CVE-2011-3190 Apache Tomcat Authentication bypass and information disclosure

Severity: Important

Vendor: The Apache Software Foundation

Versions Affected:
- Tomcat 7.0.0 to 7.0.20
- Tomcat 6.0.0 to 6.0.33
- Tomcat 5.5.0 to 5.5.33
- Earlier, unsupported versions may also be affected

Description:
Apache Tomcat supports the AJP protocol which is used with reverse
proxies to pass requests and associated data about the request from the
reverse proxy to Tomcat. The AJP protocol is designed so that when a
request includes a request body, an unsolicited AJP message is sent to
Tomcat that includes the first part (or possibly all) of the request
body. In certain circumstances, Tomcat did not process this message as a
request body but as a new request. This permitted an attacker to have
full control over the AJP message which allowed an attacker to (amongst
other things):
- insert the name of an authenticated user
- insert any client IP address (potentially bypassing any client IP
address filtering)
- trigger the mixing of responses between users

The following AJP connector implementations are not affected:
org.apache.jk.server.JkCoyoteHandler (5.5.x - default, 6.0.x - default)

The following AJP connector implementations are affected:

org.apache.coyote.ajp.AjpProtocol (6.0.x, 7.0.x - default)
org.apache.coyote.ajp.AjpNioProtocol (7.0.x)
org.apache.coyote.ajp.AjpAprProtocol (5.5.x, 6.0.x, 7.0.x)

Further, this issue only applies if all of the following are are true
for at least one resource:
- POST requests are accepted
- The request body is not processed


Example: See https://issues.apache.org/bugzilla/show_bug.cgi?id=51698

Mitigation:
Users of affected versions should apply one of the following mitigations:
- Upgrade to a version of Apache Tomcat that includes a fix for this
issue when available
- Apply the appropriate patch
  - 7.0.x http://svn.apache.org/viewvc?rev=1162958&view=rev
  - 6.0.x http://svn.apache.org/viewvc?rev=1162959&view=rev
  - 5.5.x http://svn.apache.org/viewvc?rev=1162960&view=rev
- Configure the reverse proxy and Tomcat's AJP connector(s) to use the
requiredSecret attribute
- Use the org.apache.jk.server.JkCoyoteHandler AJP connector (not
available for Tomcat 7.0.x)

Credit:
The issue was reported via Apache Tomcat's public issue tracker.
The Apache Tomcat security team strongly discourages reporting of
undisclosed vulnerabilities via public channels. All Apache Tomcat
security vulnerabilities should be reported to the private security team
mailing list: security@tomcat.apache.org

References:
http://tomcat.apache.org/security.html
http://tomcat.apache.org/security-7.html
http://tomcat.apache.org/security-6.html
http://tomcat.apache.org/security-5.html
https://issues.apache.org/bugzilla/show_bug.cgi?id=51698