Title: XFree86 xdm Buffer Overflow Vulnerability
Severity: HIGH
Description:
Xdm is the X11 display manager, used for managing X11 user sessions. The XFree86 implementation of xdm contains a possibly exploitable buffer overflow condition.
The overflow is believed to exist when a remote Xserver is attempting to begin an xdm session via XDMCP.
The vulnerability is due to the use of the 'sprintf()' libc function. The 'sprintf' function allows for a string to be created using printf format specifiers. There is no bounds checking done by 'sprintf()' to ensure that the created string is not larger than the buffer allocated for the new string. A buffer overflow condition can be triggered if externally supplied data corresponding to format specifiers can cause the created string to be too large.
Xservers connecting to servers running xdm may be able to exploit such a condition. When the server running xdm fails to send a display to a remote Xserver attempting to initiate a session, an error message is logged. This error message is created via 'sprintf()' and contains externally supplied data, including the remote DISPLAY name.
Malicious Xservers may be able to trigger a buffer overflow by providing a DISPLAY name excessive in length. It may be possible to overwrite parts or all of the function stack frame and force execution of supplied shellcode.
Successful exploitation of this vulnerability may provide an attacker with root access on the target host.
Though uncomfirmed, it is most likely required that the attacking host be authorized to connect and listed in the Xaccess file.
Affected Products:
- Caldera OpenLinux 2.3.0
- Debian Linux 2.2.0
- KDE KDE 1.1.0
- KDE KDE 1.1.1
- KDE KDE 1.1.2
- KDE KDE 1.2.0
- KDE KDE 2.0.0 BETA
- MandrakeSoft Linux Mandrake 7.0.0
- RedHat Linux 6.2.0
- RedHat Linux 7.0.0
- RedHat Linux 7.1.0
- Wings wdm 1.2.0
- XFree86 X11R6 3.3.3
- XFree86 X11R6 3.3.4
- XFree86 X11R6 3.3.5
- XFree86 X11R6 3.3.6
- XFree86 X11R6 4.0.0
- XFree86 X11R6 4.0.1
- XFree86 X11R6 4.0.3
References:
- XFree86: XFree86 Homepage
Juniper Networks provides this content via a wide variety of sources and production methods. If notified of errors or omissions in the content of this page, Juniper Networks, at its discretion, will modify or remove the page or leave the content as is, depending on various factors including but not limited to the reputation and authority of the party providing the notification. Please use the contact information displayed elsewhere on this page to report any errors or omissions regarding the content on this page.
