Krebs on Security

The Cloudflare Outage May Be a Security Roadmap

November 19, 2025

An intermittent outage at Cloudflare on Tuesday briefly knocked many of the Internet’s top destinations offline. Some affected Cloudflare customers were able to pivot away from the platform temporarily so that visitors could still access their websites. But security experts say doing so may have also triggered an impromptu network penetration test for organizations that have come to rely on Cloudflare to block many types of abusive and malicious traffic.

At around 6:30 EST/11:30 UTC on Nov. 18, Cloudflare’s status page acknowledged the company was experiencing “an internal service degradation.” After several hours of Cloudflare services coming back up and failing again, many websites behind Cloudflare found they could not migrate away from using the company’s services because the Cloudflare portal was unreachable and/or because they also were getting their domain name system (DNS) services from Cloudflare.

However, some customers did manage to pivot their domains away from Cloudflare during the outage. And many of those organizations probably need to take a closer look at their web application firewall (WAF) logs during that time, said Aaron Turner, a faculty member at IANS Research.

Turner said Cloudflare’s WAF does a good job filtering out malicious traffic that matches any one of the top ten types of application-layer attacks, including credential stuffing, cross-site scripting, SQL injection, bot attacks and API abuse. But he said this outage might be a good opportunity for Cloudflare customers to better understand how their own app and website defenses may be failing without Cloudflare’s help.

“Your developers could have been lazy in the past for SQL injection because Cloudflare stopped that stuff at the edge,” Turner said. “Maybe you didn’t have the best security QA [quality assurance] for certain things because Cloudflare was the control layer to compensate for that.”

Turner said one company he’s working with saw a huge increase in log volume and they are still trying to figure out what was “legit malicious” versus just noise.

“It looks like there was about an eight hour window when several high-profile sites decided to bypass Cloudflare for the sake of availability,” Turner said. “Many companies have essentially relied on Cloudflare for the OWASP Top Ten [web application vulnerabilities] and a whole range of bot blocking. How much badness could have happened in that window? Any organization that made that decision needs to look closely at any exposed infrastructure to see if they have someone persisting after they’ve switched back to Cloudflare protections.” Continue reading →

Microsoft Patch Tuesday, November 2025 Edition

November 16, 2025

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Microsoft this week pushed security updates to fix more than 60 vulnerabilities in its Windows operating systems and supported software, including at least one zero-day bug that is already being exploited. Microsoft also fixed a glitch that prevented some Windows 10 users from taking advantage of an extra year of security updates, which is nice because the zero-day flaw and other critical weaknesses affect all versions of Windows, including Windows 10.

Affected products this month include the Windows OS, Office, SharePoint, SQL Server, Visual Studio, GitHub Copilot, and Azure Monitor Agent. The zero-day threat concerns a memory corruption bug deep in the Windows innards called CVE-2025-62215. Despite the flaw’s zero-day status, Microsoft has assigned it an “important” rating rather than critical, because exploiting it requires an attacker to already have access to the target’s device.

“These types of vulnerabilities are often exploited as part of a more complex attack chain,” said Johannes Ullrich, dean of research for the SANS Technology Institute. “However, exploiting this specific vulnerability is likely to be relatively straightforward, given the existence of prior similar vulnerabilities.”

Ben McCarthy, lead cybersecurity engineer at Immersive, called attention to CVE-2025-60274, a critical weakness in a core Windows graphic component (GDI+) that is used by a massive number of applications, including Microsoft Office, web servers processing images, and countless third-party applications.

“The patch for this should be an organization’s highest priority,” McCarthy said. “While Microsoft assesses this as ‘Exploitation Less Likely,’ a 9.8-rated flaw in a ubiquitous library like GDI+ is a critical risk.”

Microsoft patched a critical bug in Office — CVE-2025-62199 — that can lead to remote code execution on a Windows system. Alex Vovk, CEO and co-founder of Action1, said this Office flaw is a high priority because it is low complexity, needs no privileges, and can be exploited just by viewing a booby-trapped message in the Preview Pane. Continue reading →

Google Sues to Disrupt Chinese SMS Phishing Triad

November 13, 2025

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Google is suing more than two dozen unnamed individuals allegedly involved in peddling a popular China-based mobile phishing service that helps scammers impersonate hundreds of trusted brands, blast out text message lures, and convert phished payment card data into mobile wallets from Apple and Google.

