cbcvebase.
CVE-2004-0380
published 2004-05-04

CVE-2004-0380: The MHTML protocol handler in Microsoft Outlook Express 5.5 SP2 through Outlook Express 6 SP1 allows remote attackers to bypass domain restrictions and execute…

PriorityP265critical10CVSS 2.0
AVNACLAuNCCICAC
ITWEXPLOITVulnCheck KEV
Exploited in the wild
EPSS
63.25%
99.1th percentile
The MHTML protocol handler in Microsoft Outlook Express 5.5 SP2 through Outlook Express 6 SP1 allows remote attackers to bypass domain restrictions and execute arbitrary code, as demonstrated on Internet Explorer using script in a compiled help (CHM) file that references the InfoTech Storage (ITS) protocol handlers such as (1) ms-its, (2) ms-itss, (3) its, or (4) mk:@MSITStore, aka the "MHTML URL Processing Vulnerability."

Affected

2 ranges
VendorProductVersion rangeFixed in
microsoftoutlook_express
microsoftoutlook_express

Detection & IOCsextracted from sources · hover to see the quote

urlms-its:mhtml:file://C:\ss.MHT!http://www.example.com//chm.chm::/files/launch.htm
urlms-its:mhtml:file://C:\foo.mht!${PATH}/EXPLOIT.CHM::/exploit.htm
urlhttp://ip3e83566f.speed.planet.nl/security/newone/exploit.htm
  • Detect exploit URI patterns combining MHTML and ITS protocol handlers — look for 'ms-its:mhtml:file://' in HTTP traffic, email bodies, or HTML content, as this is the canonical exploit string for CVE-2004-0380.
  • Flag any URI referencing ITS protocol handlers (ms-its:, ms-itss:, its:, mk:@MSITStore:) combined with MHTML or CHM file references, especially those pointing to remote hosts.
  • Monitor for delivery or execution of CHM files fetched via ITS protocol URI handlers from remote or untrusted locations, as the exploit chain delivers a malicious CHM containing scripted payloads.
  • Detect encoded variants of the exploit URI (percent-encoded characters in the ms-its/mhtml string) which may bypass simple string-match filters.
  • Inspect MHTML file URIs referencing non-existent resources (e.g., file://C:\<nonexistent>.MHT) as the vulnerability is triggered by the component failing to securely handle such references.
  • ·The vulnerability is present even if Microsoft Outlook has been removed as the default email client, because the affected MHTML handler component is shared with Internet Explorer.
  • ·Internet Explorer on Windows Server 2003 (with its hardened configuration) is still reported vulnerable to this attack.
  • ·Web browsers other than Internet Explorer may also invoke the OS-level URI handlers for the ITS protocol, broadening the attack surface beyond IE.

CVSS provenance

nvdv2.010.0CRITICALAV:N/AC:L/Au:N/C:C/I:C/A:C
vulncheck10.0CRITICAL
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