propublica.org - Microsoft announced that Chinese state-sponsored hackers had exploited vulnerabilities in its popular SharePoint software but didn’t mention that it has long used China-based engineers to maintain the product.
ast month, Microsoft announced that Chinese state-sponsored hackers had exploited vulnerabilities in SharePoint, the company’s widely used collaboration software, to access the computer systems of hundreds of companies and government agencies, including the National Nuclear Security Administration and the Department of Homeland Security.

The company did not include in its announcement, however, that support for SharePoint is handled by a China-based engineering team that has been responsible for maintaining the software for years.

ProPublica viewed screenshots of Microsoft’s internal work-tracking system that showed China-based employees recently fixing bugs for SharePoint “OnPrem,” the version of the software involved in last month’s attacks. The term, short for “on premises,” refers to software installed and run on customers’ own computers and servers.

Microsoft said the China-based team “is supervised by a US-based engineer and subject to all security requirements and manager code review. Work is already underway to shift this work to another location.”

It’s unclear if Microsoft’s China-based staff had any role in the SharePoint hack. But experts have said allowing China-based personnel to perform technical support and maintenance on U.S. government systems can pose major security risks. Laws in China grant the country’s officials broad authority to collect data, and experts say it is difficult for any Chinese citizen or company to meaningfully resist a direct request from security forces or law enforcement. The Office of the Director of National Intelligence has deemed China the “most active and persistent cyber threat to U.S. Government, private-sector, and critical infrastructure networks.”

ProPublica revealed in a story published last month that Microsoft has for a decade relied on foreign workers — including those based in China — to maintain the Defense Department’s cloud systems, with oversight coming from U.S.-based personnel known as digital escorts. But those escorts often don’t have the advanced technical expertise to police foreign counterparts with far more advanced skills, leaving highly sensitive information vulnerable, the investigation showed.

ProPublica found that Microsoft developed the escort arrangement to satisfy Defense Department officials who were concerned about the company’s foreign employees, and to meet the department’s requirement that people handling sensitive data be U.S. citizens or permanent residents. Microsoft went on to win federal cloud computing business and has said in earnings reports that it receives “substantial revenue from government contracts.” ProPublica also found that Microsoft uses its China-based engineers to maintain the cloud systems of other federal departments, including parts of Justice, Treasury and Commerce.

In response to the reporting, Microsoft said that it had halted its use of China-based engineers to support Defense Department cloud computing systems, and that it was considering the same change for other government cloud customers. Additionally, Defense Secretary Pete Hegseth launched a review of tech companies’ reliance on foreign-based engineers to support the department. Sens. Tom Cotton, an Arkansas Republican, and Jeanne Shaheen, a New Hampshire Democrat, have written letters to Hegseth, citing ProPublica’s investigation, to demand more information about Microsoft’s China-based support.

Microsoft said its analysis showed that Chinese hackers were exploiting SharePoint weaknesses as early as July 7. The company released a patch on July 8, but hackers were able to bypass it. Microsoft subsequently issued a new patch with “more robust protections.”

The U.S. Cybersecurity and Infrastructure Security Agency said that the vulnerabilities enable hackers “to fully access SharePoint content, including file systems and internal configurations, and execute code over the network.” Hackers have also leveraged their access to spread ransomware, which encrypts victims’ files and demands a payment for their release, CISA said.

reuters.com - July 30 (Reuters) - More than 90 state and local governments have been targeted using the recently revealed vulnerability in Microsoft server software, according to a U.S. group devoted to helping local authorities collaborate against hacking threats.
The nonprofit Center for Internet Security, which houses an information-sharing group for state, local, tribal, and territorial government entities, provided no further details about the targets, but said it did not have evidence that the hackers had broken through.

