Secunia

Dr_insane has reported some vulnerabilities in PostMaster, which can be exploited by malicious people to detect the presence of local files, enumerate usernames, conduct cross-site scripting attacks and bypass certain security restrictions.

1) The web mail service returns different error messages depending on if a certain username is valid or not.

2) An error in the handling of the "wmm" parameter in "message.htm" can be exploited to enumerate filenames by examing the output.

Example:
http://[host]/message.htm?email=[user]&wmm=/../../../../../../[file]

3) An error in the authentication process can be exploited to login as an arbitrary user by specifying the "email" parameter in "message.htm".

4) Input passed to the "email" parameter in "message.htm" isn't properly sanitised before being returned to the user. This can be exploited to execute arbitrary HTML and script code in a user's browser session in context of a vulnerable site.

The vulnerabilities have been reported in version 4.2.2 (build 3.2.5). Other versions may also be affected.

Solution
Restrict access to the web mail interface.

Provided and/or discovered by
Dr_insane

Changelog
Further details available in Customer Area

Deep Links
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