In a lawsuit filed in the Southern District of New York on November 12, Google sued to unmask and disrupt 25 “John Doe” defendants allegedly linked to the sale of Lighthouse, a sophisticated phishing kit that makes it simple for even novices to steal payment card data from mobile users. Google said Lighthouse has harmed more than a million victims across 120 countries.

A component of the Chinese phishing kit Lighthouse made to target customers of The Toll Roads, which refers to several state routes through Orange County, Calif.

Lighthouse is one of several prolific phishing-as-a-service operations known as the “Smishing Triad,” and collectively they are responsible for sending millions of text messages that spoof the U.S. Postal Service to supposedly collect some outstanding delivery fee, or that pretend to be a local toll road operator warning of a delinquent toll fee. More recently, Lighthouse has been used to spoof e-commerce websites, financial institutions and brokerage firms.

Regardless of the text message lure used or brand used, the basic scam remains the same: After the visitor enters their payment information, the phishing site will automatically attempt to enroll the card as a mobile wallet from Apple or Google. The phishing site then tells the visitor that their bank is going to verify the transaction by sending a one-time code that needs to be entered into the payment page before the transaction can be completed.

If the recipient provides that one-time code, the scammers can link the victim’s card data to a mobile wallet on a device that they control. Researchers say the fraudsters usually load several stolen wallets onto each mobile device, and wait 7-10 days after that enrollment before selling the phones or using them for fraud.

Google called the scale of the Lighthouse phishing attacks “staggering.” A May 2025 report from Silent Push found the domains used by the Smishing Triad are rotated frequently, with approximately 25,000 phishing domains active during any 8-day period.

Google’s lawsuit alleges the purveyors of Lighthouse violated the company’s trademarks by including Google’s logos on countless phishing websites. The complaint says Lighthouse offers over 600 templates for phishing websites of more than 400 entities, and that Google’s logos were featured on at least a quarter of those templates.

Google is also pursuing Lighthouse under the Racketeer Influenced and Corrupt Organizations (RICO) Act, saying the Lighthouse phishing enterprise encompasses several connected threat actor groups that work together to design and implement complex criminal schemes targeting the general public.

According to Google, those threat actor teams include a “developer group” that supplies the phishing software and templates; a “data broker group” that provides a list of targets; a “spammer group” that provides the tools to send fraudulent text messages in volume; a “theft group,” in charge of monetizing the phished information; and an “administrative group,” which runs their Telegram support channels and discussion groups designed to facilitate collaboration and recruit new members.

“While different members of the Enterprise may play different roles in the Schemes, they all collaborate to execute phishing attacks that rely on the Lighthouse software,” Google’s complaint alleges. “None of the Enterprise’s Schemes can generate revenue without collaboration and cooperation among the members of the Enterprise. All of the threat actor groups are connected to one another through historical and current business ties, including through their use of Lighthouse and the online community supporting its use, which exists on both YouTube and Telegram channels.”

Silent Push’s May report observed that the Smishing Triad boasts it has “300+ front desk staff worldwide” involved in Lighthouse, staff that is mainly used to support various aspects of the group’s fraud and cash-out schemes.

An image shared by an SMS phishing group shows a panel of mobile phones responsible for mass-sending phishing messages. These panels require a live operator because the one-time codes being shared by phishing victims must be used quickly as they generally expire within a few minutes.

Continue reading →

Drilling Down on Uncle Sam’s Proposed TP-Link Ban

November 9, 2025

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The U.S. government is reportedly preparing to ban the sale of wireless routers and other networking gear from TP-Link Systems, a tech company that currently enjoys an estimated 50% market share among home users and small businesses. Experts say while the proposed ban may have more to do with TP-Link’s ties to China than any specific technical threats, much of the rest of the industry serving this market also sources hardware from China and ships products that are insecure fresh out of the box.

A TP-Link WiFi 6 AX1800 Smart WiFi Router (Archer AX20).

The Washington Post recently reported that more than a half-dozen federal departments and agencies were backing a proposed ban on future sales of TP-Link devices in the United States. The story said U.S. Department of Commerce officials concluded TP-Link Systems products pose a risk because the U.S.-based company’s products handle sensitive American data and because the officials believe it remains subject to jurisdiction or influence by the Chinese government.