None have resulted in confirmed security incidents," Randy Rose, the center's vice president of security operations and intelligence, said in an email.
A wave of hacks hit servers running vulnerable versions of Microsoft SharePoint this month, causing widespread concern. The campaign has claimed at least 400 victims, according to Netherlands-based cybersecurity firm Eye Security. Multiple federal government agencies are reportedly among the victims, and new ones are being identified every day.
On Wednesday, a spokesperson for one of the U.S. Department of Energy's 17 national labs said it was among those hit.

"Attackers did attempt to access Fermilab's SharePoint servers," the spokesperson said, referring to the U.S. Fermi National Accelerator Laboratory. "The attackers were quickly identified, and the impact was minimal, with no sensitive or classified data accessed." The Fermilab incident was first reported by Bloomberg.
The U.S. Department of Energy has previously said the SharePoint security hack has affected "a very small number" of its systems

theregister.com - A week after Microsoft told the world that its July software updates didn't fully fix a couple of bugs, which allowed miscreants to take over on-premises SharePoint servers and remotely execute code, researchers have assembled much of the puzzle — with one big missing piece.

How did the attackers, who include Chinese government spies, data thieves, and ransomware operators, know how to exploit the SharePoint CVEs in such a way that would bypass the security fixes Microsoft released the following day?

"A leak happened here somewhere," Dustin Childs, head of threat awareness at Trend Micro's Zero Day Initiative (ZDI), told The Register. "And now you've got a zero-day exploit in the wild, and worse than that, you've got a zero-day exploit in the wild that bypasses the patch, which came out the next day."

Countdown to mass exploitation
It all began back in May, on stage at the Pwn2Own competition.

Pwn2Own is the hackers' equivalent of the World Series, and ZDI usually hosts these competitions twice a year.

The most recent contest occurred in Berlin, beginning May 15. On day 2 of the event, Vietnamese researcher Dinh Ho Anh Khoa combined an auth bypass and an insecure deserialization bug to exploit Microsoft SharePoint and win $100,000.

"What happens on the stage is just one part of Pwn2Own," Childs said.

After demonstrating a successful exploit, the bug hunter and vendor are whisked away into a private room where the researcher explains what they did and provides the technology company with a full write-up of the exploit. Assuming it's not a duplicate or already known vulnerability, the vendor then has 90 days to issue a fix before the bug and exploit are made public.

"So Microsoft received the working exploit in a white paper describing everything on that day," Childs said.

Less than two months later, on July 8, the software giant disclosed the two CVEs – CVE-2025-49704, which allows unauthenticated remote code execution, and CVE-2025-49706, a spoofing bug – and released software updates intended to patch the flaws. But mass exploitation had already started the day before, on July 7.

"Sixty days to fix really isn't a bad timeline for a bug that stays private and stays under coordinated disclosure rules," Childs said. "What is bad: a leak happened."

There's another key date that may shed light on when that leak happened.

Patch Tuesday happens the second Tuesday of every month – in July, that was the 8th. But two weeks before then, Microsoft provides early access to some security vendors via the Microsoft Active Protections Program (MAPP).

These vendors are required to sign a non-disclosure agreement about the soon-to-be-disclosed bugs, and Microsoft gives them early access to the vulnerability information so that they can provide updated protections to customers faster.

"The first MAPP drop occurs at what we call r minus 14, which is two weeks ahead of the [Patch Tuesday] release," Childs said – that is, beginning on June 24. "Then, on July 7, we started to see attacks. July 8, the patches were out and were almost immediately bypassed."

ZDI, along with other security providers, poked holes in the initial patches and determined that the authentication bypass piece was too narrow, and attackers could easily bypass this fix. In fact, anyone who received the early MAPP information about the CVEs and software updates "would be able to tell that this is an easy way to get past it," Childs said.

On July 18, Eye Security first sounded the alarm on "large-scale exploitation of a new SharePoint remote code execution (RCE) vulnerability chain in the wild."

A day later, Microsoft warned SharePoint server users that three on-prem versions of the product included a zero-day flaw that was under attack – and that its own failure to completely patch the holes was to blame.

