Microsoft today issued security updates to fix at least 56 vulnerabilities in its Windows operating systems and supported software, including two zero-day flaws that are being actively exploited.

All supported Windows operating systems will receive an update this month for a buffer overflow vulnerability that carries the catchy name CVE-2025-21418. This patch should be a priority for enterprises, as Microsoft says it is being exploited, has low attack complexity, and no requirements for user interaction.

Tenable senior staff research engineer Satnam Narang noted that since 2022, there have been nine elevation of privilege vulnerabilities in this same Windows component — three each year — including one in 2024 that was exploited in the wild as a zero day (CVE-2024-38193).

“CVE-2024-38193 was exploited by the North Korean APT group known as Lazarus Group to implant a new version of the FudModule rootkit in order to maintain persistence and stealth on compromised systems,” Narang said. “At this time, it is unclear if CVE-2025-21418 was also exploited by Lazarus Group.”

The other zero-day, CVE-2025-21391, is an elevation of privilege vulnerability in Windows Storage that could be used to delete files on a targeted system. Microsoft’s advisory on this bug references something called “CWE-59: Improper Link Resolution Before File Access,” says no user interaction is required, and that the attack complexity is low.

Adam Barnett, lead software engineer at Rapid7, said although the advisory provides scant detail, and even offers some vague reassurance that ‘an attacker would only be able to delete targeted files on a system,’ it would be a mistake to assume that the impact of deleting arbitrary files would be limited to data loss or denial of service.

“As long ago as 2022, ZDI researchers set out how a motivated attacker could parlay arbitrary file deletion into full SYSTEM access using techniques which also involve creative misuse of symbolic links,”Barnett wrote.

One vulnerability patched today that was publicly disclosed earlier is CVE-2025-21377, another weakness that could allow an attacker to elevate their privileges on a vulnerable Windows system. Specifically, this is yet another Windows flaw that can be used to steal NTLMv2 hashes — essentially allowing an attacker to authenticate as the targeted user without having to log in.

According to Microsoft, minimal user interaction with a malicious file is needed to exploit CVE-2025-21377, including selecting, inspecting or “performing an action other than opening or executing the file.”

“This trademark linguistic ducking and weaving may be Microsoft’s way of saying ‘if we told you any more, we’d give the game away,'” Barnett said. “Accordingly, Microsoft assesses exploitation as more likely.”

The SANS Internet Storm Center has a handy list of all the Microsoft patches released today, indexed by severity. Windows enterprise administrators would do well to keep an eye on askwoody.com, which often has the scoop on any patches causing problems.

It’s getting harder to buy Windows software that isn’t also bundled with Microsoft’s flagship Copilot artificial intelligence (AI) feature. Last month Microsoft started bundling Copilot with Microsoft Office 365, which Redmond has since rebranded as “Microsoft 365 Copilot.” Ostensibly to offset the costs of its substantial AI investments, Microsoft also jacked up prices from 22 percent to 30 percent for upcoming license renewals and new subscribers.

Office-watch.com writes that existing Office 365 users who are paying an annual cloud license do have the option of “Microsoft 365 Classic,” an AI-free subscription at a lower price, but that many customers are not offered the option until they attempt to cancel their existing Office subscription.

In other security patch news, Apple has shipped iOS 18.3.1, which fixes a zero day vulnerability (CVE-2025-24200) that is showing up in attacks.

Adobe has issued security updates that fix a total of 45 vulnerabilities across InDesign, Commerce, Substance 3D Stager, InCopy, Illustrator, Substance 3D Designer and Photoshop Elements.

Chris Goettl at Ivanti notes that Google Chrome is shipping an update today which will trigger updates for Chromium based browsers including Microsoft Edge, so be on the lookout for Chrome and Edge updates as we proceed through the week.

Image: Shutterstock, ArtHead.

In an effort to blend in and make their malicious traffic tougher to block, hosting firms catering to cybercriminals in China and Russia increasingly are funneling their operations through major U.S. cloud providers. Research published this week on one such outfit — a sprawling network tied to Chinese organized crime gangs and aptly named “Funnull” — highlights a persistent whac-a-mole problem facing cloud services.

