TITLE:
MDaemon WorldClient Inbox Denial of Service Weakness

SECUNIA ADVISORY ID:
SA17990

VERIFY ADVISORY:
http://secunia.com/advisories/17990/

CRITICAL:
Less critical

IMPACT:
DoS

WHERE:
>From remote

SOFTWARE:
MDaemon 8.x
http://secunia.com/product/5407/

DESCRIPTION:
dr_insane has discovered a weakness in MDaemon, which can be
exploited by malicious people to cause a DoS (Denial of Service).

The weakness is caused due to an error in the WorldClient webmail
when displaying the user's inbox when the "Subject" header of a
received email contains Javascript tags. This can be exploited to
prevent a user from correctly accessing his Inbox from the webmail
via a specially crafted email containing "<script></script>" in the
"Subject" field.

The weakness has been confirmed in version 8.1.3. Other versions may
also be affected.

Note: It is also reportedly possible to logout another user if the 7
uppercase-only Session ID of that user is guessed correctly, and the
other user is accessing the webmail server from the same IP address
as the attacker (e.g. via the same proxy server).

SOLUTION:
Filter emails containing potentially malicious scripts with an email
filtering gateway.

Removing the malicious email, e.g. by deleting it via IMAP or POP3,
would allow the inbox to be accessible again.

PROVIDED AND/OR DISCOVERED BY:
dr_insane

ORIGINAL ADVISORY:
http://www.ipomonis.com/advisories.htm

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