By July 21, Redmond had issued software updates for all three versions. But by then, more than 400 organizations had been compromised by at least two Chinese state-sponsored crews, Linen Typhoon and Violet Typhoon, plus a gang Microsoft tracks as Storm-2603, which was abusing the vulnerabilities to deploy ransomware.

Microsoft declined to answer The Register's specific questions for this story. "As part of our standard process, we'll review this incident, find areas to improve, and apply those improvements broadly," a Microsoft spokesperson said in an emailed statement.

One researcher suggests a leak may not have been the only pathway to exploit. "Soroush Dalili was able to use Google's Gemini to help reproduce the exploit chain, so it's possible the threat actors did their own due diligence, or did something similar to Dalili, working with one of the frontier large language models like Google Gemini, o3 from OpenAI, or Claude Opus, or some other LLM, to help identify routes of exploitation," Tenable Research Special Operations team senior engineer Satnam Narang told The Register.

"It's difficult to say what domino had to fall in order for these threat actors to be able to leverage these flaws in the wild," Narang added.

microsoft.com - July 23, 2025 update – Expanded analysis and threat intelligence from our continued monitoring of exploitation activity by Storm-2603 leading to the deployment of Warlock ransomware. Based on new information, we have updated the Attribution, Indicators of compromise, extended and clarified Mitigation and protection guidance (including raising Step 6: Restart IIS for emphasis), Detections, and Hunting sections.

On July 19, 2025, Microsoft Security Response Center (MSRC) published a blog addressing active attacks against on-premises SharePoint servers that exploit CVE-2025-49706, a spoofing vulnerability, and CVE-2025-49704, a remote code execution vulnerability. These vulnerabilities affect on-premises SharePoint servers only and do not affect SharePoint Online in Microsoft 365. Microsoft has released new comprehensive security updates for all supported versions of SharePoint Server (Subscription Edition, 2019, and 2016) that protect customers against these new vulnerabilities. Customers should apply these updates immediately to ensure they are protected.

These comprehensive security updates address newly disclosed security vulnerabilities in CVE-2025-53770 that are related to the previously disclosed vulnerability CVE-2025-49704. The updates also address the security bypass vulnerability CVE-2025-53771 for the previously disclosed CVE-2025-49706.

As of this writing, Microsoft has observed two named Chinese nation-state actors, Linen Typhoon and Violet Typhoon exploiting these vulnerabilities targeting internet-facing SharePoint servers. In addition, we have observed another China-based threat actor, tracked as Storm-2603, exploiting these vulnerabilities to deploy ransomware. Investigations into other actors also using these exploits are still ongoing. With the rapid adoption of these exploits, Microsoft assesses with high confidence that threat actors will continue to integrate them into their attacks against unpatched on-premises SharePoint systems. This blog shares details of observed exploitation of CVE-2025-49706 and CVE-2025-49704 and the follow-on tactics, techniques, and procedures (TTPs) by threat actors. We will update this blog with more information as our investigation continues.

Microsoft recommends customers to use supported versions of on-premises SharePoint servers with the latest security updates. To stop unauthenticated attacks from exploiting this vulnerability, customers should also integrate and enable Antimalware Scan Interface (AMSI) and Microsoft Defender Antivirus (or equivalent solutions) for all on-premises SharePoint deployments and configure AMSI to enable Full Mode as detailed in Mitigations section below. Customers should also rotate SharePoint server ASP.NET machine keys, restart Internet Information Services (IIS), and deploy Microsoft Defender for Endpoint or equivalent solutions.

Unknown threat actors have breached the National Nuclear Security Administration's network in attacks exploiting a recently patched Microsoft SharePoint zero-day vulnerability chain.

NNSA is a semi-autonomous U.S. government agency part of the Energy Department that maintains the country's nuclear weapons stockpile and is also tasked with responding to nuclear and radiological emergencies within the United States and abroad.

