Attacker Value
Moderate
(1 user assessed)
Exploitability
Moderate
(1 user assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Network
1

CVE-2021-24088

Disclosure Date: February 25, 2021
Add MITRE ATT&CK tactics and techniques that apply to this CVE.
Privilege Escalation
Techniques
Validation
Validated
Validated

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2
Ratings
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
Base Score:
8.8 High
Impact Score:
5.9
Exploitability Score:
2.8
Vector:
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Network
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Vendors

  • Microsoft

Products

  • Windows Server, version 20H2 (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,
  • 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 Server, version 1909 (Server Core installation),
  • 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)

Additional Info

Technical Analysis