High
CVE-2021-31979
CVE-2021-31979
Description
Windows Kernel Elevation of Privilege Vulnerability This CVE ID is unique from CVE-2021-33771, CVE-2021-34514.
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Technical Analysis
Update: Looks like this was used by the exploit brokerage company Candiru along with CVE-2021-33771 to deliver spyware to targeted users, which according to Microsoft’s blog post, affected at least 100 victims in Palestine, Israel, Iran, Lebanon, Yemen, Spain, United Kingdom, Turkey, Armenia, and Singapore. Victims include human rights defenders, dissidents, journalists, activists, and politicians.
Hmm, this is a particularly juicy bug as it seems to affect all Windows systems from Windows 7 up to the latest Windows 10. This is in contrast to CVE-2021-33771, which only affects Windows 8.1 and later. Both bugs affect the Windows Kernel and are being actively exploited in the wild for LPE.
There is little information on what actually is the issue here, although https://twitter.com/mavillon1/status/1415149124064878593/ suggests that MiFlashDataSecton, EtwpUpdatePeriodicCaptureState and AlpcpProcessSynchronousRequest may be possible culprits and reviewing AlpcpProcessSynchronousRequest shows that a potential integer overflow was fixed.
Given that Microsoft also lists the attack complexity for both vulnerabilities as Low it seems likely that other researchers will find a way to replicate these vulnerabilities and create working PoCs for them, particularly given that they have been exploited in the wild. Based on this evidence, it is highly recommended to patch these issues as soon as possible.
Further updates will be made to this post if and when these CVEs are tied to specific vulnerable functions.
CVSS V3 Severity and Metrics
General Information
Vendors
- Microsoft
Products
- Windows,
- Windows Server,
- Windows 10 Version 1909 for 32-bit Systems,
- Windows 10 Version 1909 for x64-based Systems,
- Windows 10 Version 1909 for ARM64-based Systems,
- Windows 10 Version 21H1 for x64-based Systems,
- Windows 10 Version 21H1 for ARM64-based Systems,
- Windows 10 Version 21H1 for 32-bit Systems,
- Windows 10 Version 2004 for 32-bit Systems,
- Windows 10 Version 2004 for ARM64-based Systems,
- Windows 10 Version 2004 for x64-based Systems,
- Windows Server, version 2004 (Server Core installation),
- Windows 10 Version 20H2 for x64-based Systems,
- Windows 10 Version 20H2 for 32-bit Systems,
- Windows 10 Version 20H2 for ARM64-based Systems,
- Windows Server, version 20H2 (Server Core Installation)
Exploited in the Wild