A Department of Energy spokesperson confirmed in a statement that hackers gained access to NNSA networks last week.

"On Friday, July 18th, the exploitation of a Microsoft SharePoint zero-day vulnerability began affecting the Department of Energy, including the NNSA," Department of Energy Press Secretary Ben Dietderich told BleepingComputer. "The Department was minimally impacted due to its widespread use of the Microsoft M365 cloud and very capable cybersecurity systems."

Dietderich added that only "a very small number of systems were impacted" and that "all impacted systems are being restored."

As first reported by Bloomberg, sources within the agency also noted that there's no evidence of sensitive or classified information compromised in the breach.

The APT29 Russian state-sponsored threat group, the hacking division of the Russian Foreign Intelligence Service (SVR), also breached the U.S. nuclear weapons agency in 2019 using a trojanized SolarWinds Orion update.
Attacks linked to Chinese state hackers, over 400 servers breached
On Tuesday, Microsoft and Google linked the widespread attacks targeting a Microsoft SharePoint zero-day vulnerability chain (known as ToolShell) to Chinese state-sponsored hacking groups.

"Microsoft has observed two named Chinese nation-state actors, Linen Typhoon and Violet Typhoon exploiting these vulnerabilities targeting internet-facing SharePoint servers," Microsoft said.

"In addition, we have observed another China-based threat actor, tracked as Storm-2603, exploiting these vulnerabilities. Investigations into other actors also using these exploits are still ongoing."

Dutch cybersecurity firm Eye Security first detected the zero-day attacks on Friday, stating that at least 54 organizations had already been compromised, including national government entities and multinational companies.

Cybersecurity firm Check Point later revealed that it had spotted signs of exploitation going back to July 7th targeting dozens of government, telecommunications, and technology organizations in North America and Western Europe.

Weekend attacks compromised about 100 organisations
May hacker contest uncovered SharePoint weak spot
Initial Microsoft patch did not fully fix flaw

LONDON, July 22 (Reuters) - A security patch Microsoft (MSFT.O), opens new tab released this month failed to fully fix a critical flaw in the U.S. tech giant's SharePoint server software, opening the door to a sweeping global cyber espionage effort, a timeline reviewed by Reuters shows.
On Tuesday, a Microsoft spokesperson confirmed that its initial solution to the flaw, identified at a hacker competition in May, did not work, but added that it released further patches that resolved the issue.
It remains unclear who is behind the spy effort, which targeted about 100 organisations over the weekend, and is expected to spread as other hackers join the fray.
In a blog post Microsoft said two allegedly Chinese hacking groups, dubbed "Linen Typhoon" and "Violet Typhoon," were exploiting the weaknesses, along with a third, also based in China.
Microsoft and Alphabet's (GOOGL.O), opens new tab Google have said China-linked hackers were probably behind the first wave of hacks.
Chinese government-linked operatives are regularly implicated in cyberattacks, but Beijing routinely denies such hacking operations.
In an emailed statement, its embassy in Washington said China opposed all forms of cyberattacks, and "smearing others without solid evidence."

The vulnerability opening the way for the attack was first identified in May at a Berlin hacking competition, opens new tab organised by cybersecurity firm Trend Micro (4704.T), opens new tab that offered cash bounties for finding computer bugs in popular software.
It offered a $100,000 prize for so-called "zero-day" exploits that leverage previously undisclosed digital weaknesses that could be used against SharePoint, Microsoft's flagship document management and collaboration platform.
The U.S. National Nuclear Security Administration, charged with maintaining and designing the nation's cache of nuclear weapons, was among the agencies breached, Bloomberg News said on Tuesday, citing a person with knowledge of the matter.

krebsonsecurity.com - On Sunday, July 20, Microsoft Corp. issued an emergency security update for a vulnerability in SharePoint Server that is actively being exploited to compromise vulnerable organizations. The patch comes amid reports that malicious hackers have used the SharePoint flaw to breach U.S. federal and state agencies, universities, and energy companies.
In an advisory about the SharePoint security hole, a.k.a. CVE-2025-53770, Microsoft said it is aware of active attacks targeting on-premises SharePoint Server customers and exploiting vulnerabilities that were only partially addressed by the July 8, 2025 security update.

