Xlockmore 4.16 Buffer Overflow Vulnerability
BID:1267
Info
Xlockmore 4.16 Buffer Overflow Vulnerability
| Bugtraq ID: | 1267 |
| Class: | Boundary Condition Error |
| CVE: | |
| Remote: | No |
| Local: | Yes |
| Published: | May 29 2000 12:00AM |
| Updated: | May 29 2000 12:00AM |
| Credit: | First made public in Network Associates COVERT Labs Security Advisory COVERT-2000-06. |
| Vulnerable: |
David Bagley xlock 4.16 |
| Not Vulnerable: |
David Bagley xlock 4.16.1 |
Discussion
Xlockmore 4.16 Buffer Overflow Vulnerability
xlock is an X11 utility used to lock Xwindows displays until the password of the user running X is entered correctly. Of course, in order to perform the password-check xlock must be setuid root and have access to the shadowed passwd file. In the xlockmore distributions versions prior to 4.16.1, a buffer overflow vulnerability was present in xlock that permitted a user to view parts of the shadowed passwd file. This is achieved by overwriting (with an oversized -mode argument) a global variable storing a pointer to a string printed in the "usage" output. The pointer would be overwritten with an address pointing to the shadowed passwd data. With the long argument, xlock would find and an error in the command syntax and exit, printing the usage information (along with the shadowed passwd text).
xlock is an X11 utility used to lock Xwindows displays until the password of the user running X is entered correctly. Of course, in order to perform the password-check xlock must be setuid root and have access to the shadowed passwd file. In the xlockmore distributions versions prior to 4.16.1, a buffer overflow vulnerability was present in xlock that permitted a user to view parts of the shadowed passwd file. This is achieved by overwriting (with an oversized -mode argument) a global variable storing a pointer to a string printed in the "usage" output. The pointer would be overwritten with an address pointing to the shadowed passwd data. With the long argument, xlock would find and an error in the command syntax and exit, printing the usage information (along with the shadowed passwd text).
Exploit / POC
Xlockmore 4.16 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].
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].
Solution / Fix
Xlockmore 4.16 Buffer Overflow Vulnerability
Solution:
This vulnerability has been fixed in (at least) the NetBSD package sources.
To remove the package:
pkg_delete -v xlockmore
To build / install the new version:
cd pkgsrc/x11/xlockmore; make clean; make install
NetBSD binaries are available at:
ftp://ftp.netbsd.org/pub/NetBSD/packages/pkgsrc/x11/xlockmore/README.html
Mandrake Linux:
To upgrade automatically, use ? MandrakeUpdate ?. If you want to upgrade manually, download the updated package from one of the FTP server mirrors and uprade with "rpm -Uvh package_name". All mirrors are listed on http://www.mandrake.com/en/ftp.php3 Updated packages are available in the "updates/" directory.
For example, if you are looking for an updated RPM package for Mandrake 7.0, look for it in: updates/7.0/RPMS/
Solution:
This vulnerability has been fixed in (at least) the NetBSD package sources.
To remove the package:
pkg_delete -v xlockmore
To build / install the new version:
cd pkgsrc/x11/xlockmore; make clean; make install
NetBSD binaries are available at:
ftp://ftp.netbsd.org/pub/NetBSD/packages/pkgsrc/x11/xlockmore/README.html
Mandrake Linux:
To upgrade automatically, use ? MandrakeUpdate ?. If you want to upgrade manually, download the updated package from one of the FTP server mirrors and uprade with "rpm -Uvh package_name". All mirrors are listed on http://www.mandrake.com/en/ftp.php3 Updated packages are available in the "updates/" directory.
For example, if you are looking for an updated RPM package for Mandrake 7.0, look for it in: updates/7.0/RPMS/
References
Xlockmore 4.16 Buffer Overflow Vulnerability
References:
References:
- NetBSD Security Page (NetBSD)
- Xlockmore Homepage (David Bagely)