Hypermail SSI Vulnerability

[qDefense Penetration Testing <advisories () qDefense com>]

Hypermail SSI Vulnerability
qDefense Advisory Number QDAV-2001-11-1

Product: Hypermail

Vendor: Hypermail Development (http://www.hypermail.org)

Severity: Remote; Attacker may be able to execute arbitrary commands on 
servers that run Hypermail and SSI

Vendor Status: Vendor contacted; patch released

In Short: Hypermail can be used to create arbitrary files, with arbitrary 
extensions, on the server, which may then possibly be used to execute SSI 
commands.


The current version of this document is available at 
http://qDefense.com/Advisories/QDAV-2001-11-1.html.

Details:

Hypermail converts e-mails into HTML. It is generally used to automatically 
create web archives of mailing lists. When e-mails are archived, 
attachments which are included are archived as well. The attachments are 
not modified before archival, and they are stored under the filename 
contained in the e-mail.

An attacker can therefore create an arbitrary file on the web server with 
an arbitrary extension. If the server supports SSI, an attacker can include 
SSI commands in a file, give it the SSI extension (normally .shtml), and 
mail it. This will create the desired file on the server. The attacker can 
than cause the server to execute those SSI commands by requesting the 
attachment.

It should be noted that creation of arbitrary files on a web server carries 
with it additional insecurites besides SSI, and therefore even servers that 
do not support SSI may be vulnerable.

Solution:

Hypermail has been patched to convert .shtml extensions to .html. As of 
this writing, no further correction has been taken.

Servers should never allow SSI, CGI, or any other type of server processed 
content in the hypermail directory.

(C) 2001 qDefense Penetration Testing. qDefense Penetration Testing is a 
subsidiary of Computer Modeling Corp.
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