The Cybersecurity & Infrastructure Security Agency (CISA) concurred, saying CVE-2025-53770 is a variant on a flaw Microsoft patched earlier this month (CVE-2025-49706). Microsoft notes the weakness applies only to SharePoint Servers that organizations use in-house, and that SharePoint Online and Microsoft 365 are not affected.

The Washington Post reported on Sunday that the U.S. government and partners in Canada and Australia are investigating the hack of SharePoint servers, which provide a platform for sharing and managing documents. The Post reports at least two U.S. federal agencies have seen their servers breached via the SharePoint vulnerability.

According to CISA, attackers exploiting the newly-discovered flaw are retrofitting compromised servers with a backdoor dubbed “ToolShell” that provides unauthenticated, remote access to systems. CISA said ToolShell enables attackers to fully access SharePoint content — including file systems and internal configurations — and execute code over the network.

Researchers at Eye Security said they first spotted large-scale exploitation of the SharePoint flaw on July 18, 2025, and soon found dozens of separate servers compromised by the bug and infected with ToolShell. In a blog post, the researchers said the attacks sought to steal SharePoint server ASP.NET machine keys.

“These keys can be used to facilitate further attacks, even at a later date,” Eye Security warned. “It is critical that affected servers rotate SharePoint server ASP.NET machine keys and restart IIS on all SharePoint servers. Patching alone is not enough. We strongly advise defenders not to wait for a vendor fix before taking action. This threat is already operational and spreading rapidly.”

Microsoft’s advisory says the company has issued updates for SharePoint Server Subscription Edition and SharePoint Server 2019, but that it is still working on updates for supported versions of SharePoint 2019 and SharePoint 2016.

CISA advises vulnerable organizations to enable the anti-malware scan interface (AMSI) in SharePoint, to deploy Microsoft Defender AV on all SharePoint servers, and to disconnect affected products from the public-facing Internet until an official patch is available.

The security firm Rapid7 notes that Microsoft has described CVE-2025-53770 as related to a previous vulnerability — CVE-2025-49704, patched earlier this month — and that CVE-2025-49704 was part of an exploit chain demonstrated at the Pwn2Own hacking competition in May 2025. That exploit chain invoked a second SharePoint weakness — CVE-2025-49706 — which Microsoft unsuccessfully tried to fix in this month’s Patch Tuesday.

Microsoft also has issued a patch for a related SharePoint vulnerability — CVE-2025-53771; Microsoft says there are no signs of active attacks on CVE-2025-53771, and that the patch is to provide more robust protections than the update for CVE-2025-49706.

This is a rapidly developing story. Any updates will be noted with timestamps.

forbes.com - Microsoft has confirmed that SharePoint Server is under mass attack and no patch is yet available — here’s what you need to know and how to mitigate the threat.

Microsoft Confirms CVE-2025-53770 SharePoint Server Attacks
It’s been quite the few weeks for security warnings, what with Amazon informing 220 million customers of Prime account attacks, and claims of a mass hack of Ring doorbells going viral. The first of those can be mitigated by basic security hygiene, and the latter appears to be a false alarm. The same cannot be said for CVE-2025-53770, a newly uncovered and confirmed attack against users of SharePoint Server which is currently undergoing mass exploitation on a global level, according to the Eye Research experts who discovered it. Microsoft, meanwhile, has admitted that not only is it “aware of active attacks” but, worryingly, “a patch is currently not available for this vulnerability.”

CVE-2025-53770, which is also being called ToolShell, is a critical vulnerability in on-premises SharePoint. The end result of which is the ability for attackers to gain access and control of said servers without authentication. If that sounds bad, it’s because it is. Very bad indeed.

