cbcvebase.
CVE-2014-6363
published 2014-12-11

CVE-2014-6363: vbscript.dll in Microsoft VBScript 5.6 through 5.8, as used with Internet Explorer 6 through 11 and other products, allows remote attackers to execute…

PriorityP261critical9.3CVSS 2.0
AVNACMAuNCCICAC
EXPLOIT
EPSS
28.44%
97.9th percentile
vbscript.dll in Microsoft VBScript 5.6 through 5.8, as used with Internet Explorer 6 through 11 and other products, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site, aka "VBScript Memory Corruption Vulnerability."

Affected

9 ranges
VendorProductVersion rangeFixed in
microsoftinternet_explorer
microsoftinternet_explorer
microsoftinternet_explorer
microsoftinternet_explorer
microsoftinternet_explorer
microsoftinternet_explorer
microsoftvbscript
microsoftvbscript
microsoftvbscript

Detection & IOCsextracted from sources · hover to see the quote

filenamevbscript.dll
commandoRegExp.Pattern = "A|()*?$"
  • Trigger condition: VBScript RegExp.Execute called with a pattern containing alternation and zero-or-more quantifier (e.g. 'A|()*?$') against a string of 0x11 or more repeated characters, causing >16 CMatch objects to be allocated and triggering use of uninitialized memory in error-handling cleanup path of CRegExp::Execute.
  • Heap manipulation technique: attacker allocates msvcrt heap blocks of size 0x44 bytes (x86) by executing RegExp patterns with a calculated number of sub-match groups to control block size and content, then frees them before triggering the vulnerability to control uninitialized CMatchBlock memory.
  • The exploit uses the string marker 'PWND' as the RegExp match anchor to control match offsets and thus heap block contents during heap feng-shui preparation.
  • CMatchBlock structure size is 0x44 bytes on x86 and 0x88 bytes on x64; monitor for repeated msvcrt heap allocations of these exact sizes during VBScript RegExp execution as a sign of exploit heap preparation.
  • Exploitation path goes through CRegExp::Execute in vbscript.dll; monitor for Internet Explorer or script host processes (CScript.exe, WScript.exe) calling into vbscript.dll CRegExp::Execute with subsequent access violations or heap corruption indicative of uninitialized pointer dereference.
  • ·Heap feng-shui via JavaScript/VBScript strings is NOT effective for this vulnerability because strings are allocated through OLEAUT32, while CMatchBlock structures are allocated through msvcrt (a separate heap). Standard string-based heap spray techniques will not manipulate the relevant heap.
  • ·The PoC exploit does not implement DEP or ASLR bypass; the 'shellcode' is only INT3 instructions. Real-world exploitation requires additional mitigations bypass on top of the heap manipulation primitive.
  • ·The vulnerability affects VBScript 5.6–5.8 as used in Internet Explorer 6–11, IIS (via ASP), CScript.exe, and WScript.exe. The attack surface is broader than just browser-based exploitation.
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