TP-Link Systems denies that, saying that it fully split from the Chinese TP-Link Technologies over the past three years, and that its critics have vastly overstated the company’s market share (TP-Link puts it at around 30 percent). TP-Link says it has headquarters in California, with a branch in Singapore, and that it manufactures in Vietnam. The company says it researches, designs, develops and manufactures everything except its chipsets in-house.

TP-Link Systems told The Post it has sole ownership of some engineering, design and manufacturing capabilities in China that were once part of China-based TP-Link Technologies, and that it operates them without Chinese government supervision.

“TP-Link vigorously disputes any allegation that its products present national security risks to the United States,” Ricca Silverio, a spokeswoman for TP-Link Systems, said in a statement. “TP-Link is a U.S. company committed to supplying high-quality and secure products to the U.S. market and beyond.”

Cost is a big reason TP-Link devices are so prevalent in the consumer and small business market: As this February 2025 story from Wired observed regarding the proposed ban, TP-Link has long had a reputation for flooding the market with devices that are considerably cheaper than comparable models from other vendors. That price point (and consistently excellent performance ratings) has made TP-Link a favorite among Internet service providers (ISPs) that provide routers to their customers.

In August 2024, the chairman and the ranking member of the House Select Committee on the Strategic Competition Between the United States and the Chinese Communist Party called for an investigation into TP-Link devices, which they said were found on U.S. military bases and for sale at exchanges that sell them to members of the military and their families.

“TP-Link’s unusual degree of vulnerabilities and required compliance with PRC law are in and of themselves disconcerting,” the House lawmakers warned in a letter (PDF) to the director of the Commerce Department. “When combined with the PRC government’s common use of SOHO [small office/home office] routers like TP-Link to perpetrate extensive cyberattacks in the United States, it becomes significantly alarming.”

The letter cited a May 2023 blog post by Check Point Research about a Chinese state-sponsored hacking group dubbed “Camaro Dragon” that used a malicious firmware implant for some TP-Link routers to carry out a sequence of targeted cyberattacks against European foreign affairs entities. Check Point said while it only found the malicious firmware on TP-Link devices, “the firmware-agnostic nature of the implanted components indicates that a wide range of devices and vendors may be at risk.”

In a report published in October 2024, Microsoft said it was tracking a network of compromised TP-Link small office and home office routers that has been abused by multiple distinct Chinese state-sponsored hacking groups since 2021. Microsoft found the hacker groups were leveraging the compromised TP-Link systems to conduct “password spraying” attacks against Microsoft accounts. Password spraying involves rapidly attempting to access a large number of accounts (usernames/email addresses) with a relatively small number of commonly used passwords.

TP-Link rightly points out that most of its competitors likewise source components from China. The company also correctly notes that advanced persistent threat (APT) groups from China and other nations have leveraged vulnerabilities in products from their competitors, such as Cisco and Netgear.

But that may be cold comfort for TP-Link customers who are now wondering if it’s smart to continue using these products, or whether it makes sense to buy more costly networking gear that might only be marginally less vulnerable to compromise. Continue reading →

Cloudflare Scrubs Aisuru Botnet from Top Domains List

November 5, 2025

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For the past week, domains associated with the massive Aisuru botnet have repeatedly usurped Amazon, Apple, Google and Microsoft in Cloudflare’s public ranking of the most frequently requested websites. Cloudflare responded by redacting Aisuru domain names from their top websites list. The chief executive at Cloudflare says Aisuru’s overlords are using the botnet to boost their malicious domain rankings, while simultaneously attacking the company’s domain name system (DNS) service.

The #1 and #3 positions in this chart are Aisuru botnet controllers with their full domain names redacted. Source: radar.cloudflare.com.

Aisuru is a rapidly growing botnet comprising hundreds of thousands of hacked Internet of Things (IoT) devices, such as poorly secured Internet routers and security cameras. The botnet has increased in size and firepower significantly since its debut in 2024, demonstrating the ability to launch record distributed denial-of-service (DDoS) attacks nearing 30 terabits of data per second.

Until recently, Aisuru’s malicious code instructed all infected systems to use DNS servers from Google — specifically, the servers at 8.8.8.8. But in early October, Aisuru switched to invoking Cloudflare’s main DNS server — 1.1.1.1 — and over the past week domains used by Aisuru to control infected systems started populating Cloudflare’s top domain rankings.