In October 2024, the security firm Silent Push published a lengthy analysis of how Amazon AWS and Microsoft Azure were providing services to Funnull, a two-year-old Chinese content delivery network that hosts a wide variety of fake trading apps, pig butchering scams, gambling websites, and retail phishing pages.

Funnull made headlines last summer after it acquired the domain name polyfill[.]io, previously the home of a widely-used open source code library that allowed older browsers to handle advanced functions that weren’t natively supported. There were still tens of thousands of legitimate domains linking to the Polyfill domain at the time of its acquisition, and Funnull soon after conducted a supply-chain attack that redirected visitors to malicious sites.

Silent Push’s October 2024 report found a vast number of domains hosted via Funnull promoting gambling sites that bear the logo of the Suncity Group, a Chinese entity named in a 2024 UN report (PDF) for laundering millions of dollars for the North Korean Lazarus Group.

In 2023, Suncity’s CEO was sentenced to 18 years in prison on charges of fraud, illegal gambling, and “triad offenses,” i.e. working with Chinese transnational organized crime syndicates. Suncity is alleged to have built an underground banking system that laundered billions of dollars for criminals.

It is likely the gambling sites coming through Funnull are abusing top casino brands as part of their money laundering schemes. In reporting on Silent Push’s October report, TechCrunch obtained a comment from Bwin, one of the casinos being advertised en masse through Funnull, and Bwin said those websites did not belong to them.

Gambling is illegal in China except in Macau, a special administrative region of China. Silent Push researchers say Funnull may be helping online gamblers in China evade the Communist party’s “Great Firewall,” which blocks access to gambling destinations.

Silent Push’s Zach Edwards said that upon revisiting Funnull’s infrastructure again this month, they found dozens of the same Amazon and Microsoft cloud Internet addresses still forwarding Funnull traffic through a dizzying chain of auto-generated domain names before redirecting malicious or phishous websites.

Edwards said Funnull is a textbook example of an increasing trend Silent Push calls “infrastructure laundering,” wherein crooks selling cybercrime services will relay some or all of their malicious traffic through U.S. cloud providers.

“It’s crucial for global hosting companies based in the West to wake up to the fact that extremely low quality and suspicious web hosts based out of China are deliberately renting IP space from multiple companies and then mapping those IPs to their criminal client websites,” Edwards told KrebsOnSecurity. “We need these major hosts to create internal policies so that if they are renting IP space to one entity, who further rents it to host numerous criminal websites, all of those IPs should be reclaimed and the CDN who purchased them should be banned from future IP rentals or purchases.”

A Suncity gambling site promoted via Funnull. The sites feature a prompt for a Tether/USDT deposit program.

Reached for comment, Amazon referred this reporter to a statement Silent Push included in a report released today. Amazon said AWS was already aware of the Funnull addresses tracked by Silent Push, and that it had suspended all known accounts linked to the activity.

Amazon said that contrary to implications in the Silent Push report, it has every reason to aggressively police its network against this activity, noting the accounts tied to Funnull used “fraudulent methods to temporarily acquire infrastructure, for which it never pays. Thus, AWS incurs damages as a result of the abusive activity.”

“When AWS’s automated or manual systems detect potential abuse, or when we receive reports of potential abuse, we act quickly to investigate and take action to stop any prohibited activity,” Amazon’s statement continues. “In the event anyone suspects that AWS resources are being used for abusive activity, we encourage them to report it to AWS Trust & Safety using the report abuse form. In this case, the authors of the report never notified AWS of the findings of their research via our easy-to-find security and abuse reporting channels. Instead, AWS first learned of their research from a journalist to whom the researchers had provided a draft.”

Microsoft likewise said it takes such abuse seriously, and encouraged others to report suspicious activity found on its network.

“We are committed to protecting our customers against this kind of activity and actively enforce acceptable use policies when violations are detected,” Microsoft said in a written statement. “We encourage reporting suspicious activity to Microsoft so we can investigate and take appropriate actions.”

