gnuserv MIT-MAGIC-COOKIE Remote Buffer Overflow Vulnerability

BID:2333

Info

gnuserv MIT-MAGIC-COOKIE Remote Buffer Overflow Vulnerability

Bugtraq ID: 2333
Class: Boundary Condition Error
CVE:
Remote: Yes
Local: No
Published: Feb 01 2001 12:00AM
Updated: Feb 01 2001 12:00AM
Credit: This problem was discovered by Klaus Frank <[email protected]>, and announced to Bugtraq in a Mandrake Security Advisory on January 31, 2001.
Vulnerable: XEmacs Development Team XEmacs 21.2.42
Redhat Linux 6.2 sparc
Redhat Linux 6.2 i386
Redhat Linux 6.2 alpha
Martin Schwenkes gnuserv 3.11
+ XEmacs Development Team XEmacs 21.2.42
+ XEmacs Development Team XEmacs 2.1.13
Mandriva Linux Mandrake 7.2
Mandriva Linux Mandrake 7.1
Mandriva Linux Mandrake 7.0
Mandriva Linux Mandrake 6.1
Mandriva Linux Mandrake 6.0
MandrakeSoft Corporate Server 1.0.1
Not Vulnerable:

Discussion

gnuserv MIT-MAGIC-COOKIE Remote Buffer Overflow Vulnerability

gnuserv is a freely available client server package included with xemacs. gnuserv is currently maintained by Jan Vroonhof.

A problem with gnuserv could allow a remote user to arbitrarily execute code. gnuserv allows for remote connectivity to a local session using the MIT-MAGIC-COOKIE authentication mechanism. However, the server places trust in the remote side of the connection to send a magic cookie within the size limitations. Sanity checks are not done on the cookie, which could allow a buffer overflow in the buffer holding the cookie, or alter the prefix length of authentication to a new size of 1 byte, making it possible to launch a brute-force attack against a trivial authentication.

This makes it possible for a remote user to initiate a connection to the gnuserv server, and potentially execute code as the UID of the server.

Exploit / POC

gnuserv MIT-MAGIC-COOKIE Remote Buffer Overflow Vulnerability

Currently the SecurityFocus staff are not aware of any exploits for this issue. If you feel we are in error or are aware of more recent information, please mail us at: [email protected] <mailto:[email protected]>.

Solution / Fix

gnuserv MIT-MAGIC-COOKIE Remote Buffer Overflow Vulnerability

Solution:
Updates available:


MandrakeSoft Corporate Server 1.0.1

Martin Schwenkes gnuserv 3.11

Mandriva Linux Mandrake 6.0

Mandriva Linux Mandrake 6.1

Redhat Linux 6.2 sparc

Redhat Linux 6.2 alpha

Redhat Linux 6.2 i386

Mandriva Linux Mandrake 7.0

Mandriva Linux Mandrake 7.1

Mandriva Linux Mandrake 7.2

References

gnuserv MIT-MAGIC-COOKIE Remote Buffer Overflow Vulnerability

References:
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