As screenshots of Aisuru domains claiming two of the Top 10 positions ping-ponged across social media, many feared this was yet another sign that an already untamable botnet was running completely amok. One Aisuru botnet domain that sat prominently for days at #1 on the list was someone’s street address in Massachusetts followed by “.com”. Other Aisuru domains mimicked those belonging to major cloud providers.

Cloudflare tried to address these security, brand confusion and privacy concerns by partially redacting the malicious domains, and adding a warning at the top of its rankings:

“Note that the top 100 domains and trending domains lists include domains with organic activity as well as domains with emerging malicious behavior.”

Cloudflare CEO Matthew Prince told KrebsOnSecurity the company’s domain ranking system is fairly simplistic, and that it merely measures the volume of DNS queries to 1.1.1.1.

“The attacker is just generating a ton of requests, maybe to influence the ranking but also to attack our DNS service,” Prince said, adding that Cloudflare has heard reports of other large public DNS services seeing similar uptick in attacks. “We’re fixing the ranking to make it smarter. And, in the meantime, redacting any sites we classify as malware.” Continue reading →

Alleged Jabber Zeus Coder ‘MrICQ’ in U.S. Custody

November 2, 2025

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A Ukrainian man indicted in 2012 for conspiring with a prolific hacking group to steal tens of millions of dollars from U.S. businesses was arrested in Italy and is now in custody in the United States, KrebsOnSecurity has learned.

Sources close to the investigation say Yuriy Igorevich Rybtsov, a 41-year-old from the Russia-controlled city of Donetsk, Ukraine, was previously referenced in U.S. federal charging documents only by his online handle “MrICQ.” According to a 13-year-old indictment (PDF) filed by prosecutors in Nebraska, MrICQ was a developer for a cybercrime group known as “Jabber Zeus.”

Image: lockedup dot wtf.

The Jabber Zeus name is derived from the malware they used — a custom version of the ZeuS banking trojan — that stole banking login credentials and would send the group a Jabber instant message each time a new victim entered a one-time passcode at a financial institution website. The gang targeted mostly small to mid-sized businesses, and they were an early pioneer of so-called “man-in-the-browser” attacks, malware that can silently intercept any data that victims submit in a web-based form.

Once inside a victim company’s accounts, the Jabber Zeus crew would modify the firm’s payroll to add dozens of “money mules,” people recruited through elaborate work-at-home schemes to handle bank transfers. The mules in turn would forward any stolen payroll deposits — minus their commissions — via wire transfers to other mules in Ukraine and the United Kingdom.

The 2012 indictment targeting the Jabber Zeus crew named MrICQ as “John Doe #3,” and said this person handled incoming notifications of newly compromised victims. The Department of Justice (DOJ) said MrICQ also helped the group launder the proceeds of their heists through electronic currency exchange services.

Two sources familiar with the Jabber Zeus investigation said Rybtsov was arrested in Italy, although the exact date and circumstances of his arrest remain unclear. A summary of recent decisions (PDF) published by the Italian Supreme Court states that in April 2025, Rybtsov lost a final appeal to avoid extradition to the United States.

According to the mugshot website lockedup[.]wtf, Rybtsov arrived in Nebraska on October 9, and was being held under an arrest warrant from the U.S. Federal Bureau of Investigation (FBI).

The data breach tracking service Constella Intelligence found breached records from the business profiling site bvdinfo[.]com showing that a 41-year-old Yuriy Igorevich Rybtsov worked in a building at 59 Barnaulska St. in Donetsk. Further searching on this address in Constella finds the same apartment building was shared by a business registered to Vyacheslav “Tank” Penchukov, the leader of the Jabber Zeus crew in Ukraine.

Vyacheslav “Tank” Penchukov, seen here performing as “DJ Slava Rich” in Ukraine, in an undated photo from social media.