Richard Hummel is threat intelligence lead at NETSCOUT. Hummel said it used to be that “noisy” and frequently disruptive malicious traffic — such as automated application layer attacks, and “brute force” efforts to crack passwords or find vulnerabilities in websites — came mostly from botnets, or large collections of hacked devices.

But he said the vast majority of the infrastructure used to funnel this type of traffic is now proxied through major cloud providers, which can make it difficult for organizations to block at the network level.

“From a defenders point of view, you can’t wholesale block cloud providers, because a single IP can host thousands or tens of thousands of domains,” Hummel said.

In May 2024, KrebsOnSecurity published a deep dive on Stark Industries Solutions, an ISP that materialized at the start of Russia’s invasion of Ukraine and has been used as a global proxy network that conceals the true source of cyberattacks and disinformation campaigns against enemies of Russia. Experts said much of the malicious traffic  traversing Stark’s network (e.g. vulnerability scanning and password brute force attacks) was being bounced through U.S.-based cloud providers.

Stark’s network has been a favorite of the Russian hacktivist group called NoName057(16), which frequently launches huge distributed denial-of-service (DDoS) attacks against a variety of targets seen as opposed to Moscow. Hummel said NoName’s history suggests they are adept at cycling through new cloud provider accounts, making anti-abuse efforts into a game of whac-a-mole.

“It almost doesn’t matter if the cloud provider is on point and takes it down because the bad guys will just spin up a new one,” he said. “Even if they’re only able to use it for an hour, they’ve already done their damage. It’s a really difficult problem.”

Edwards said Amazon declined to specify whether the banned Funnull users were operating using compromised accounts or stolen payment card data, or something else.

“I’m surprised they wanted to lean into ‘We’ve caught this 1,200+ times and have taken these down!’ and yet didn’t connect that each of those IPs was mapped to [the same] Chinese CDN,” he said. “We’re just thankful Amazon confirmed that account mules are being used for this and it isn’t some front-door relationship. We haven’t heard the same thing from Microsoft but it’s very likely that the same thing is happening.”

Funnull wasn’t always a bulletproof hosting network for scam sites. Prior to 2022, the network was known as Anjie CDN, based in the Philippines. One of Anjie’s properties was a website called funnull[.]app. Loading that domain reveals a pop-up message by the original Anjie CDN owner, who said their operations had been seized by an entity known as Fangneng CDN and ACB Group, the parent company of Funnull.

A machine-translated message from the former owner of Anjie CDN, a Chinese content delivery network that is now Funnull.

“After I got into trouble, the company was managed by my family,” the message explains. “Because my family was isolated and helpless, they were persuaded by villains to sell the company. Recently, many companies have contacted my family and threatened them, believing that Fangneng CDN used penetration and mirroring technology through customer domain names to steal member information and financial transactions, and stole customer programs by renting and selling servers. This matter has nothing to do with me and my family. Please contact Fangneng CDN to resolve it.”

In January 2024, the U.S. Department of Commerce issued a proposed rule that would require cloud providers to create a “Customer Identification Program” that includes procedures to collect data sufficient to determine whether each potential customer is a foreign or U.S. person.

According to the law firm Crowell & Moring LLP, the Commerce rule also would require “infrastructure as a service” (IaaS) providers to report knowledge of any transactions with foreign persons that might allow the foreign entity to train a large AI model with potential capabilities that could be used in malicious cyber-enabled activity.

“The proposed rulemaking has garnered global attention, as its cross-border data collection requirements are unprecedented in the cloud computing space,” Crowell wrote. “To the extent the U.S. alone imposes these requirements, there is concern that U.S. IaaS providers could face a competitive disadvantage, as U.S. allies have not yet announced similar foreign customer identification requirements.”

It remains unclear if the new White House administration will push forward with the requirements. The Commerce action was mandated as part of an executive order President Trump issued a day before leaving office in January 2021.

