https://www.exploit-db.com/exploits/20105
http://www.cnnvd.org.cn/web/xxk/ldxqById.tag?CNNVD=CNNVD-200007-072

Linux系统中的pam_consolePAM模块存在漏洞。当陈列管理员如gdm或者kdm具有XDMCP有效时，用户利用该漏洞访问系统控制且重新启动系统。

source: http://www.securityfocus.com/bid/1513/info

There is a vulnerability in the Linux pam_console module that could allow an attacker to remotely reboot the workstation or perform other actions limited to local users.
If a workstation is configured to use a display manager (xdm, gdm, kdm, etc.) AND has XDMCP enabled, it is possible for a user who logs in remotely to use Xnest -query to log in on display :1, which is recognized as the system console. This vulnerability is only present if the workstation is running a graphical login manager such as gdm or kdm. 


This description of how to replicate the problem was posted to RedHat's Bugzilla bug-tracking system by [email protected]:
1. ssh into the server, allowing ssh to establish a secure forwarded X connection. If no one else is using display number 0, you'll end up with a DISPLAY value of "host:0.0".
2. Invoke "Xnest -query localhost" on the remote machine.
3. Log in, starting a Gnome session.
4. From the Gnome panel, select "logout". You'll be presented with the option of shutting down or rebooting the server.

Another description, this one from Andreas Hasenack <[email protected]>:
1. login remotely (X -broadcast) (have gdm, kdm, whatever running with XDMCP enabled somewhere)
2. after login, start Xnest with -broadcast again, for example
3. login again, now you will be using display :1
4. this is treated as a console user, and commands only available to console users can be run, such as reboot.

来源:XF
名称:linux-pam-console
链接:http://xforce.iss.net/static/5001.php
来源:BID
名称:1513
链接:http://www.securityfocus.com/bid/1513
来源:REDHAT
名称:RHSA-2000:044
链接:http://www.redhat.com/support/errata/RHSA-2000-044.html
来源:BUGTRAQ
名称:20000801MDKSA-2000:029pamupdate
链接:http://archives.neohapsis.com/archives/bugtraq/2000-07/0455.html
来源:BUGTRAQ
名称:20000727CONECTIVALINUXSECURITYANNOUNCEMENT-PAM
链接:http://archives.neohapsis.com/archives/bugtraq/2000-07/0398.html