Penchukov was arrested in 2022 while traveling to meet his wife in Switzerland. Last year, a federal court in Nebraska sentenced Penchukov to 18 years in prison and ordered him to pay more than $73 million in restitution. Continue reading →

Aisuru Botnet Shifts from DDoS to Residential Proxies

October 28, 2025

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Aisuru, the botnet responsible for a series of record-smashing distributed denial-of-service (DDoS) attacks this year, recently was overhauled to support a more low-key, lucrative and sustainable business: Renting hundreds of thousands of infected Internet of Things (IoT) devices to proxy services that help cybercriminals anonymize their traffic. Experts say a glut of proxies from Aisuru and other sources is fueling large-scale data harvesting efforts tied to various artificial intelligence (AI) projects, helping content scrapers evade detection by routing their traffic through residential connections that appear to be regular Internet users.

First identified in August 2024, Aisuru has spread to at least 700,000 IoT systems, such as poorly secured Internet routers and security cameras. Aisuru’s overlords have used their massive botnet to clobber targets with headline-grabbing DDoS attacks, flooding targeted hosts with blasts of junk requests from all infected systems simultaneously.

In June, Aisuru hit KrebsOnSecurity.com with a DDoS clocking at 6.3 terabits per second — the biggest attack that Google had ever mitigated at the time. In the weeks and months that followed, Aisuru’s operators demonstrated DDoS capabilities of nearly 30 terabits of data per second — well beyond the attack mitigation capabilities of most Internet destinations.

These digital sieges have been particularly disruptive this year for U.S.-based Internet service providers (ISPs), in part because Aisuru recently succeeded in taking over a large number of IoT devices in the United States. And when Aisuru launches attacks, the volume of outgoing traffic from infected systems on these ISPs is often so high that it can disrupt or degrade Internet service for adjacent (non-botted) customers of the ISPs.

“Multiple broadband access network operators have experienced significant operational impact due to outbound DDoS attacks in excess of 1.5Tb/sec launched from Aisuru botnet nodes residing on end-customer premises,” wrote Roland Dobbins, principal engineer at Netscout, in a recent executive summary on Aisuru. “Outbound/crossbound attack traffic exceeding 1Tb/sec from compromised customer premise equipment (CPE) devices has caused significant disruption to wireline and wireless broadband access networks. High-throughput attacks have caused chassis-based router line card failures.”

The incessant attacks from Aisuru have caught the attention of federal authorities in the United States and Europe (many of Aisuru’s victims are customers of ISPs and hosting providers based in Europe). Quite recently, some of the world’s largest ISPs have started informally sharing block lists identifying the rapidly shifting locations of the servers that the attackers use to control the activities of the botnet.

Experts say the Aisuru botmasters recently updated their malware so that compromised devices can more easily be rented to so-called “residential proxy” providers. These proxy services allow paying customers to route their Internet communications through someone else’s device, providing anonymity and the ability to appear as a regular Internet user in almost any major city worldwide.

From a website’s perspective, the IP traffic of a residential proxy network user appears to originate from the rented residential IP address, not from the proxy service customer. Proxy services can be used in a legitimate manner for several business purposes — such as price comparisons or sales intelligence. But they are massively abused for hiding cybercrime activity (think advertising fraud, credential stuffing) because they can make it difficult to trace malicious traffic to its original source.

And as we’ll see in a moment, this entire shadowy industry appears to be shifting its focus toward enabling aggressive content scraping activity that continuously feeds raw data into large language models (LLMs) built to support various AI projects.

‘INSANE’ GROWTH

Riley Kilmer is co-founder of spur.us, a service that tracks proxy networks. Kilmer said all of the top proxy services have grown substantially over the past six months.

“I just checked, and in the last 90 days we’ve seen 250 million unique residential proxy IPs,” Kilmer said. “That is insane. That is so high of a number, it’s unheard of. These proxies are absolutely everywhere now.”

Today, Spur says it is tracking an unprecedented spike in available proxies across all providers, including;

LUMINATI_PROXY 11,856,421
NETNUT_PROXY 10,982,458
ABCPROXY_PROXY 9,294,419
OXYLABS_PROXY 6,754,790
IPIDEA_PROXY 3,209,313
EARNFM_PROXY 2,659,913
NODEMAVEN_PROXY 2,627,851
INFATICA_PROXY 2,335,194
IPROYAL_PROXY 2,032,027
YILU_PROXY 1,549,155 Continue reading →

Canada Fines Cybercrime Friendly Cryptomus $176M

October 22, 2025

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Financial regulators in Canada this week levied $176 million in fines against Cryptomus, a digital payments platform that supports dozens of Russian cryptocurrency exchanges and websites hawking cybercrime services. The penalties for violating Canada’s anti money-laundering laws come ten months after KrebsOnSecurity noted that Cryptomus’s Vancouver street address was home to dozens of foreign currency dealers, money transfer businesses, and cryptocurrency exchanges — none of which were physically located there.

