Yellow Dog Linux Security Announcement
--------------------------------------

Package:	xchat	
Issue Date: 	January 27, 2002	
Priority:	medium		
Advisory ID: 	YDU-20020127-2


1. 	Topic:

	Versions of xchat prior to version 1.8.7 contain a vulnerability
	which allows an attacker to cause a vulnerable client to execute
	arbitrary IRC server commands as if the vulnerable user had typed
	them.

	This security erratum updates xchat to version 1.8.7, which is
	not vulnerable to this attack


2. 	Problem:

	xchat is a popular IRC client. Recently xchat has been
	found to contain a bug in the CTCP PING handling code which can
	be exploited to execute IRC commands on the IRC server as the
	vulnerable user. This can be used for example by an attacker
	to /op or /deop, to /kick someone out of a channel, to force the
	vulnerable user out of the channel with a /part, to change
	channel modes via the /mode command, or to impersonate a user
	via private /msg commands.

	This bug does not appear to allow an attacker to execute commands
	on the vulnerable computer, just to force IRC server commands to
	be run as if the vulnerable user had typed them.

	All previous versions of xchat are vulnerable, however only the 1.4.*
	versions are vulnerable by default. With later versions (1.6.*, 1.8.*),
	xchat is not vulnerable unless the user has enabled the client side
	"percascii" variable with the command "/set percascii 1"
	(from Red Hat advisory)	


3. 	Solution:

   	a) Updating via yup...
   	We suggest that you use the Yellow Dog Update Program (yup)
   	to keep your system up-to-date. The following command(s) will
   	automatically retrieve and install the fixed version of
   	this update onto your system:

   		yup update xchat 
 

   	b) Updating manually...
   	The update can also be retrieved manually from our ftp site
   	below along with the rpm command that should be used to install
   	the update.  (Please use a mirror site)

   		ftp://ftp.yellowdoglinux.com/pub/yellowdog/updates/yellowdog-2.1/ppc/
		rpm -Fvh xchat-1.8.7-1.72.0.ppc.rpm


4. Verification

MD5 checksum			  Package
--------------------------------  ----------------------------
75a3959a60589c2b06464a4afdc84150  ppc/xchat-1.8.7-1.72.0.ppc.rpm
7c31379536c3a9a1a7dc96eea6939f8f  SRPMS/xchat-1.8.7-1.72.0.src.rpm

If you wish to verify that each package has not been corrupted or tampered with,
examine the md5sum with the following command: rpm --checksig --nogpg filename


5. Misc.

Terra Soft has setup a moderated mailing list where these security, bugfix, and package
enhancement announcements will be posted. See http://lists.yellowdoglinux.com/ for more
information.

For information regarding the usage of yup, the Yellow Dog Update Program, see 
http://http://www.yellowdoglinux.com/support/solutions/ydl_general/yup.shtml