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Patch Tuesday, April 2026 Edition
Microsoft today pushed software updates to fix a staggering 167 security vulnerabilities in its Windows operating systems and related software, including a SharePoint Server zero-day and a publicly disclosed weakness in Windows Defender dubbed “BlueHammer.” Separately, Google Chrome fixed its fourth zero-day of 2026, and an emergency update for Adobe Reader nixes an actively exploited flaw that can lead to remote code execution.

Redmond warns that attackers are already targeting CVE-2026-32201, a vulnerability in Microsoft SharePoint Server that allows attackers to spoof trusted content or interfaces over a network.
Mike Walters, president and co-founder of Action1, said CVE-2026-32201 can be used to deceive employees, partners, or customers by presenting falsified information within trusted SharePoint environments.
“This CVE can enable phishing attacks, unauthorized data manipulation, or social engineering campaigns that lead to further compromise,” Walters said. “The presence of active exploitation significantly increases organizational risk.”
Microsoft also addressed BlueHammer (CVE-2026-33825), a privilege escalation bug in Windows Defender. According to BleepingComputer, the researcher who discovered the flaw published exploit code for it after notifying Microsoft and growing exasperated with their response. Will Dormann, senior principal vulnerability analyst at Tharros, says he confirmed that the public BlueHammer exploit code no longer works after installing today’s patches.
Satnam Narang, senior staff research engineer at Tenable, said April marks the second-biggest Patch Tuesday ever for Microsoft. Narang also said there are indications that a zero-day flaw Adobe patched in an emergency update on April 11 — CVE-2026-34621 — has seen active exploitation since at least November 2025.
Adam Barnett, lead software engineer at Rapid7, called the patch total from Microsoft today “a new record in that category” because it includes nearly 60 browser vulnerabilities. Barnett said it might be tempting to imagine that this sudden spike was tied to the buzz around the announcement a week ago today of Project Glasswing — a much-hyped but still unreleased new AI capability from Anthropic that is reportedly quite good at finding bugs in a vast array of software.
But he notes that Microsoft Edge is based on the Chromium engine, and the Chromium maintainers acknowledge a wide range of researchers for the vulnerabilities which Microsoft republished last Friday.
“A safe conclusion is that this increase in volume is driven by ever-expanding AI capabilities,” Barnett said. “We should expect to see further increases in vulnerability reporting volume as the impact of AI models extend further, both in terms of capability and availability.”
Finally, no matter what browser you use to surf the web, it’s important to completely close out and restart the browser periodically. This is really easy to put off (especially if you have a bajillion tabs open at any time) but it’s the only way to ensure that any available updates get installed. For example, a Google Chrome update released earlier this month fixed 21 security holes, including the high-severity zero-day flaw CVE-2026-5281.
For a clickable, per-patch breakdown, check out the SANS Internet Storm Center Patch Tuesday roundup. Running into problems applying any of these updates? Leave a note about it in the comments below and there’s a decent chance someone here will pipe in with a solution.
Alerte OFII : l’Office écrit aux internautes français impliqués par le piratage de leurs données
Alerte OFII : l’Office écrit aux internautes français impliqués par le piratage de leurs données
Lapsus$ relance sa vitrine de recrutement
Arnaque CySEC : le faux sauvetage après la fraude
Russia Hacked Routers to Steal Microsoft Office Tokens
Hackers linked to Russia’s military intelligence units are using known flaws in older Internet routers to mass harvest authentication tokens from Microsoft Office users, security experts warned today. The spying campaign allowed state-backed Russian hackers to quietly siphon authentication tokens from users on more than 18,000 networks without deploying any malicious software or code.
Microsoft said in a blog post today it identified more than 200 organizations and 5,000 consumer devices that were caught up in a stealthy but remarkably simple spying network built by a Russia-backed threat actor known as “Forest Blizzard.”
How targeted DNS requests were redirected at the router. Image: Black Lotus Labs.
Also known as APT28 and Fancy Bear, Forest Blizzard is attributed to the military intelligence units within Russia’s General Staff Main Intelligence Directorate (GRU). APT 28 famously compromised the Hillary Clinton campaign, the Democratic National Committee, and the Democratic Congressional Campaign Committee in 2016 in an attempt to interfere with the U.S. presidential election.
Researchers at Black Lotus Labs, a security division of the Internet backbone provider Lumen, found that at the peak of its activity in December 2025, Forest Blizzard’s surveillance dragnet ensnared more than 18,000 Internet routers that were mostly unsupported, end-of-life routers, or else far behind on security updates. A new report from Lumen says the hackers primarily targeted government agencies—including ministries of foreign affairs, law enforcement, and third-party email providers.
