cbcvebase.
CVE-2018-8625
published 2018-12-12

CVE-2018-8625: A remote code execution vulnerability exists in the way that the VBScript engine handles objects in memory, aka "Windows VBScript Engine Remote Code Execution…

PriorityP265high7.5CVSS 3.0
AVNACHPRNUIRSUCHIHAH
EXPLOIT
EPSS
43.76%
98.6th 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 Internet Explorer 9, Internet Explorer 11, Internet Explorer 10.

Affected

33 ranges· showing 25
VendorProductVersion rangeFixed in
microsoftinternet_explorer
microsoftinternet_explorer
microsoftinternet_explorer
microsoftinternet_explorer_10
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11
microsoftinternet_explorer_11

Detection & IOCsextracted from sources · hover to see the quote

urlhttps://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/46022.zip
  • Detect VBScript that defines a `Class_Terminate` sub which reassigns a shared outer-scope variable (e.g., `set a = c`) — this pattern is used to increment the reference counter of a target object inside the Erase callback.
  • Monitor for exploitation of `RegExp` built-in objects via reference-counter overflow in VBScript; the PoC specifically targets RegExp because built-in objects lack overflow protection unlike custom VBScript classes.
  • Flag Internet Explorer processes (iexplore.exe) rendering pages with VBScript that repeatedly creates and destroys arrays in a tight loop — the reference-counter overflow requires creating and destroying a new array per increment, which may manifest as sustained high CPU usage for ~2 hours.
  • ·The reference-counter overflow exploit requires sustained execution time (~2 hours on a typical CPU) unless a debugger is used to fast-forward the counter, meaning short-lived page visits are unlikely to complete exploitation.
  • ·Enabling page heap on iexplore.exe significantly slows the exploit, making it a viable mitigation/detection-delay measure in controlled environments.
  • ·Custom VBScript classes have built-in reference-counter overflow protection; the exploit therefore specifically targets built-in objects (e.g., RegExp) which lack this protection.

CVSS provenance

nvdv3.07.5HIGHCVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
nvdv2.07.6HIGHAV:N/AC:H/Au:N/C:C/I:C/A:C
vendor_msrc6.4MEDIUM
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