook a footnote on Page 4 that says O’Connor is part of a group that had exactly zero reservations about using their playbook of harassment tactics against law enforcement agents who were already investigating their alleged crimes.

“O’Connor has potentially been linked to additional prior swatting incidents and possibly (although not confirmed and currently still under investigation) the swatting of a U.S. law enforcement officer,” the footnote reads.

Swatting involves making a false report to authorities in a target’s name with the intention of sending a heavily armed police force to that person’s address. It’s a potentially deadly hoax: Earlier this month, a Tennessee man was sentenced to 60 months in prison for setting in motion a swatting attack that led to the death of a 60-year-old grandfather.

As for the actual criminal charges, O’Connor faces ten counts, including conspiracy, computer intrusion, extortive communications, stalking and threatening communications.

FEMALE TARGETS

All of those come into play in the case of the Snapchat account of actor Bella Thorne, who was allegedly targeted by PlugwalkJoe and associates in June 2019.

Investigators say O’Connor was involved in a “SIM swap” against Thorne’s mobile phone number. Unauthorized SIM swapping is a scheme in which fraudsters trick or bribe employees at wireless phone companies into redirecting the target’s text messages and phone calls to a device they control. From there, the attackers can reset the password for any online account that allows password resets via SMS.

In this case, the SIM swap was done to wrest control over Thorne’s Snapchat account. Once inside, the attackers found nude photos of Thorne, which they then threatened to release unless she agreed to post on social media thanking the hackers using their online handles.

The intruders posted on Thorne’s Snapchat, “Will drop nudes if 5000 of you follow @PlugwalkJoe.” Thorne told the feds her phone lost service shortly before her account was hijacked. Investigators later found the same Internet address used to access Thorne’s Snapchat account also was used minutes later to access “@Joe” on Instagram, which O’Connor has claimed publicly.

On June 15, 2019, Thorne posted on Twitter that she’d been “threatened with my own nudes,” and posted screenshots of the text message with the individual who had extorted him/her. Thorne said she was releasing the photographs so that the individual would not be able to “take yet another thing from me.”

The indictment alleges O’Connor also swatted and cyberstalked a 16-year-old girl, sending her nude photos and threatening to rape and/or murder her and her family.

Social media personality Addison Rae had 55 million followers when her TikTok account got hacked last August. I noted on Twitter at the time that PlugWalkJoe had left his calling card yet again. The indictment alleges O’Connor also was involved in a SIM-swap against Rae’s mobile number.


Continue reading →

Serial Swatter Who Caused Death Gets Five Years in Prison

July 21, 2021
69 Comments

A 18-year-old Tennessee man who helped set in motion a fraudulent distress call to police that led to the death of a 60-year-old grandfather in 2020 was sentenced to 60 months in prison today.

60-year-old Mark Herring died of a heart attack after police surrounded his home in response to a swatting attack.

Shane Sonderman, of Lauderdale County, Tenn. admitted to conspiring with a group of criminals that’s been “swatting” and harassing people for months in a bid to coerce targets into giving up their valuable Twitter and Instagram usernames.

At Sonderman’s sentencing hearing today, prosecutors told the court the defendant and his co-conspirators would text and call targets and their families, posting their personal information online and sending them pizzas and other deliveries of food as a harassment technique.

Other victims of the group told prosecutors their tormentors further harassed them by making false reports of child abuse to social services local to the target’s area, and false reports in the target’s name to local suicide prevention hotlines.

Eventually, when subjects of their harassment refused to sell or give up their Twitter and Instagram usernames, Sonderman and others would swat their targets — or make a false report to authorities in the target’s name with the intention of sending a heavily armed police response to that person’s address.

For weeks throughout March and April 2020, 60-year-old Mark Herring of Bethpage, Tenn. was inundated with text messages asking him to give up his @Tennessee Twitter handle. When he ignored the requests, Sonderman and his buddies began having food delivered to Herring’s home via cash on delivery.

At one point, Sonderman posted Herring’s home address in a Discord chat room used by the group, and a minor in the United Kingdom quickly followed up by directing a swatting attack on Herring’s home.

