Microsoft Win32k Privilege Escalation
CVE-2018-8453 is a high-severity vulnerability in Windows 7 from Microsoft, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected Windows 7 versions: 32-bit Systems Service Pack 1; x64-based Systems Service Pack 1. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on January 21, 2022, which means attacks have been observed in the wild, including in ransomware campaigns.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Check which version of Windows 7 you run against the affected versions below, and install the vendor's latest release.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on portal.msrc.microsoft.com for workarounds and exact fixed builds.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Microsoft | Windows 7 | 32-bit Systems Service Pack 1; x64-based Systems Service Pack 1 | Not stated |
| Microsoft | Windows Server 2012 R2 | (Server Core installation) | Not stated |
| Microsoft | Windows RT 8.1 | Windows RT 8.1 | Not stated |
| Microsoft | Windows Server 2008 | 32-bit Systems Service Pack 2; 32-bit Systems Service Pack 2 (Server Core installation); Itanium-Based Systems Service Pack 2; x64-based Systems Service Pack 2; x64-based Systems Service Pack 2 (Server Core installation) | Not stated |
| Microsoft | Windows Server 2019 | (Server Core installation) | Not stated |
| Microsoft | Windows Server 2012 | (Server Core installation) | Not stated |
| Microsoft | Windows 8.1 | 32-bit systems; x64-based systems | Not stated |
| Microsoft | Windows Server 2016 | (Server Core installation) | Not stated |
| Microsoft | Windows Server 2008 R2 | Itanium-Based Systems Service Pack 1; x64-based Systems Service Pack 1; x64-based Systems Service Pack 1 (Server Core installation) | Not stated |
| Microsoft | Windows 10 | 32-bit Systems; Version 1607 for 32-bit Systems; Version 1607 for x64-based Systems; Version 1703 for 32-bit Systems; Version 1703 for x64-based Systems; Version 1709 for 32-bit Systems; Version 1709 for x64-based Systems; Version 1803 for 32-bit Systems; and 4 more ranges | Not stated |
| Microsoft | Windows 10 Servers | version 1709 (Server Core Installation); version 1803 (Server Core Installation) | Not stated |
| Microsoft | Windows 10 1507 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1607 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1703 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1709 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1803 | Not specified in the record | Not stated |
| Microsoft | Windows 10 1809 | Not specified in the record | Not stated |
| Microsoft | Windows Server 1709 | Not specified in the record | Not stated |
| Microsoft | Windows Server 1803 | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
| CVSS 2.0 | 7.2 | High | NVD |
Official description
An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka "Win32k Elevation of Privilege Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2019, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-8453US Government Resource
Technical write-ups (may include proof of concept)
- packetstormsecurity.com/files/153669/Microsoft-Windows-NtUserSetWindowFNID-Win32k-User-Callback.htmlExploit, Third Party Advisory, VDB Entry
- securelist.com/cve-2018-8453-used-in-targeted-attackExploit, Technical Description, Third Party Advisory
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