J-Security Center

Title: Microsoft IIS Executable File Parsing Vulnerability

Severity: HIGH

Description:

When Microsoft IIS receives a valid request for an executable file, the filename is then passed onto the underlying operating system which executes the file. In the event that IIS receives a specially formed request for an executable file followed by operating system commands, IIS will proceed to process the entire string rather than rejecting it. Thus, a malicious user may perform system commands through cmd.exe under the context of the IUSR_machinename account which could possibly lead to privilege escalation, deletion, addition, and modification of files, or full compromise of the server.

In order to establish successful exploitation, the file requested must be an existing .bat or .cmd file residing in a folder that the user possesses executable permissions to.

Update (November 27, 2000): Georgi Guninski has discovered new variants of this vulnerability that have appeared after applying the patch (Q277873) supplied by Microsoft. Please see 'Exploit' for further details.

Update (December 7, 2000): Billy Nothern has discovered that the commands can also be parsed through ActiveState Perl. Please see his Bugtraq posted located under 'Credit' for further information.

**UPDATE**: It is believed that an aggressive worm may be in the wild that actively exploits this vulnerability.

Affected Products:

  • Cisco Building Broadband Service Manager 5.0.0
  • Cisco Call Manager 1.0.0
  • Cisco Call Manager 2.0.0
  • Cisco Call Manager 3.0.0
  • Cisco ICS 7750 0.0.0
  • Cisco IP/VC 3540 Video Rate Matching Module 0.0.0
  • Cisco Unity Server 2.0.0
  • Cisco Unity Server 2.2.0
  • Cisco Unity Server 2.3.0
  • Cisco Unity Server 2.4.0
  • Cisco uOne 1.0.0
  • Cisco uOne 2.0.0
  • Cisco uOne 3.0.0
  • Cisco uOne 4.0.0
  • Microsoft BackOffice 4.0.0
  • Microsoft BackOffice 4.5.0
  • Microsoft IIS 4.0.0
  • Microsoft IIS 5.0
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional
  • Microsoft Windows 2000 Server
  • Microsoft Windows NT 4.0 Option Pack

References:

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