Ann Billings was dating Mr. Herring and was present when the police surrounded his home. She recalled for the Tennessee court today how her friend died shortly thereafter of a heart attack.

Billings said she first learned of the swatting when a neighbor called and asked why the street was lined with police cars. When Mr. Herring stepped out on the back porch to investigate, police told him to put his hands up and to come to the street.

Unable to disengage a lock on his back fence, Herring was instructed to somehow climb over the fence with his hands up.

“He was starting to get more upset,” Billings recalled. “He said, ‘I’m a 60-year-old fat man and I can’t do that.'”

Billings said Mr. Herring then offered to crawl under a gap in the fence, but when he did so and stood up, he collapsed of a heart attack. Herring died at a nearby hospital soon after.

Mary Frances Herring, who was married to Mr. Herring for 28 years, said her late husband was something of a computer whiz in his early years who secured the @Tennessee Twitter handle shortly after Twitter came online. Internet archivist Jason Scott says Herring was the creator of the successful software products Sparkware and QWIKMail; Scott has 2 hours worth of interviews with Herring from 20 years ago here.

Perhaps the most poignant testimony today came when Ms. Herring said her husband — who was killed by people who wanted to steal his account — had a habit of registering new Instagram usernames as presents for friends and family members who’d just had children.

“If someone was having a baby, he would ask them, ‘What are your naming the baby?’,” Ms. Herring said. “And he would get them that Instagram name and give it to them as a gift.” Continue reading →

Spam Kingpin Peter Levashov Gets Time Served

July 20, 2021
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Peter Levashov, appearing via Zoom at his sentencing hearing today.

A federal judge in Connecticut today handed down a sentence of time served to spam kingpin Peter “Severa” Levashov, a prolific purveyor of malicious and junk email, and the creator of malware strains that infected millions of Microsoft computers globally. Levashov has been in federal custody since his extradition to the United States and guilty plea in 2018, and was facing up to 12 more years in prison. Instead, he will go free under three years of supervised release and a possible fine.

A native of St. Petersburg, Russia, the 40-year-old Levashov operated under the hacker handle “Severa.” Over the course of his 15-year cybercriminal career, Severa would emerge as a pivotal figure in the cybercrime underground, serving as the primary moderator of a spam community that spanned multiple top Russian cybercrime forums.

Severa created and then leased out to others some of the nastiest cybercrime engines in history — including the Storm worm, and the Waledac and Kelihos spam botnets. His central role in the spam forums gave Severa a prime spot to advertise the services tied to his various botnets, while allowing him to keep tabs on the activities of other spammers.

Severa rented out segments of his Waledac botnet to anyone seeking a vehicle for sending spam. For $200, vetted users could hire his botnet to blast one million emails containing malware or ads for male enhancement drugs. Junk email campaigns touting employment or “money mule” scams cost $300 per million, and phishing emails could be blasted out through Severa’s botnet for the bargain price of $500 per million.

Severa was a moderator on the Russian spam community Spamdot[.]biz. In this paid ad from 2004, Severa lists prices to rent his spam botnet.

Early in his career, Severa worked very closely with two major purveyors of spam. One was Alan Ralsky, an American spammer who was convicted in 2009 of paying Severa and other spammers to promote pump-and-dump stock scams.

The other was a major spammer who went by the nickname “Cosma,” the cybercriminal thought to be responsible for managing the Rustock botnet (so named because it was a Russian botnet frequently used to send pump-and-dump stock spam). Microsoft, which has battled to scrub botnets like Rustock off of millions of PCs, later offered a still-unclaimed $250,000 reward for information leading to the arrest and conviction of the Rustock author.

Severa ran several affiliate programs that paid cybercriminals to trick people into installing fake antivirus software. In 2011, KrebsOnSecurity dissected “SevAntivir” — Severa’s eponymous fake antivirus affiliate program  — showing it was used to deploy new copies of the Kelihos spam botnet.

A screenshot of the “SevAntivir” fake antivirus or “scareware” affiliate program run by Severa.

In 2010, Microsoft — in tandem with a number of security researchers — launched a combined technical and legal sneak attack on the Waledac botnet, successfully dismantling it. The company would later do the same to the Kelihos botnet, a global spam machine which shared a great deal of code with Waledac and infected more than 110,000 Microsoft Windows PCs.

