Watch Out! Researchers Spot New Microsoft Office Zero
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2021-40444 | Remote Code Execution via MSHTML Rendering Engine in Microsoft Windows/Office (CVE-2021-40444) CVE-2021-40444 is a remote code execution vulnerability in the Microsoft MSHTML browser rendering engine, which Microsoft Office documents can load on Windows systems. It is triggered when a user is convinced to open a specially crafted Office document containing a malicious ActiveX control hosted by the MSHTML engine (tracked as a path-traversal-class issue, CWE-22). A successful attacker gains the ability to run arbitrary code in the context of the logged-on user, with greater impact when that user has administrative rights. Any Windows system that can open Office documents is exposed, spanning Windows 7, 8.1, RT 8.1, Windows 10 (1507 through 21H1) and Windows Server 2004/2008. Exploitation is confirmed in the wild: Microsoft observed targeted attacks at disclosure, the flaw is in CISA's KEV with known ransomware use, and Microsoft released security updates on September 14, 2021. Do: Apply Microsoft's security updates released September 14, 2021 for your Windows version immediately; this is a CISA KEV item with known ransomware use, so patching is treated as mandatory. As interim protection, keep Microsoft Defender Antivirus/Defender for Endpoint signatures current (enterprise detection build 1.349.22.0 or newer, with alerts appearing as 'Suspicious Cpl File Execution') and avoid opening untrusted Office documents, since exploitation requires user interaction with a crafted file. | 8.8 | 97% | KEV ransomware PoC ×2 |
| masshundreds of millions of Windows PCs and servers (nearly all Windows desktop/laptop installs on affected versions at disclosure) |
Indicators of compromiseauto-extracted · verify before use · export allAll →
| Type | Indicator | Context |
|---|---|---|
| domain | xmlformats.com | the exploit originated from a now-unreachable domain named "xmlformats[.]com." "A Rich Text Format file (.RTF) could trigger the invoc |
Full article449 words · extracted from thehackernews.com · click to collapse
Ravie LakshmananMay 30, 2022
Cybersecurity researchers are calling attention to a zero-day flaw in Microsoft Office that could be abused to achieve arbitrary code execution on affected Windows systems.
The vulnerability came to light after an independent cybersecurity research team known as nao_sec uncovered a Word document ("05-2022-0438.doc") that was uploaded to VirusTotal from an IP address in Belarus.
"It uses Word's external link to load the HTML and then uses the 'ms-msdt' scheme to execute PowerShell code," the researchers noted in a series of tweets last week.
According to security researcher Kevin Beaumont, who dubbed the flaw "Follina," the maldoc leverages Word's remote template feature to fetch an HTML file from a server, which then makes use of the "ms-msdt://" URI scheme to run the malicious payload.
The shortcoming has been so named because the malicious sample references 0438, which is the area code of Follina, a municipality in the Italian city of Treviso.
MSDT is short for Microsoft Support Diagnostics Tool, a utility that's used to troubleshoot and collect diagnostic data for analysis by support professionals to resolve a problem.
"There's a lot going on here, but the first problem is Microsoft Word is executing the code via msdt (a support tool) even if macros are disabled," Beaumont explained.
"Protected View does kick in, although if you change the document to RTF form, it runs without even opening the document (via the preview tab in Explorer) let alone Protected View," the researcher added.
In a standalone analysis, cybersecurity company Huntress Labs detailed the attack flow, noting the HTML file ("RDF842l.html") that triggers the exploit originated from a now-unreachable domain named "xmlformats[.]com."
"A Rich Text Format file (.RTF) could trigger the invocation of this exploit with just the Preview Pane within Windows Explorer," Huntress Labs' John Hammond said. "Much like CVE-2021-40444, this extends the severity of this threat by not just 'single-click' to exploit, but potentially with a 'zero-click' trigger."
Multiple Microsoft Office versions, including Office, Office 2016, and Office 2021, are said to be affected, although other versions are expected to be vulnerable as well.
What's more, Richard Warren of NCC Group managed to demonstrate an exploit on Office Professional Pro with April 2022 patches running on an up-to-date Windows 11 machine with the preview pane enabled.
"Microsoft are going to need to patch it across all the different product offerings, and security vendors will need robust detection and blocking," Beaumont said. We have reached out to Microsoft for comment, and we'll update the story once we hear back.
Found this article interesting? Follow us on Google News, Twitter and LinkedIn to read more exclusive content we post.
Text extracted automatically; images, tables and formatting may be missing. Original: https://thehackernews.com/2022/05/watch-out-researchers-spot-new.html