On October 16, the Financial Transactions and Reports Analysis Center of Canada (FINTRAC) imposed a $176,960,190 penalty on Xeltox Enterprises Ltd., more commonly known as the cryptocurrency payments platform Cryptomus.

FINTRAC found that Cryptomus failed to submit suspicious transaction reports in cases where there were reasonable grounds to suspect that they were related to the laundering of proceeds connected to trafficking in child sexual abuse material, fraud, ransomware payments and sanctions evasion.

“Given that numerous violations in this case were connected to trafficking in child sexual abuse material, fraud, ransomware payments and sanctions evasion, FINTRAC was compelled to take this unprecedented enforcement action,” said Sarah Paquet, director and CEO at the regulatory agency.

In December 2024, KrebsOnSecurity covered research by blockchain analyst and investigator Richard Sanders, who’d spent several months signing up for various cybercrime services, and then tracking where their customer funds go from there. The 122 services targeted in Sanders’s research all used Cryptomus, and included some of the more prominent businesses advertising on the cybercrime forums, such as:

-abuse-friendly or “bulletproof” hosting providers like anonvm[.]wtf, and PQHosting;
-sites selling aged email, financial, or social media accounts, such as verif[.]work and kopeechka[.]store;
-anonymity or “proxy” providers like crazyrdp[.]com and rdp[.]monster;
-anonymous SMS services, including anonsim[.]net and smsboss[.]pro.

Flymoney, one of dozens of cryptocurrency exchanges apparently nested at Cryptomus. The image from this website has been machine translated from Russian.

Sanders found at least 56 cryptocurrency exchanges were using Cryptomus to process transactions, including financial entities with names like casher[.]su, grumbot[.]com, flymoney[.]biz, obama[.]ru and swop[.]is.

“These platforms were built for Russian speakers, and they each advertised the ability to anonymously swap one form of cryptocurrency for another,” the December 2024 story noted. “They also allowed the exchange of cryptocurrency for cash in accounts at some of Russia’s largest banks — nearly all of which are currently sanctioned by the United States and other western nations.”

Reached for comment on FINTRAC’s action, Sanders told KrebsOnSecurity he was surprised it took them so long.

“I have no idea why they don’t just sanction them or prosecute them,” Sanders said. “I’m not let down with the fine amount but it’s also just going to be the cost of doing business to them.” Continue reading →

Email Bombs Exploit Lax Authentication in Zendesk

October 17, 2025

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Cybercriminals are abusing a widespread lack of authentication in the customer service platform Zendesk to flood targeted email inboxes with menacing messages that come from hundreds of Zendesk corporate customers simultaneously.

Zendesk is an automated help desk service designed to make it simple for people to contact companies for customer support issues. Earlier this week, KrebsOnSecurity started receiving thousands of ticket creation notification messages through Zendesk in rapid succession, each bearing the name of different Zendesk customers, such as CapCom, CompTIA, Discord, GMAC, NordVPN, The Washington Post, and Tinder.

The abusive missives sent via Zendesk’s platform can include any subject line chosen by the abusers. In my case, the messages variously warned about a supposed law enforcement investigation involving KrebsOnSecurity.com, or else contained personal insults.

Moreover, the automated messages that are sent out from this type of abuse all come from customer domain names — not from Zendesk. In the example below, replying to any of the junk customer support responses from The Washington Post’s Zendesk installation shows the reply-to address is help@washpost.com.

One of dozens of messages sent to me this week by The Washington Post.

Notified about the mass abuse of their platform, Zendesk said the emails were ticket creation notifications from customer accounts that configured their Zendesk instance to allow anyone to submit support requests — including anonymous users.

“These types of support tickets can be part of a customer’s workflow, where a prior verification is not required to allow them to engage and make use of the Support capabilities,” said Carolyn Camoens, communications director at Zendesk. “Although we recommend our customers to permit only verified users to submit tickets, some Zendesk customers prefer to use an anonymous environment to allow for tickets to be created due to various business reasons.”

Camoens said requests that can be submitted in an anonymous manner can also make use of an email address of the submitter’s choice.

