cbcvebase.
CVE-2018-8544
published 2018-11-14

CVE-2018-8544: A remote code execution vulnerability exists in the way that the VBScript engine handles objects in memory, aka "Windows VBScript Engine Remote Code Execution…

PriorityP273high8.8CVSS 3.0
AVNACLPRNUIRSUCHIHAH
EXPLOIT
EPSS
47.56%
98.7th percentile
A remote code execution vulnerability exists in the way that the VBScript engine handles objects in memory, aka "Windows VBScript Engine Remote Code Execution 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.

Affected

59 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
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10_servers
microsoftwindows_10_servers
microsoftwindows_7
microsoftwindows_7
microsoftwindows_8.1

Detection & IOCsextracted from sources · hover to see the quote

  • Trigger pattern: VBScript Class_Terminate destructor calls RemoveAll on a Scripting.Dictionary object that holds a reference to the class instance, causing a use-after-free in OLEAUT32!VariantClear when the item is reassigned.
  • Crash occurs at OLEAUT32!VariantClear+0xdb writing to a freed heap address; monitor for access violations in OLEAUT32!VariantClear called from scrrun!VBADictionary::put_Item in an Internet Explorer / VBScript context.
  • Attack vector is a web-based scenario via Internet Explorer; monitor for VBScript execution inside iexplore.exe that instantiates Scripting.Dictionary (scrrun.dll) and triggers Class_Terminate with dictionary manipulation.
  • ActiveX 'safe for initialization' controls embedded in Office documents hosting the IE rendering engine are also an attack vector; monitor for MSHTML-hosted VBScript executing scrrun!VBADictionary operations.
  • ·The exploit PoC was demonstrated on a 32-bit Internet Explorer process; register values and heap addresses in the crash dump are specific to that environment and will differ on 64-bit or patched systems.
  • ·Exploitation likelihood is rated 'More Likely' for both latest and older software releases by Microsoft, meaning unpatched systems across a wide Windows version range remain at elevated risk.

CVSS provenance

nvdv3.08.8HIGHCVSS:3.0/AV:N/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_msrc7.5HIGH
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