TITLE: Apache "Expect" Header Cross-Site Scripting Vulnerability

SECUNIA ADVISORY ID: SA21172

VERIFY ADVISORY: http://secunia.com/advisories/21172/

CRITICAL: Less critical

IMPACT: Cross Site Scripting

WHERE: >From remote

SOFTWARE:
Apache 1.3.x -- http://secunia.com/product/72/
Apache 2.0.x -- http://secunia.com/product/73/
Apache 2.2.x -- http://secunia.com/product/9633/

DESCRIPTION: Thiago Zaninotti has discovered a vulnerability in Apache HTTP Server, which can be exploited by malicious people to conduct cross-site scripting attacks. Input passed to the "Expect:" header is not properly sanitised before being returned to users. This can be exploited to execute arbitrary HTML and script code in a user's browser session in context of a vulnerable site.

The vulnerability affects versions prior to 1.3.35, 2.0.58, and 2.2.2.

Secunia has constructed a test, which is available at: http://secunia.com/expect_header_cross-site_scripting_vulnerability_test/

NOTE: This issue was originally not considered a vulnerability by the researcher and vendor due to the fact that no known vectors existed to exploit it. However, additional research by Amit Klein has proven that this can be exploited via a specially crafted Flash file.

SOLUTION: Update to version 1.3.35, 2.0.58, 2.2.2, or later.

PROVIDED AND/OR DISCOVERED BY: Thiago Zaninotti

Additional information about exploitation:

Amit Klein

ORIGINAL ADVISORY: Vendor bug report: http://svn.apache.org/viewvc?view=rev&revision=394965

Thiago Zaninotti: http://archives.neohapsis.com/archives/bugtraq/2006-05/0151.html

Amit Klein: http://archives.neohapsis.com/archives/bugtraq/2006-07/0425.html