ISC Bind 4 nslookupComplain() Buffer Overflow Vulnerability



Date Discovered

January 29, 2001


BIND is a server program that implements the domain name service protocol. It is in extremely wide use on the Internet, in use by most of the DNS servers. Version 4 of BIND contains a stack overflow that may be exploitable to remote attackers. The vulnerability is due to unsafe use of the sprintf() function to construct an error message. If an attacker controls a DNS server, this vulnerability can be exploited. An attacker may be able to execute shellcode with the privileges of named (typically root).

Technologies Affected

  • ISC BIND 4.9.0
  • ISC BIND 4.9.3
  • ISC BIND 4.9.4
  • ISC BIND 4.9.5
  • ISC BIND 4.9.5 P1
  • ISC BIND 4.9.6
  • ISC BIND 4.9.7 -T1B
  • ISC BIND 4.9.7
  • ISC BIND 8.2.0


Block external access at the network boundary, unless external parties require service.
If the service is not required to be globally accessible it is recommended that access be restricted to trusted hosts and networks.

The ISC strongly recommends upgrading to BIND version 9.1.0. Links to download are available below. Sun has released Sun Alert (ID 26965) dealing with this and other issues. Please see the referenced advisory for more information. Additional fixes are also available.



Discovered and documented by Anthony Osborne and John McDonald of the COVERT Labs at PGP Security.

© 1995- Symantec Corporation

Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Security Response. Reprinting the whole or part of this alert in any medium other than electronically requires permission from


The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.

Symantec, Symantec products, Symantec Security Response, and are registered trademarks of Symantec Corp. and/or affiliated companies in the United States and other countries. All other registered and unregistered trademarks represented in this document are the sole property of their respective companies/owners.