cbcvebase.
CVE-2018-8413
published 2018-10-10

CVE-2018-8413: A remote code execution vulnerability exists when "Windows Theme API" does not properly decompress files, aka "Windows Theme API Remote Code Execution…

PriorityP262high7.8CVSS 3.0
AVLACLPRNUIRSUCHIHAH
EXPLOIT
EPSS
46.41%
98.7th percentile
A remote code execution vulnerability exists when "Windows Theme API" does not properly decompress files, aka "Windows Theme API Remote Code Execution Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2019, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers.

Affected

51 ranges· showing 25
VendorProductVersion rangeFixed in
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10_servers
microsoftwindows_10_servers
microsoftwindows_7
microsoftwindows_7
microsoftwindows_8.1
microsoftwindows_8.1
microsoftwindows_rt_8.1
microsoftwindows_server_2008

Detection & IOCsextracted from sources · hover to see the quote

filenameC00L.themepack
filenamethemepack000.h
path\roaming\microsoft\windows\start menu\programs\startup\
filenameabc.hta:.theme
commandpath traversal via ..\..\..\..\..\..\roaming\microsoft\windows\start menu\programs\startup\ in CAB-formatted .themepack
bytes
4D53434600000000AB010000000000002C000000000000000301010001000000000000009500000001000100930100000000000000003C508108200061612E2E5C2E2E5C2E2E5C2E2E5C2E2E5C2E2E5C726F616D696E675C6D6963726F736F66745C77696E646F77735C7374617274206D656E755C70726F6772616D735C737461727475705C6162632E6874613A2E7468656D65
  • Detect .themepack files (CAB format) containing path traversal sequences (e.g., ..\..\) in embedded filenames, particularly targeting the Startup folder path.
  • Detect .themepack CAB archives containing filenames using NTFS Alternate Data Stream notation (e.g., 'filename.hta:.theme') to smuggle non-.theme file extensions past the parser.
  • Monitor for unexpected file creation events (especially .hta files) in the Windows Startup directory (\roaming\microsoft\windows\start menu\programs\startup\) originating from the theme parsing process.
  • Flag .themepack files whose CAB content begins with the magic bytes 4D534346 (MSCF) and contains embedded path traversal strings targeting the Startup folder.
  • Alert on creation of the temp file 'themepack000.h' in the user's %TEMP% directory, which is an artifact of the PoC exploit dropper.
  • ·The vulnerability requires user interaction — the victim must open a specially crafted .themepack file. Drive-by exploitation without user action is not possible.
  • ·The parser enforces a .theme extension on dropped files, but this restriction is bypassable via NTFS Alternate Data Streams — detection logic must account for ADS-style filenames inside CAB archives.
  • ·The malicious .themepack must still contain a valid .theme file to pass parser validation; purely malicious archives without a legitimate .theme entry will not trigger the vulnerability.

CVSS provenance

nvdv3.07.8HIGHCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
nvdv2.09.3CRITICALAV:N/AC:M/Au:N/C:C/I:C/A:C
vendor_msrc5.0MEDIUM
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