Moderate
CVE-2021-24088
CVE-2021-24088
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Technical Analysis
This entry is based off the blackhat talk by Zhiniang Peng, Xuefeng Li, and Lewis Lee on August 4, 2021.
They said CVE-2021-24088, 24077, and 1722 were all similar, but only described 24088.
For 24088, there’s a bug in EnumJobsInLocalQueue where the user submits a buffer and job size. Because the buffer used in this case has metadata written to the top of the buffer and strings written to the bottom of the buffer, the buffer functionally grows toward the middle (AKA itself). There bug is in the check to ensure proper size of the buffer so that it does not cause an overwrite of the string data to the metadata, but that check is vulnerable to an integer overflow (I am not sure of the exact cause). Because the check can be bypassed using the integer overflow, it means someone can arbitrarily write data in the form of a string to the meta data section, or even underflow the address and write arbitrary data to adjacent heap allocations.
Because the nature of the exploit, being able to write arbitrary data to the heap could result in code execution, but as I have not seen a PoC that goes through all the steps, I’m unable to say definitively how easy the exploit is to create or run or what the attacker value is. Mitigations are as always, patch, and/or disable the spooler service on devices that do not need it.
CVSS V3 Severity and Metrics
General Information
Vendors
- microsoft
Products
- windows 10 -,
- windows 10 1607,
- windows 10 1803,
- windows 10 1809,
- windows 10 1909,
- windows 10 2004,
- windows 10 20h2,
- windows 7 -,
- windows 8.1 -,
- windows rt 8.1 -,
- windows server 2008 -,
- windows server 2008 r2,
- windows server 2012 -,
- windows server 2012 r2,
- windows server 2016 -,
- windows server 2016 1909,
- windows server 2016 2004,
- windows server 2016 20h2,
- windows server 2019 -