“The risk is not theoretical,” the researchers warned, “attackers can execute code remotely, bypassing identity protections such as MFA or SSO.” Once they have, they can then “access all SharePoint content, system files, and configurations and move laterally across the Windows Domain.”

And then there’s the theft of cryptographic keys. That can enable an attacker to “impersonate users or services,” according to the report, “even after the server is patched.” So, even when a patch is eventually released, and I would expect an emergency update to arrive fairly quickly for this one, the problem isn’t solved. You will, it was explained, “need to rotate the secrets allowing all future tokens that can be created by the malicious actor to become invalid.”

And, of course, as SharePoint will often connect to other core services, including the likes of Outlook and Teams, oh and not forgetting OneDrive, the threat, if exploited, can and will lead to “data theft, password harvesting, and lateral movement across the network,” the researchers warned.

During the second day of Pwn2Own Berlin 2025, competitors earned $435,000 after exploiting zero-day bugs in multiple products, including Microsoft SharePoint, VMware ESXi, Oracle VirtualBox, Red Hat Enterprise Linux, and Mozilla Firefox.
The highlight was a successful attempt from Nguyen Hoang Thach of STARLabs SG against the VMware ESXi, which earned him $150,000 for an integer overflow exploit.

Dinh Ho Anh Khoa of Viettel Cyber Security was awarded $100,000 for hacking Microsoft SharePoint by leveraging an exploit chain combining an auth bypass and an insecure deserialization flaw.

Palo Alto Networks' Edouard Bochin and Tao Yan also demoed an out-of-bounds write zero-day in Mozilla Firefox, while Gerrard Tai of STAR Labs SG escalated privileges to root on Red Hat Enterprise Linux using a use-after-free bug, and Viettel Cyber Security used another out-of-bounds write for an Oracle VirtualBox guest-to-host escape.

In the AI category, Wiz Research security researchers used a use-after-free zero-day to exploit Redis and Qrious Secure chained four security flaws to hack Nvidia's Triton Inference Server.

On the first day, competitors were awarded $260,000 after successfully exploiting zero-day vulnerabilities in Windows 11, Red Hat Linux, and Oracle VirtualBox, reaching a total of $695,000 earned over the first two days of the contest after demonstrating 20 unique 0-days.

​​​The Pwn2Own Berlin 2025 hacking competition focuses on enterprise technologies, introduces an AI category for the first time, and takes place during the OffensiveCon conference between May 15 and May 17.

ForitGuard Lab reveals a modified Havoc deployed by a ClickFix phishing campaign. The threat actor hides each stage behind SharePoint and also uses it as a C2.

Since mid-April 2024, Microsoft has observed an increase in defense evasion tactics used in campaigns abusing file hosting services like SharePoint, OneDrive, and Dropbox. These campaigns use sophisticated techniques to perform social engineering, evade detection, and compromise identities, and include business email compromise (BEC) attacks.

Yes, the title is right. This blog covers an XML eXternal Entity (XXE) injection vulnerability that I found in SharePoint. The bug was recently patched by Microsoft. In general, XXE vulnerabilities are not very exciting in terms of discovery and related technical aspects. They may sometimes be fun t

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added a critical security vulnerability impacting Microsoft SharePoint Server to its

Brief I may have achieved successful exploitation of a SharePoint target during Pwn2Own Vancouver 2023. While the live demonstration lasted only approximately 30 seconds, it is noteworthy that the process of discovering and crafting the exploit chain consumed nearly a year of meticulous effort and research to complete the full exploit chain.
This exploit chain leverages two vulnerabilities to achieve pre-auth remote code execution (RCE) on the SharePoint server:
Authentication Bypass – An unauthenticated attacker can impersonate as any SharePoint user by spoofing valid JSON Web Tokens (JWTs), using the none signing algorithm to subvert signature validation checks when verifying JWT tokens used for OAuth authentication.