Vulnerability Note VU#317350

ISC DHCP contains a stack buffer overflow vulnerability in handling log lines containing ASCII characters only

Overview

The Internet Systems Consortium's (ISC) Dynamic Host Configuration Protocol (DHCP) 3 application contains a buffer overflow vulnerability. Exploitation of this vulnerability can cause a denial of service condition to the DHCP Daemon (DHCPD) and may permit a remote attacker to execute arbitrary code on the system with the privileges of the DHCPD process.

I. Description

As described in RFC 2131, "the Dynamic Host Configuration Protocol (DHCP) provides a framework for passing configuration information to hosts on a TCP/IP network."

ISC DHCPD syslogs every DHCP packet in transactions along with several pieces of descriptive information. The client's DISCOVER and the resulting OFFER, REQUEST, and ACK are all logged as well as any NAKs. In all of these messages, if the client supplied a hostname then it is also included in the logged line. If the client supplies multiple hostname options these options will be concatenated together. If the hostname and options contain only ASCII characters, then the string will pass non-ASCII character filters and be temporarily stored in 1024 byte fixed-length buffers on the stack.

It is possible that if enough hostname options are supplied by the client, and other text is logged in the same line, then the static buffer will be overflown, writing over the stack. If non-ASCII or non-printable characters are supplied, then there are other checks and filters that will prevent this buffer overflow from occuring.

Only ISC DHCP 3.0.1rc12 and ISC DHCP 3.0.1rc13 are believed to be vulnerable for all operating systems and configurations. All versions of ISC DCHP 3, including all snapshots, betas, and release candidates, contain the flawed code. However, since these versions discard of all but the last hostname option provided by the client, it is not believed that these versions are exploitable.

II. Impact

A remote attacker with the ability to send a crafted packet to the DHCPD listening port (typically port 67/UDP), may be able to crash the ISC DHCP daemon, causing a denial of service. It may be possible to execute arbitrary code on the vulnerable server with the privileges of the DHCPD process (typically root).

III. Solution

ISC has released DHCP 3.0.1rc14 which resolves this issue. Versions prior to ISC DHCP 3 are no longer supported. All users of ISC DHCP are encouraged to update to the latest version.

Systems Affected

Vendor	Status	Date Updated
3Com	Unknown	22-Jun-2004
Alcatel	Unknown	22-Jun-2004
Apple Computer Inc.	Not Vulnerable	22-Jun-2004
Aruba Networks	Not Vulnerable	23-Jun-2004
AT&T	Unknown	22-Jun-2004
Avaya	Unknown	22-Jun-2004
Avici Systems Inc.	Unknown	22-Jun-2004
Charlotte's Web Networks	Unknown	22-Jun-2004
Check Point	Not Vulnerable	22-Jun-2004
Chiaro Networks	Not Vulnerable	22-Jun-2004
Cisco Systems Inc.	Not Vulnerable	24-Jun-2004
Conectiva	Unknown	22-Jun-2004
Cray Inc.	Unknown	22-Jun-2004
D-Link Systems	Unknown	22-Jun-2004
Data Connection	Unknown	22-Jun-2004
Debian	Unknown	22-Jun-2004
EMC Corporation	Unknown	22-Jun-2004
Engarde	Unknown	22-Jun-2004
Extreme Networks	Not Vulnerable	22-Jun-2004
F5 Networks	Not Vulnerable	22-Jun-2004
Fedora Project	Vulnerable	22-Jun-2004
Foundry Networks Inc.	Unknown	22-Jun-2004
FreeBSD	Unknown	22-Jun-2004
Fujitsu	Unknown	22-Jun-2004
Hewlett-Packard Company	Not Vulnerable	22-Jun-2004
Hitachi	Not Vulnerable	22-Jun-2004
Hyperchip	Unknown	22-Jun-2004
IBM	Not Vulnerable	22-Jun-2004
IBM-zSeries	Unknown	22-Jun-2004
IBM eServer	Unknown	22-Jun-2004
Immunix	Unknown	22-Jun-2004
InfoBlox	Vulnerable	13-Jul-2004
Ingrian Networks	Unknown	22-Jun-2004
Intel	Unknown	22-Jun-2004
ISC	Vulnerable	22-Jun-2004
Juniper Networks	Not Vulnerable	22-Jun-2004
Lucent Technologies	Unknown	22-Jun-2004
Luminous	Unknown	22-Jun-2004
MandrakeSoft	Vulnerable	23-Jun-2004
Microsoft Corporation	Not Vulnerable	23-Jun-2004
MontaVista Software	Unknown	22-Jun-2004
Multi-Tech Systems Inc.	Unknown	22-Jun-2004
Multinet	Unknown	22-Jun-2004
NEC Corporation	Unknown	22-Jun-2004
NetBSD	Not Vulnerable	22-Jun-2004
NetScreen	Unknown	22-Jun-2004
Network Appliance	Unknown	22-Jun-2004
NextHop	Unknown	22-Jun-2004
Nokia	Unknown	22-Jun-2004
Nominum	Not Vulnerable	24-Jun-2004
Nortel Networks	Unknown	22-Jun-2004
Novell	Unknown	22-Jun-2004
OpenBSD	Not Vulnerable	23-Jun-2004
Openwall GNU/*/Linux	Not Vulnerable	23-Jun-2004
Red Hat Inc.	Not Vulnerable	22-Jun-2004
Redback Networks Inc.	Not Vulnerable	22-Jun-2004
Riverstone Networks	Not Vulnerable	22-Jun-2004
SCO	Unknown	22-Jun-2004
Sequent	Unknown	22-Jun-2004
SGI	Unknown	22-Jun-2004
Sony Corporation	Unknown	22-Jun-2004
Sun Microsystems Inc.	Not Vulnerable	22-Jun-2004
SuSE Inc.	Vulnerable	23-Jun-2004
TurboLinux	Unknown	22-Jun-2004
Unisys	Unknown	22-Jun-2004
Wind River Systems Inc.	Unknown	22-Jun-2004
ZyXEL	Unknown	22-Jun-2004

References

Credit

Thanks to Gregory Duchemin and Solar Designer for discovering, reporting and resolving this vulnerability. Thanks also to David Hankins of ISC for notifying us of this vulnerability and the technical information provided to create this document.

This document was created by Jason A Rafail and based on the technical information provided by David Hankins of ISC.

Other Information

Date Public	06/22/2004
Date First Published	06/22/2004 02:11:27 PM
Date Last Updated	07/13/2004
CERT Advisory
CVE Name	CAN-2004-0460
US-CERT Technical Alerts
Metric	25.51
Document Revision	16

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