CVE-2022-41040 and CVE-2022-41082: ProxyShell Variant Exploited in the Wild
Microsoft has confirmed reports of two zero-day vulnerabilities in Microsoft Exchange Server that have been exploited in the wild. Patches are not yet available.
Update November 9: Microsoft has released patches for CVE-2022-41040 and CVE-2022-41082 and updated its advisories.
Background
On September 28, GTSC Cybersecurity Technology Company Limited published a blog post (English translation published later) regarding their discovery of two zero-day vulnerabilities in Microsoft Exchange Server. According to GTSC, its Security Operations Center team discovered the exploitation in August 2022 during its “security monitoring & incident response services.”
GTSC reported these vulnerabilities through Trend Micro’s Zero Day Initiative (ZDI) but, seeing more evidence of exploitation against other targets, decided to publish information about the flaws along with indicators of compromise and mitigation guidance to help organizations defend against attacks.
Late on September 29, Microsoft confirmed the vulnerabilities and assigned CVEs — CVE-2022-41040 and CVE-2022-41082 — but has yet to release patches, stating “we are working on an accelerated timeline to release a fix.” On September 30, Microsoft published an additional blog post with further mitigation instructions and, on October 3, it published advisory pages for both flaws.
Analysis
CVE-2022-41040 is an authenticated server-side request forgery vulnerability in Microsoft Exchange Servers that was assigned a CVSSv3 score of 6.3 by ZDI. Exploitation of CVE-2022-41040 could allow an attacker to exploit CVE-2022-41082.
CVE-2022-41082 is an authenticated remote code execution vulnerability assigned a CVSSv3 score of 8.8. It is very similar to ProxyShell, a chain of three vulnerabilities in Exchange Server discovered by Orange Tsai in 2021. However, the original ProxyShell attack chain did not require authentication, while CVE-2022-41082 does.
Looks like a neat variant!
— Orange Tsai 🍊 (@orange_8361) September 29, 2022
Proof of concept
The team at GTSC provided details of the post-exploitation activity it observed in attacks exploiting these vulnerabilities, but were careful not to publish a detailed proof-of-concept (PoC). No public PoC has been identified yet.
Vendor response
On November 8, Microsoft released patches for both vulnerabilities as part of Patch Tuesday.
On September 29, Microsoft released a blog post with information on detection and mitigation for these vulnerabilities that it later updated to improve the mitigation guidance in response to testing by security researchers that proved the original mitigations could be bypassed. Organizations are strongly urged to apply the patches, now that they are available.
Identifying affected systems
A list of Tenable plugins to identify these vulnerabilities will appear here as they’re released. This link uses a search filter to ensure that all matching plugin coverage will appear as it is released. When patches are released by Microsoft, additional plugins will be released to identify impacted systems.
While additional plugin coverage is being investigated, we do recommend utilizing the following plugins to identify Microsoft Exchange hosts in your environment:
- Plugin ID 108804 - Microsoft Exchange Server Detection (Uncredentialed)
- Plugin ID 77910 - Microsoft Exchange Installed
In addition, Tenable has released a new plugin (Plugin ID 165705) which will report all currently supported versions of Microsoft Exchange with a High severity rating. This will aid our customers in identifying systems with Microsoft Exchange installed that are currently affected by the unpatched zero-day vulnerabilities. This plugin is available as of Nessus Plugin Feed Serial ID 202210060050.
Get more information
- Microsoft Blog Post: Customer Guidance for Reported Zero-day Vulnerabilities in Microsoft Exchange Server
- Microsoft Blog Post: Analyzing attacks using the Exchange vulnerabilities CVE-2022-41040 and CVE-2022-41082
- GTSC Cybersecurity Technology Company Limited’s Write Up (English Language)
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Change Log
Update November 9: Microsoft has released patches for CVE-2022-41040 and CVE-2022-41082 and updated its advisories.
Update October 6: The Identifying affected systems section has been updated to reflect a new plugin release.
Update October 5: The Vendor Response section has been updated to reflect new mitigation guidance from Microsoft.
Update October 4:The Identifying affected systems section has been updated with additional guidance.
Update October 3: The Background and Vendor Response sections have been updated based on new blog posts and advisories from Microsoft.
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