Black Lotus Security Engineer Ryan English said the GRU hackers did not need to install malware on the targeted routers, which were mainly older Mikrotik and TP-Link devices marketed to the Small Office/Home Office (SOHO) market. Instead, they used known vulnerabilities to modify the Domain Name System (DNS) settings of the routers to include DNS servers controlled by the hackers.
As the U.K.’s National Cyber Security Centre (NCSC) notes in a new advisory detailing how Russian cyber actors have been compromising routers, DNS is what allows individuals to reach websites by typing familiar addresses, instead of associated IP addresses. In a DNS hijacking attack, bad actors interfere with this process to covertly send users to malicious websites designed to steal login details or other sensitive information.
English said the routers attacked by Forest Blizzard were reconfigured to use DNS servers that pointed to a handful of virtual private servers controlled by the attackers. Importantly, the attackers could then propagate their malicious DNS settings to all users on the local network, and from that point forward intercept any OAuth authentication tokens transmitted by those users.
DNS hijacking through router compromise. Image: Microsoft.
Because those tokens are typically transmitted only after the user has successfully logged in and gone through multi-factor authentication, the attackers could gain direct access to victim accounts without ever having to phish each user’s credentials and/or one-time codes.
“Everyone is looking for some sophisticated malware to drop something on your mobile devices or something,” English said. “These guys didn’t use malware. They did this in an old-school, graybeard way that isn’t really sexy but it gets the job done.”
Microsoft refers to the Forest Blizzard activity as using DNS hijacking “to support post-compromise adversary-in-the-middle (AiTM) attacks on Transport Layer Security (TLS) connections against Microsoft Outlook on the web domains.” The software giant said while targeting SOHO devices isn’t a new tactic, this is the first time Microsoft has seen Forest Blizzard using “DNS hijacking at scale to support AiTM of TLS connections after exploiting edge devices.”
Black Lotus Labs engineer Danny Adamitis said it will be interesting to see how Forest Blizzard reacts to today’s flurry of attention to their espionage operation, noting that the group immediately switched up its tactics in response to a similar NCSC report (PDF) in August 2025. At the time, Forest Blizzard was using malware to control a far more targeted and smaller group of compromised routers. But Adamitis said the day after the NCSC report, the group quickly ditched the malware approach in favor of mass-altering the DNS settings on thousands of vulnerable routers.
“Before the last NCSC report came out they used this capability in very limited instances,” Adamitis told KrebsOnSecurity. “After the report was released they implemented the capability in a more systemic fashion and used it to target everything that was vulnerable.”
TP-Link was among the router makers facing a complete ban in the United States. But on March 23, the U.S. Federal Communications Commission (FCC) took a much broader approach, announcing it would no longer certify consumer-grade Internet routers that are produced outside of the United States.
The FCC warned that foreign-made routers had become an untenable national security threat, and that poorly-secured routers present “a severe cybersecurity risk that could be leveraged to immediately and severely disrupt U.S. critical infrastructure and directly harm U.S. persons.”
Experts have countered that few new consumer-grade routers would be available for purchase under this new FCC policy (besides maybe Musk’s Starlink satellite Internet routers, which are produced in Texas). The FCC says router makers can apply for a special “conditional approval” from the Department of War or Department of Homeland Security, and that the new policy does not affect any previously-purchased consumer-grade routers.
Arnaque CySEC : le faux sauvetage après la fraude
Arnaque CySEC : le faux sauvetage après la fraude
KFC France alerte sur une fuite de données
Arnaque CySEC : le faux sauvetage après la fraude
KFC France alerte sur une fuite de données
KFC France alerte sur une fuite de données
Nissan face à une revendication explosive : 910 Go de données et des exports clients
KFC France alerte sur une fuite de données
Nissan face à une revendication explosive : 910 Go de données et des exports clients
Nissan face à une revendication explosive : 910 Go de données et des exports clients
Axios compromis : une attaque discrète au cœur du code
Germany Doxes “UNKN,” Head of RU Ransomware Gangs REvil, GandCrab
An elusive hacker who went by the handle “UNKN” and ran the early Russian ransomware groups GandCrab and REvil now has a name and a face. Authorities in Germany say 31-year-old Russian Daniil Maksimovich Shchukin headed both cybercrime gangs and helped carry out at least 130 acts of computer sabotage and extortion against victims across the country between 2019 and 2021.
Shchukin was named as UNKN (a.k.a. UNKNOWN) in an advisory published by the German Federal Criminal Police (the “Bundeskriminalamt” or BKA for short). The BKA said Shchukin and another Russian — 43-year-old Anatoly Sergeevitsch Kravchuk — extorted nearly $2 million euros across two dozen cyberattacks that caused more than 35 million euros in total economic damage.
Daniil Maksimovich SHCHUKIN, a.k.a. UNKN, and Anatoly Sergeevitsch Karvchuk, alleged leaders of the GandCrab and REvil ransomware groups.
