eggdrop/windrop remote crash vulnerability

[Thomas Sader <thommey@xxxxxxxxx>]

Affected software
-----------------

eggdrop (1.6.19 only, not 1.6.19+ctcpfix)
windrop (1.6.19 only, not 1.6.19+ctcpfix)
all eggdrop/windrop versions and packages which apply Nico Goldes
patch for CVE-2007-2807/SA25276 See: [1]

Vulnerability details
---------------------

The SA25276 patch ([1]) uses strncpy to fix a buffer overflow vulnerability
in src/mod/server.mod/servmsg.c (gotmsg). The last argument is not checked
for being non-negative, but that can happen if ctcpbuf is "". That causes
a remote crash vulnerability to be exploited by anyone connected to the same
IRC network as eggdrop. The SA25276 patch has been applied to the eggdrop1.6.18
debian package and was later adopted by Eggheads into eggdrop1.6.19.

One possible exploit anyone can send to the IRC server to crash eggdrop:

PRIVMSG eggdrop :\1\1

Resolution
----------

Upgrade to eggdrop/windrop 1.6.19+ctcpfix ([2],[3]), the current cvs versions,
or apply the ctcpfix patch at [2] before compiling.

Disclosure timeline
-------------------

2009-05-06: Vulnerability discovered and reported to Eggheads.
2009-05-06: Patch committed to cvs.
2009-05-14: New eggdrop and windrop version released with the fix applied.
2009-05-14: Public disclosure.

References
----------

[1] http://bugzilla.eggheads.org/show_bug.cgi?id=462
    http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=427157
    http://www.securityfocus.com/bid/24070
    http://secunia.com/advisories/25276
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2807

[2] http://www.eggheads.org/downloads/
[3] http://windrop.sourceforge.net/downloads.html


---
Thomas Sader (thommey)