“However, this method can also be used for spam requests to be created on behalf of third party email addresses,” Camoens said. “If an account has enabled the auto-responder trigger based on ticket creation, then this allows for the ticket notification email to be sent from our customer’s accounts to these third parties. The notification will also include the Subject added by the creator of these tickets.”

Zendesk claims it uses rate limits to prevent a high volume of requests from being created at once, but those limits did not stop Zendesk customers from flooding my inbox with thousands of messages in just a few hours.

“We recognize that our systems were leveraged against you in a distributed, many-against-one manner,” Camoens said. “We are actively investigating additional preventive measures. We are also advising customers experiencing this type of activity to follow our general security best practices and configure an authenticated ticket creation workflow.”

In all of the cases above, the messaging abuse would not have been possible if Zendesk customers validated support request email addresses prior to sending responses. Failing to do so may make it easier for Zendesk clients to handle customer support requests, but it also allows ne’er-do-wells to sully the sender’s brand in service of disruptive and malicious email floods.

Patch Tuesday, October 2025 ‘End of 10’ Edition

October 14, 2025

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Microsoft today released software updates to plug a whopping 172 security holes in its Windows operating systems, including at least two vulnerabilities that are already being actively exploited. October’s Patch Tuesday also marks the final month that Microsoft will ship security updates for Windows 10 systems. If you’re running a Windows 10 PC and you’re unable or unwilling to migrate to Windows 11, read on for other options.

The first zero-day bug addressed this month (CVE-2025-24990) involves a third-party modem driver called Agere Modem that’s been bundled with Windows for the past two decades. Microsoft responded to active attacks on this flaw by completely removing the vulnerable driver from Windows.

The other zero-day is CVE-2025-59230, an elevation of privilege vulnerability in Windows Remote Access Connection Manager (also known as RasMan), a service used to manage remote network connections through virtual private networks (VPNs) and dial-up networks.

“While RasMan is a frequent flyer on Patch Tuesday, appearing more than 20 times since January 2022, this is the first time we’ve seen it exploited in the wild as a zero day,” said Satnam Narang, senior staff research engineer at Tenable.

Narang notes that Microsoft Office users should also take note of CVE-2025-59227 and CVE-2025-59234, a pair of remote code execution bugs that take advantage of “Preview Pane,” meaning that the target doesn’t even need to open the file for exploitation to occur. To execute these flaws, an attacker would social engineer a target into previewing an email with a malicious Microsoft Office document.

Speaking of Office, Microsoft quietly announced this week that Microsoft Word will now automatically save documents to OneDrive, Microsoft’s cloud platform. Users who are uncomfortable saving all of their documents to Microsoft’s cloud can change this in Word’s settings; ZDNet has a useful how-to on disabling this feature.

Kev Breen, senior director of threat research at Immersive, called attention to CVE-2025-59287, a critical remote code execution bug in the Windows Server Update Service (WSUS) — the very same Windows service responsible for downloading security patches for Windows Server versions. Microsoft says there are no signs this weakness is being exploited yet. But with a threat score of 9.8 out of possible 10 and marked “exploitation more likely,” CVE-2025-59287 can be exploited without authentication and is an easy “patch now” candidate.

“Microsoft provides limited information, stating that an unauthenticated attacker with network access can send untrusted data to the WSUS server, resulting in deserialization and code execution,” Breen wrote. “As WSUS is a trusted Windows service that is designed to update privileged files across the file system, an attacker would have free rein over the operating system and could potentially bypass some EDR detections that ignore or exclude the WSUS service.”

For more on other fixes from Redmond today, check out the SANS Internet Storm Center monthly roundup, which indexes all of the updates by severity and urgency.

Windows 10 isn’t the only Microsoft OS that is reaching end-of-life today; Exchange Server 2016, Exchange Server 2019, Skype for Business 2016, Windows 11 IoT Enterprise Version 22H2, and Outlook 2016 are some of the other products that Microsoft is sunsetting today.

If you’re running any Windows 10 systems, you’ve probably already determined whether your PC meets the technical hardware specs recommended for the Windows 11 OS. If you’re reluctant or unable to migrate a Windows 10 system to Windows 11, there are alternatives to simply continuing to use Windows 10 without ongoing security updates. Continue reading →

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