Microsoft today unleashed updates to plug a whopping 161 security vulnerabilities in Windows and related software, including three “zero-day” weaknesses that are already under active attack. Redmond’s inaugural Patch Tuesday of 2025 bundles more fixes than the company has shipped in one go since 2017.

Rapid7‘s Adam Barnett says January marks the fourth consecutive month where Microsoft has published zero-day vulnerabilities on Patch Tuesday without evaluating any of them as critical severity at time of publication. Today also saw the publication of nine critical remote code execution (RCE) vulnerabilities.

The Microsoft flaws already seeing active attacks include CVE-2025-21333, CVE-2025-21334 and, you guessed it– CVE-2025-21335. These are sequential because all reside in Windows Hyper-V, a component that is heavily embedded in modern Windows 11 operating systems and used for security features including device guard and credential guard.

Tenable’s Satnam Narang says little is known about the in-the-wild exploitation of these flaws, apart from the fact that they are all “privilege escalation” vulnerabilities. Narang said we tend to see a lot of elevation of privilege bugs exploited in the wild as zero-days in Patch Tuesday because it’s not always initial access to a system that’s a challenge for attackers as they have various avenues in their pursuit.

“As elevation of privilege bugs, they’re being used as part of post-compromise activity, where an attacker has already accessed a target system,” he said. “It’s kind of like if an attacker is able to enter a secure building, they’re unable to access more secure parts of the facility because they have to prove that they have clearance. In this case, they’re able to trick the system into believing they should have clearance.”

Several bugs addressed today earned CVSS (threat rating) scores of 9.8 out of a possible 10, including CVE-2025-21298, a weakness in Windows that could allow attackers to run arbitrary code by getting a target to open a malicious .rtf file, documents typically opened on Office applications like Microsoft Word. Microsoft has rated this flaw “exploitation more likely.”

Ben Hopkins at Immersive Labs called attention to the CVE-2025-21311, a 9.8 “critical” bug in Windows NTLMv1 (NT LAN Manager version 1), an older Microsoft authentication protocol that is still used by many organizations.

“What makes this vulnerability so impactful is the fact that it is remotely exploitable, so attackers can reach the compromised machine(s) over the internet, and the attacker does not need significant knowledge or skills to achieve repeatable success with the same payload across any vulnerable component,” Hopkins wrote.

Kev Breen at Immersive points to an interesting flaw (CVE-2025-21210) that Microsoft fixed in its full disk encryption suite Bitlocker that the software giant has dubbed “exploitation more likely.” Specifically, this bug holds out the possibility that in some situations the hibernation image created when one closes the laptop lid on an open Windows session may not be fully encrypted and could be recovered in plain text.

“Hibernation images are used when a laptop goes to sleep and contains the contents that were stored in RAM at the moment the device powered down,” Breen noted. “This presents a significant potential impact as RAM can contain sensitive data (such as passwords, credentials and PII) that may have been in open documents or browser sessions and can all be recovered with free tools from hibernation files.”

Tenable’s Narang also highlighted a trio of vulnerabilities in Microsoft Access fixed this month and credited to Unpatched.ai, a security research effort that is aided by artificial intelligence looking for vulnerabilities in code. Tracked as CVE-2025-21186, CVE-2025-21366, and CVE-2025-21395, these are remote code execution bugs that are exploitable if an attacker convinces a target to download and run a malicious file through social engineering. Unpatched.ai was also credited with discovering a flaw in the December 2024 Patch Tuesday release (CVE-2024-49142).

“Automated vulnerability detection using AI has garnered a lot of attention recently, so it’s noteworthy to see this service being credited with finding bugs in Microsoft products,” Narang observed. “It may be the first of many in 2025.”

If you’re a Windows user who has automatic updates turned off and haven’t updated in a while, it’s probably time to play catch up. Please consider backing up important files and/or the entire hard drive before updating. And if you run into any problems installing this month’s patch batch, drop a line in the comments below, please.

Further reading on today’s patches from Microsoft:

Tenable blog

SANS Internet Storm Center

Ask Woody