NT IIS Double Byte Code Page Vulnerability

Bugtraq ID:	477
Class:	Design Error
CVE:
Remote:	Yes
Local:	No
Published:	Jun 24 1999 12:00AM
Updated:	Jun 24 1999 12:00AM
Credit:	This vulnerability was discovered by Microsoft.
Vulnerable:	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 Microsoft IIS 3.0 - Microsoft Windows NT 4.0 SP6a - Microsoft Windows NT 4.0 SP6a - Microsoft Windows NT 4.0 SP6 - Microsoft Windows NT 4.0 SP6 - Microsoft Windows NT 4.0 SP5 - Microsoft Windows NT 4.0 SP5 - Microsoft Windows NT 4.0 SP4 - Microsoft Windows NT 4.0 SP4 - Microsoft Windows NT 4.0 SP3 - Microsoft Windows NT 4.0 SP3 - Microsoft Windows NT 4.0 SP2 - Microsoft Windows NT 4.0 SP2 - Microsoft Windows NT 4.0 SP1 - Microsoft Windows NT 4.0 SP1 - Microsoft Windows NT 4.0 - Microsoft Windows NT 4.0
Not Vulnerable:	Microsoft IIS 2.0 + Microsoft Windows NT 4.0 + Microsoft Windows NT 4.0

NT IIS Double Byte Code Page Vulnerability

This vulnerability could allow a web site viewer to obtain the source code for .asp and similar files if the server's default language (Input Locale) is set to Chinese, Japanese or Korean. How this works is as follows:

IIS checks the extension of the requested file to see if it needs to do any processing before delivering the information. If the requested extension is not on it's list, it then makes any language-based calculations, and delivers the file. If a single byte is appended to the end of the URL when IIS to set to use one of the double-byte language packs (Chinese, Japanese, or Korean) the language module will strip it as invalid, then look for the file. Since the new URL now points to a valid filename, and IIS has already determined that this transaction requires no processing, the file is simply delivered as is, exposing the source code.

NT IIS Double Byte Code Page Vulnerability

Request a URL of a known-good file that requires server processing, then append a hex value between x81 and xfe to the URL. For example: <http://myhost/main.asp%81>. If your server is vulnerable you will receive back the source code of your .asp file.

NT IIS Double Byte Code Page Vulnerability

References:

• Frequently Asked Questions: Microsoft Security Bulletin (MS99-022) (Microsoft)
  
• Q233335 - Page Contents Visible When Certain Characters are at End of URL (Microsoft)