Levashov was arrested in 2017 while in Barcelona, Spain with his family. According to a lengthy April 2017 story in Wired.com, he got caught because he violated a basic security no-no: He used the same log-in credentials to both run his criminal enterprise and log into sites like iTunes.

In fighting his extradition to the United States, Levashov famously told the media, “If I go to the U.S., I will die in a year.” But a few months after his extradition, Levashov would plead guilty to four felony counts, including intentional damage to protected computers, conspiracy, wire fraud and aggravated identity theft.

At his sentencing hearing today, Levashov thanked his wife, attorney and the large number of people who wrote the court in support of his character, but otherwise declined to make a statement. His attorney read a lengthy statement explaining that Levashov got into spamming as a way to provide for his family, and that over a period of many years that business saw him supporting countless cybercrime operations. Continue reading →

Don’t Wanna Pay Ransom Gangs? Test Your Backups.

July 19, 2021
71 Comments

Browse the comments on virtually any story about a ransomware attack and you will almost surely encounter the view that the victim organization could have avoided paying their extortionists if only they’d had proper data backups. But the ugly truth is there are many non-obvious reasons why victims end up paying even when they have done nearly everything right from a data backup perspective.

This story isn’t about what organizations do in response to cybercriminals holding their data for hostage, which has become something of a best practice among most of the top ransomware crime groups today. Rather, it’s about why victims still pay for a key needed to decrypt their systems even when they have the means to restore everything from backups on their own.

Experts say the biggest reason ransomware targets and/or their insurance providers still pay when they already have reliable backups is that nobody at the victim organization bothered to test in advance how long this data restoration process might take.

“In a lot of cases, companies do have backups, but they never actually tried to restore their network from backups before, so they have no idea how long it’s going to take,” said Fabian Wosar, chief technology officer at Emsisoft. “Suddenly the victim notices they have a couple of petabytes of data to restore over the Internet, and they realize that even with their fast connections it’s going to take three months to download all these backup files. A lot of IT teams never actually make even a back-of-the-napkin calculation of how long it would take them to restore from a data rate perspective.”

Wosar said the next most-common scenario involves victims that have off-site, encrypted backups of their data but discover that the digital key needed to decrypt their backups was stored on the same local file-sharing network that got encrypted by the ransomware.

The third most-common impediment to victim organizations being able to rely on their backups is that the ransomware purveyors manage to corrupt the backups as well.

“That is still somewhat rare,” Wosar said. “It does happen but it’s more the exception than the rule. Unfortunately, it is still quite common to end up having backups in some form and one of these three reasons prevents them from being useful.” Continue reading →

Microsoft Patch Tuesday, July 2021 Edition

July 13, 2021
49 Comments

Microsoft today released updates to patch at least 116 security holes in its Windows operating systems and related software. At least four of the vulnerabilities addressed today are under active attack, according to Microsoft.

Thirteen of the security bugs quashed in this month’s release earned Microsoft’s most-dire “critical” rating, meaning they can be exploited by malware or miscreants to seize remote control over a vulnerable system without any help from users.

Another 103 of the security holes patched this month were flagged as “important,” which Microsoft assigns to vulnerabilities “whose exploitation could result in compromise of the confidentiality, integrity, or availability of user data, or of the integrity or availability of processing resources.”

Among the critical bugs is of course the official fix for the PrintNightmare print spooler flaw in most versions of Windows (CVE-2021-34527) that prompted Microsoft to rush out a patch for a week ago in response to exploit code for the flaw that got accidentally published online. That patch seems to have caused a number of problems for Windows users. Here’s hoping the updated fix resolves some of those issues for readers who’ve been holding out.

CVE-2021-34448 is a critical remote code execution vulnerability in the scripting engine built into every supported version of Windows — including server versions. Microsoft says this flaw is being exploited in the wild.

