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

Package:	at	
Issue Date: 	January 27, 2002	
Priority:	high		
Advisory ID: 	YDU-20020127-9


1. 	Topic:

	This updated at package fixes two minor problems and one major
	problem where the environment can get wiped out prior to the execution of a
	scheduled command.

	This package also fixes a potential security vulnerability 
	which can result in heap corruption.


2. 	Problem:

	A server running the latest version of at could have commands
	that depend on the current environment (for example, the PATH) which would
	then fail or run incorrectly because the environment would not be
	accessible when the command was executed at a later time.

	Additionally, a malicious local user could specify an execution
	time in a carefully drafted format causing a heap corruption bug.
	Since the at command is installed as setuid root this bug can be
	exploited.

	The Common Vulnerabilities and Exposures project (cve.mitre.org) has
	assigned the name CAN-2002-0004 to this issue. Thanks to zen-parse for
	reporting this vulnerability.

	In addition to the fixed heap corruption, file handling security on all
	versions of at has been improved by adding the O_EXCL (exclusive) option to
	an open system call.
	(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 at 

   	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 at-3.1.8-23.ppc.rpm


4. Verification

MD5 checksum			  Package
--------------------------------  ----------------------------
17a261261a71b21bae4ccf7113261ebb  ppc/at-3.1.8-23.ppc.rpm
6022f0beaf1f2dcb7949460f296e191b  SRPMS/at-3.1.8-23.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