Multiple Vendor Kerberos kadmind Buffer Overflow Vulnerability
iDefense Security Advisory 04.03.07 http://labs.idefense.com/intelligence/vulnerabilities/ Apr 03, 2007
Kerberos is a network authentication protocol. It is used in client-server systems to provide user authentication by using a ticket based system. kadmind is the Kerberos administration server. It is used to configure principals and policies on the Kerberos. More information can be found on the vendor's website at the following URL.
Remote exploitation of a buffer overflow vulnerability in the Kerberos kadmind server, as included in various vendors' operating system distributions, could allow attackers to execute arbitrary code on a targeted host.
The vulnerability exists within the server's logging function, klog_vsyslog(). A call is made to vsprintf(), with the destination buffer passed as a fixed size stack buffer. User input is not properly validated before being passed to this function, and a stack based buffer overflow can occur.
Exploitation allows an attacker to execute arbitrary code with root privileges on the targeted host.
In order to exploit this vulnerability, an attacker must have valid credentials stored on the server. Administrator privileges are not necessary. The kadmind server runs on the master Kerberos server. Since the master server holds the KDC principal and policy database, a compromise could lead to a compromise of multiple hosts that use the server for authentication.
iDefense has confirmed the existence of this vulnerability with Kerberos version 1.5.1 on Fedora CORE 5. It is likely that all distributions that contain this version of Kerberos are vulnerable.
iDefense is currently unaware of any workarounds for this issue.
VI. VENDOR RESPONSE
The MIT Kerberos team has made patches available to address this vulnerability. For more information consult their advisory at the following URL.
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-0957 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.
VIII. DISCLOSURE TIMELINE
02/08/2007 Initial vendor notification 02/08/2007 Initial vendor response 04/03/2007 Coordinated public disclosure
The discoverer of this vulnerability wishes to remain anonymous.
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X. LEGAL NOTICES
Copyright © 2007 iDefense, Inc.
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