Both CVE-2021-33771 and CVE-2021-31979 are elevation of privilege flaws in the Windows kernel. Both are seeing active exploitation, according to Microsoft. Continue reading →

Spike in “Chain Gang” Destructive Attacks on ATMs

July 9, 2021
47 Comments

Last summer, financial institutions throughout Texas started reporting a sudden increase in attacks involving well-orchestrated teams that would show up at night, use stolen trucks and heavy chains to rip Automated Teller Machines (ATMs) out of their foundations, and make off with the cash boxes inside. Now it appears the crime — known variously as “ATM smash-and-grab” or “chain gang” attacks — is rapidly increasing in other states.

Four different ATM “chain gang” attacks in Texas recently. Image: Texas Bankers Association.

The Texas Bankers Association documented at least 139 chain gang attacks against Texas financial institutions in the year ending November 2020. The association says organized crime is the main source of the destructive activity, and that Houston-based FBI officials have made more than 50 arrests and are actively tracking about 250 individuals suspected of being part of these criminal rings.

From surveillance camera footage examined by fraud investigators, the perpetrators have followed the same playbook in each incident. The bad guys show up in the early morning hours with a truck or tractor that’s been stolen from a local construction site.

Then two or three masked men will pry the front covering from the ATM using crowbars, and attach heavy chains to the cash machine. The canisters of cash inside are exposed once the crooks pull the ATM’s safe door off using the stolen vehicle.

In nearly all cases, the perpetrators are done in less than five minutes.

Tracey Santor is the bond product manager for Travelers, which insures a large number of financial institutions against this type of crime. Santor said investigators questioning some of the suspects learned that the smash-and-grabs are used as a kind of initiation for would-be gang members.

“One of the things they found out during the arrest was the people wanting to be in the gang were told they had to bring them $250,000 within a week,” Santor said. “And they were given instructions on how to do it. I’ve also heard of cases where the perpetrators put construction cones around the ATM so it looks to anyone passing by that they’re legitimately doing construction at the site.”

Santor said the chain gang attacks have spread to other states, and that in the year ending June 2021 Travelers saw a 257 percent increase in the number of insurance claims related to ATM smash-and-grabs.

That 257 percent increase also includes claims involving incidents where attackers will crash a stolen car into a convenience store, and then in the ensuing commotion load the store’s ATM into the back of the vehicle and drive away.

In addition to any cash losses — which can often exceed $200,000 — replacing destroyed ATMs and any associated housing can take weeks, and newer model ATMs can cost $80,000 or more.

“It’s not stopping,” Santor said of the chain gang attacks. “In the last year we counted 32 separate states we’ve seen this type of attack in. Normally we are seeing single digits across the country. 2021 is going to be the same or worse for us than last year.” Continue reading →

Kaseya Left Customer Portal Vulnerable to 2015 Flaw in its Own Software

July 8, 2021
37 Comments

Last week cybercriminals deployed ransomware to 1,500 organizations, including many that provide IT security and technical support to other companies. The attackers exploited a vulnerability in software from Kaseya, a Miami-based company whose products help system administrators manage large networks remotely. Now it appears Kaseya’s customer service portal was left vulnerable until last week to a data-leaking security flaw that was first identified in the same software six years ago.

On July 3, the REvil ransomware affiliate program began using a zero-day security hole (CVE-2021-30116) to deploy ransomware to hundreds of IT management companies running Kaseya’s remote management software — known as the Kaseya Virtual System Administrator (VSA).

According to this entry for CVE-2021-30116, the security flaw that powers that Kaseya VSA zero-day was assigned a vulnerability number on April 2, 2021, indicating Kaseya had roughly three months to address the bug before it was exploited in the wild.

Also on July 3, security incident response firm Mandiant notified Kaseya that their billing and customer support site —portal.kaseya.net — was vulnerable to CVE-2015-2862, a “directory traversal” vulnerability in Kaseya VSA that allows remote users to read any files on the server using nothing more than a Web browser.

As its name suggests, CVE-2015-2862 was issued in July 2015. Six years later, Kaseya’s customer portal was still exposed to the data-leaking weakness.

The Kaseya customer support and billing portal. Image: Archive.org.

Mandiant notified Kaseya after hearing about it from Alex Holden, founder and chief technology officer of Milwaukee-based cyber intelligence firm Hold Security. Holden said the 2015 vulnerability was present on Kaseya’s customer portal until Saturday afternoon, allowing him to download the site’s “web.config” file, a server component that often contains sensitive information such as usernames and passwords and the locations of key databases.

