SECURITY.NNOV: The Bat! <cr> bug

SECURITY.NNOV URL: http://www.security.nnov.ru
Topic: The Bat! <cr> bug
Application: The Bat! 1.51 (latest)
Vendor: RitLabs
Category: Denial of Service
Risk Factor: Low
Remote: Yes
Vendor Contacted: 13.04.2001
Software URL: http://www.thebat.net
Vendor URL: http://www.ritlabs.com

+Introduction:

The Bat! Is very convenient commercially available MUA for Windows
with lot of features.

+Details:

While RETRiving message via POP3 (IMAP isn't tested) The Bat!
incorrectly processes 0x0D (CR) character if it's not followed by
0x0A (LF). Probably each 0x0D character is treated as 2 octets and
The Bat! incorrectly calculates size of the message and the part of
message is treated as reply from POP3 server. The Bat! fails to
receive the rest of the messages and fails to delete received
messages from server. This leads to DoS against user's POP3 account.
Malformed message can emulate any POP3 server replies.

+Exploitation:

Extract attached "badmessage" and send it, e.g. using

cat badmessage | sendmail -U [email protected]

or copy it to user's mailbox.
This message causes The Bat! to show something like:

!13.04.2001, 17:51:01: FETCH - Server reports error. The response is: --ERR Wrong User: replace user
with your system administrator–

+Workaround:

use "Dispatch Mail on Server" feature to delete malformed message
from server or use different MUA.

+Solution:

No yet.

+Vendor:

RitLabs was contacted on April, 13 (happy Easter to you, guys). No
feedback yet.

This advisory is being provided to you under RFPolicy v.2 documented
at http://www.wiretrip.net/rfp/policy.html.

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