Microsoft IIS Escape Character Parsing Vulnerability

Bugtraq ID:	886
Class:	Input Validation Error
CVE:
Remote:	Yes
Local:	Yes
Published:	Dec 21 1999 12:00AM
Updated:	Dec 21 1999 12:00AM
Credit:	Reported to Microsoft by the ACROS Security Team and publicized in a Microsoft Security Bulletin released December 21, 1999.
Vulnerable:	Microsoft Site Server Commerce Edition 3.0 i386 + Hancom Hancom Office 2007 0 - Microsoft BackOffice 4.5 - Microsoft BackOffice 4.5 + Microsoft Commercial Internet System 2.0 + Microsoft Site Server Commerce Edition 3.0 alpha - Microsoft Windows NT Enterprise Server 4.0 SP6a - Microsoft Windows NT Enterprise Server 4.0 SP6a - Microsoft Windows NT Enterprise Server 4.0 SP6 - Microsoft Windows NT Enterprise Server 4.0 SP6 - Microsoft Windows NT Enterprise Server 4.0 SP5 - Microsoft Windows NT Enterprise Server 4.0 SP5 - Microsoft Windows NT Enterprise Server 4.0 SP4 - Microsoft Windows NT Enterprise Server 4.0 SP4 - Microsoft Windows NT Enterprise Server 4.0 SP3 - Microsoft Windows NT Enterprise Server 4.0 SP3 - Microsoft Windows NT Server 4.0 SP6a - Microsoft Windows NT Server 4.0 SP6a - Microsoft Windows NT Server 4.0 SP6 - Microsoft Windows NT Server 4.0 SP6 - Microsoft Windows NT Server 4.0 SP5 - Microsoft Windows NT Server 4.0 SP5 - Microsoft Windows NT Server 4.0 SP4 - Microsoft Windows NT Server 4.0 SP4 - Microsoft Windows NT Server 4.0 SP3 - Microsoft Windows NT Server 4.0 SP3 Microsoft Site Server Commerce Edition 3.0 alpha - Microsoft BackOffice 4.5 - Microsoft BackOffice 4.5 - Microsoft IIS 4.0 - Microsoft Windows NT 4.0 - Microsoft Windows NT Enterprise Server 4.0 SP6a - Microsoft Windows NT Enterprise Server 4.0 SP6a - Microsoft Windows NT Enterprise Server 4.0 SP6 - Microsoft Windows NT Enterprise Server 4.0 SP6 - Microsoft Windows NT Enterprise Server 4.0 SP5 - Microsoft Windows NT Enterprise Server 4.0 SP5 - Microsoft Windows NT Enterprise Server 4.0 SP4 - Microsoft Windows NT Enterprise Server 4.0 SP4 - Microsoft Windows NT Enterprise Server 4.0 SP3 - Microsoft Windows NT Enterprise Server 4.0 SP3 - Microsoft Windows NT Server 4.0 SP6a - Microsoft Windows NT Server 4.0 SP6a - Microsoft Windows NT Server 4.0 SP6 - Microsoft Windows NT Server 4.0 SP6 - Microsoft Windows NT Server 4.0 SP5 - Microsoft Windows NT Server 4.0 SP5 - Microsoft Windows NT Server 4.0 SP4 - Microsoft Windows NT Server 4.0 SP4 - Microsoft Windows NT Server 4.0 SP3 - Microsoft Windows NT Server 4.0 SP3 Microsoft IIS 4.0 + Cisco Building Broadband Service Manager (BBSM) 5.0 + Cisco Building Broadband Service Manager (BBSM) 5.0 + Cisco Call Manager 3.0 + Cisco Call Manager 3.0 + Cisco Call Manager 2.0 + Cisco Call Manager 2.0 + Cisco Call Manager 1.0 + Cisco Call Manager 1.0 + Cisco ICS 7750 + Cisco ICS 7750 + Cisco IP/VC 3540 Video Rate Matching Module + Cisco IP/VC 3540 Video Rate Matching Module + Cisco Unity Server 2.4 + Cisco Unity Server 2.4 + Cisco Unity Server 2.3 + Cisco Unity Server 2.3 + Cisco Unity Server 2.2 + Cisco Unity Server 2.2 + Cisco Unity Server 2.0 + Cisco Unity Server 2.0 + Cisco uOne 4.0 + Cisco uOne 4.0 + Cisco uOne 3.0 + Cisco uOne 3.0 + Cisco uOne 2.0 + Cisco uOne 2.0 + Cisco uOne 1.0 + Cisco uOne 1.0 + Hancom Hancom Office 2007 0 + Hancom Hancom Office 2007 0 + Microsoft BackOffice 4.5 + Microsoft BackOffice 4.5 + Microsoft Windows NT 4.0 Option Pack + Microsoft Windows NT 4.0 Option Pack
Not Vulnerable:

Microsoft IIS Escape Character Parsing Vulnerability

IIS accepts escaped characters that are not valid hexadecimal digits. All webservers that are compliant with RFC 1738 accept hexadecimal digits that are preceded by a percent sign, but IIS will also accept invalid hex digits and translate some of them into valid ASCII characters. This provides a third means of constructing URLs (plaintext, valid hex, and invalid hex) that may be used to bypass third-party access control mechanisms and intrusion detection systems. This issue does not provide a means of compromising the IIS server itself.

Microsoft IIS Escape Character Parsing Vulnerability

Currently the SecurityFocus staff are not aware of any exploits for this issue. If you feel we are in error or are aware of more recent information, please mail us at: [email protected].

Microsoft IIS Escape Character Parsing Vulnerability

Solution:
Microsoft has released a patch for this issue, available at:
Intel:
http://www.microsoft.com/Downloads/Release.asp?ReleaseID=16357
Alpha:
http://www.microsoft.com/Downloads/Release.asp?ReleaseID=16358

Microsoft IIS Escape Character Parsing Vulnerability

References:

• Frequently Asked Questions: Microsoft Security Bulletin MS99-061 (Microsoft)