“It’s not like they forgot to patch something that Microsoft fixed years ago,” Holden said. “It’s a patch for their own software. And it’s not zero-day. It’s from 2015!”

The official description of CVE-2015-2862 says a would-be attacker would need to be already authenticated to the server for the exploit to work. But Holden said that was not the case with the vulnerability on the Kaseya portal that he reported via Mandiant.

“This is worse because the CVE calls for an authenticated user,” Holden said. “This was not.”

Michael Sanders, executive vice president of account management at Kaseya, confirmed that the customer portal was taken offline in response to a vulnerability report. Sanders said the portal had been retired in 2018 in favor of a more modern customer support and ticketing system, yet somehow the old site was still left available online.

“It was deprecated but left up,” Sanders said.

In a written statement shared with KrebsOnSecurity, Kaseya said that in 2015 CERT reported two vulnerabilities in its VSA product.

“We worked with CERT on responsible disclosure and released patches for VSA versions V7, R8, R9 and R9 along with the public disclosure (CVEs) and notifications to our customers. Portal.kaseya.net was not considered by our team to be part of the VSA shipping product and was not part of the VSA product patch in 2015. It has no access to customer endpoints and has been shut down – and will no longer be enabled or used by Kaseya.”

“At this time, there is no evidence this portal was involved in the VSA product security incident,” the statement continued. “We are continuing to do forensic analysis on the system and investigating what data is actually there.” Continue reading →

Microsoft Issues Emergency Patch for Windows Flaw

July 7, 2021
91 Comments

Microsoft on Tuesday issued an emergency software update to quash a security bug that’s been dubbed “PrintNightmare,” a critical vulnerability in all supported versions of Windows that is actively being exploited. The fix comes a week ahead of Microsoft’s normal monthly Patch Tuesday release, and follows the publishing of exploit code showing would-be attackers how to leverage the flaw to break into Windows computers.

At issue is CVE-2021-34527, which involves a flaw in the Windows Print Spooler service that could be exploited by attackers to run code of their choice on a target’s system. Microsoft says it has already detected active exploitation of the vulnerability.

Satnam Narang, staff research engineer at Tenable, said Microsoft’s patch warrants urgent attention because of the vulnerability’s ubiquity across organizations and the prospect that attackers could exploit this flaw in order to take over a Windows domain controller.

“We expect it will only be a matter of time before it is more broadly incorporated into attacker toolkits,” Narang said. “PrintNightmare will remain a valuable exploit for cybercriminals as long as there are unpatched systems out there, and as we know, unpatched vulnerabilities have a long shelf life for attackers.”

In a blog post, Microsoft’s Security Response Center said it was delayed in developing fixes for the vulnerability in Windows Server 2016, Windows 10 version 1607, and Windows Server 2012. The fix also apparently includes a new feature that allows Windows administrators to implement stronger restrictions on the installation of printer software.

“Prior to installing the July 6, 2021, and newer Windows Updates containing protections for CVE-2021-34527, the printer operators’ security group could install both signed and unsigned printer drivers on a printer server,” reads Microsoft’s support advisory. “After installing such updates, delegated admin groups like printer operators can only install signed printer drivers. Administrator credentials will be required to install unsigned printer drivers on a printer server going forward.”

Windows 10 users can check for the patch by opening Windows Update. Chances are, it will show what’s pictured in the screenshot below — that KB5004945 is available for download and install. A reboot will be required after installation.

Friendly reminder: It’s always a good idea to backup your data before applying security updates. Windows 10 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.

Microsoft’s out-of-band update may not completely fix the PrinterNightmare vulnerability. Security researcher Benjamin Delpy posted on Twitter that the exploit still works on a fully patched Windows server if the server also has Point & Print enabled — a Windows feature that automatically downloads and installs available printer drivers.

Delpy said it’s common for organizations to enable Point & Print using group policies because it allows users to install printer updates without getting approval first from IT.

This post will be updated if Windows users start reporting any issues in applying the patch.