Germany’s BKA said Shchukin acted as the head of one of the largest worldwide operating ransomware groups GandCrab and REvil, which pioneered the practice of double extortion — charging victims once for a key needed to unlock hacked systems, and a separate payment in exchange for a promise not to publish stolen data.
Shchukin’s name appeared in a Feb. 2023 filing (PDF) from the U.S. Justice Department seeking the seizure of various cryptocurrency accounts associated with proceeds from the REvil ransomware gang’s activities. The government said the digital wallet tied to Shchukin contained more than $317,000 in ill-gotten cryptocurrency.
The Gandcrab ransomware affiliate program first surfaced in January 2018, and paid enterprising hackers huge shares of the profits just for hacking into user accounts at major corporations. The Gandcrab team would then try to expand that access, often siphoning vast amounts of sensitive and internal documents in the process. The malware’s curators shipped five major revisions to the GandCrab code, each corresponding with sneaky new features and bug fixes aimed at thwarting the efforts of computer security firms to stymie the spread of the malware.
On May 31, 2019, the GandCrab team announced the group was shutting down after extorting more than $2 billion from victims. “We are a living proof that you can do evil and get off scot-free,” GandCrab’s farewell address famously quipped. “We have proved that one can make a lifetime of money in one year. We have proved that you can become number one by general admission, not in your own conceit.”
The REvil ransomware affiliate program materialized around the same as GandCrab’s demise, fronted by a user named UNKNOWN who announced on a Russian cybercrime forum that he’d deposited $1 million in the forum’s escrow to show he meant business. By this time, many cybersecurity experts had concluded REvil was little more than a reorganization of GandCrab.
UNKNOWN also gave an interview to Dmitry Smilyanets, a former malicious hacker hired by Recorded Future, wherein UNKNOWN described a rags-to-riches tale unencumbered by ethics and morals.
“As a child, I scrounged through the trash heaps and smoked cigarette butts,” UNKNOWN told Recorded Future. “I walked 10 km one way to the school. I wore the same clothes for six months. In my youth, in a communal apartment, I didn’t eat for two or even three days. Now I am a millionaire.”
As described in The Ransomware Hunting Team by Renee Dudley and Daniel Golden, UNKNOWN and REvil reinvested significant earnings into improving their success and mirroring practices of legitimate businesses. The authors wrote:
“Just as a real-world manufacturer might hire other companies to handle logistics or web design, ransomware developers increasingly outsourced tasks beyond their purview, focusing instead on improving the quality of their ransomware. The higher quality ransomware—which, in many cases, the Hunting Team could not break—resulted in more and higher pay-outs from victims. The monumental payments enabled gangs to reinvest in their enterprises. They hired more specialists, and their success accelerated.”
“Criminals raced to join the booming ransomware economy. Underworld ancillary service providers sprouted or pivoted from other criminal work to meet developers’ demand for customized support. Partnering with gangs like GandCrab, ‘cryptor’ providers ensured ransomware could not be detected by standard anti-malware scanners. ‘Initial access brokerages’ specialized in stealing credentials and finding vulnerabilities in target networks, selling that access to ransomware operators and affiliates. Bitcoin “tumblers” offered discounts to gangs that used them as a preferred vendor for laundering ransom payments. Some contractors were open to working with any gang, while others entered exclusive partnerships.”
REvil would evolve into a feared “big-game-hunting” machine capable of extracting hefty extortion payments from victims, largely going after organizations with more than $100 million in annual revenues and fat new cyber insurance policies that were known to pay out.
Over the July 4, 2021 weekend in the United States, REvil hacked into and extorted Kaseya, a company that handled IT operations for more than 1,500 businesses, nonprofits and government agencies. The FBI would later announce they’d infiltrated the ransomware group’s servers prior to the Kaseya hack but couldn’t tip their hand at the time. REvil never recovered from that core compromise, or from the FBI’s release of a free decryption key for REvil victims who couldn’t or didn’t pay.
Shchukin is from Krasnodar, Russia and is thought to reside there, the BKA said.
“Based on the investigations so far, it is assumed that the wanted person is abroad, presumably in Russia,” the BKA advised. “Travel behaviour cannot be ruled out.”
There is little that connects Shchukin to UNKNOWN’s various accounts on the Russian crime forums. But a review of the Russian crime forums indexed by the cyber intelligence firm Intel 471 shows there is plenty connecting Shchukin to a hacker identity called “Ger0in” who operated large botnets and sold “installs” — allowing other cybercriminals to rapidly deploy malware of their choice to thousands of PCs in one go. However, Ger0in was only active between 2010 and 2011, well before UNKNOWN’s appearance as the REvil front man.
A review of the mugshots released by the BKA at the image comparison site Pimeyes found a match on this birthday celebration from 2023, which features a young man named Daniel wearing the same fancy watch as in the BKA photos.
