TO UNSUBSCRIBE: email "unsubscribe alert" in the body of your message to majordomo@iss.net Contact alert-owner@iss.net for help with any problems! --------------------------------------------------------------------------- -----BEGIN PGP SIGNED MESSAGE----- Internet Security Systems Security Alert January 29, 2001 Remote Vulnerabilities in BIND versions 4 and 8 Synopsis: ISS X-Force is aware of several vulnerabilities in current versions of Internet Software Consortiums Berkeley Internet Name Domain (BIND). There is a buffer overflow present in BIND version 8 that an attacker could use to remotely execute arbitrary code. Version 4 of BIND contains three vulnerabilities, a buffer overflow and a format string vulnerability, both of which allow a remote attacker to execute arbitrary code, and a vulnerability which can expose the environment variables of the BIND server. BIND is the most popular implementation of the Domain Name Service (DNS) protocol. DNS is the Internet protocol that converts host and domain names into their corresponding IP addresses and vice-versa. Description: ISC BIND 8 Buffer Overflow in Transaction Signature (TSIG) Handling Code: BIND 8 contains a vulnerability that may allow a remote attacker to compromise any server with a vulnerable version of BIND installed. The vulnerability is present in Transaction Signatures (TSIG) functionality. Most current versions up to version 9.x are vulnerable. It is not necessary for the remote attacker to control an authoritative DNS server to the target to exploit this vulnerability. Both recursive and non-recursive servers are vulnerable. ISC BIND 4 Buffer Overflow in nslookupComplain(): A vulnerability exists in BIND 4 which under very specific circumstances may allow remote attackers to compromise servers running vulnerable versions of BIND 4. A buffer overflow condition in the nslookupComplain() function may be exploited to grant access to remote users. The attacker must have control of the targets authoritative nameserver to successfully exploit this vulnerability. ISC BIND 4 Input Validation Error in nslookupComplain(): The second vulnerability present in BIND 4 is present in the nslookupComplain() function as well. A user-supplied format string may be manipulated to run arbitrary code. The attacker must have control of the targets authoritative nameserver to successfully exploit this vulnerability. ISC BIND 4 Exposure of Environment Variables: This vulnerability may allow a remote attacker to expose variables within the BIND server. By sending a malformed query to vulnerable BIND servers, a remote attacker can gain access to the program stack. Additional limitations to successful exploitation of this vulnerability include the use of a limited character set when constructing the overflow string, as well as dynamic conditions such as the layout and allocation of memory for the BIND process. Affected Systems: ISC BIND version 8: 8.2, 8.2.1 8.2.2 through 8.2.2-P7 8.2.3-T1A through 8.2.3-T9B ISC Bind version 4: 4.9.3 through 4.9.7 Recommendations: It is recommended that all DNS administrators using BIND 4.9.x upgrade to BIND 4.9.8 and those using BIND 8.2.x upgrade to BIND 8.2.3. These upgrades may be found at: ftp://ftp.isc.org/isc/BIND/src/. DNS administrators should take precautions to limit the affects of permissions on their DNS server installations. The DNS server should never be executed with super-user privileges, and should also be sandboxed under a chroot environment. Please refer to the following URL for information on the use of chroot in order to provide an additional layer of security for exposed services: http://securityportal.com/cover/coverstory20001002.html ISS SAFEsuite intrusion detection system, RealSecure, and network security assessment product, Internet Scanner, will have signatures available to detect these vulnerabilities in the next X-Press Updates. Credits and References: CERT Advisory CA-201-02 Multiple Vulnerabities in BIND http://www.cert.org/advisories/CA-2001-02.html Network Associates Advisory http://www.pgp.com/research/covert/advisories.asp Internet Software Consortium http://www.isc.org/products/BIND/bind-security.html New BIND 4 and BIND 8 releases ftp://ftp.isc.org/isc/bind/src/ BIND 9.1 ftp://ftp.isc.org/isc/bind9/ About Internet Security Systems (ISS) Internet Security Systems (ISS) is a leading global provider of security management solutions for the Internet. By providing industry-leading SAFEsuite security software, remote managed security services, and strategic consulting and education offerings, ISS is a trusted security provider to its customers, protecting digital assets and ensuring safe and uninterrupted e-business. ISS' security management solutions protect more than 5,500 customers worldwide including 21 of the 25 largest U.S. commercial banks, 10 of the largest telecommunications companies and over 35 government agencies. Founded in 1994, ISS is headquartered in Atlanta, GA, with additional offices throughout North America and international operations in Asia, Australia, Europe, Latin America and the Middle East. For more information, visit the Internet Security Systems web site at www.iss.net or call 888-901-7477. Copyright (c) 2001 Internet Security Systems, Inc. Permission is hereby granted for the redistribution of this Alert electronically. It is not to be edited in any way without express consent of the X-Force. If you wish to reprint the whole or any part of this Alert in any other medium excluding electronic medium, please e-mail xforce@iss.net for permission. Disclaimer The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties with regard to this information. In no event shall the author be liable for any damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk. X-Force PGP Key available at: http://xforce.iss.net/sensitive.php as well as on MIT's PGP key server and PGP.com's key server. Please send suggestions, updates, and comments to: X-Force mailto:xforce@iss.net of Internet Security Systems, Inc. -----BEGIN PGP SIGNATURE----- Version: 2.6.3a Charset: noconv iQCVAwUBOnZEVTRfJiV99eG9AQEwywQAqQj3F7zunJeS4djHN1WupR86EmYK5Tt6 BEHdY6kz4CCS/A5Jeq90wD/3LDjs0PlwqaHa59Nktwjpret6tAQiOeOi6gz5Zw4H roFCwkcK9uEdv1DTVa4qgfB2levWFEsM1pCFFt/j2HLcRHWU7/S0AzVJOWBrOi3s WlMhus0ftUo= =clax -----END PGP SIGNATURE-----