Published:
19 August 1999
Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-1999.119 -- RHSA-1999:029-01 Denial of service attack in in.telnetd 20 August 1999 =========================================================================== Red Hat Software, Inc. has released the following advisory addressing a denial of service vulnerability in the remote login daemon in.telnetd. - --------------------------BEGIN INCLUDED TEXT-------------------- - --------------------------------------------------------------------- Red Hat, Inc. Security Advisory Synopsis: Denial of service attack in in.telnetd Advisory ID: RHSA-1999:029-01 Issue date: 1999-08-19 Updated on: Keywords: telnet telnetd Cross references: - --------------------------------------------------------------------- 1. Topic: A denial of service attack has been fixed in in.telnetd. 2. Bug IDs fixed (http://developer.redhat.com/bugzilla/): 4560 3. Relevant releases/architectures: Red Hat Linux 4.2, 5.2, 6.0, all architectures 4. Obsoleted by: 5. Conflicts with: 6. RPMs required: Red Hat Linux 4.2: Intel: ftp://ftp.redhat.com/redhat/updates/4.2/i386/NetKit-B-0.09-11.i386.rpm Alpha: ftp://ftp.redhat.com/redhat/updates/4.2/alpha/NetKit-B-0.09-11.alpha.rpm Sparc: ftp://ftp.redhat.com/redhat/updates/4.2/sparc/NetKit-B-0.09-11.sparc.rpm Source packages: ftp://ftp.redhat.com/redhat/updates/4.2/SRPMS/NetKit-B-0.09-11.src.rpm Red Hat Linux 5.2: Intel: ftp://ftp.redhat.com/redhat/updates/5.2/i386/telnet-0.10-28.5.2.i386.rpm Alpha: ftp://ftp.redhat.com/redhat/updates/5.2/alpha/telnet-0.10-28.5.2.alpha.rpm Sparc: ftp://ftp.redhat.com/redhat/updates/5.2/sparc/telnet-0.10-28.5.2.sparc.rpm Source packages: ftp://ftp.redhat.com/redhat/updates/5.2/SRPMS/telnet-0.10-28.5.2.src.rpm Red Hat Linux 6.0: Intel: ftp://ftp.redhat.com/redhat/updates/6.0/i386/telnet-0.10-29.i386.rpm Alpha: ftp://ftp.redhat.com/redhat/updates/6.0/alpha/telnet-0.10-29.alpha.rpm Sparc: ftp://ftp.redhat.com/redhat/updates/6.0/sparc/telnet-0.10-29.sparc.rpm Source packages: ftp://ftp.redhat.com/redhat/updates/6.0/SRPMS/telnet-0.10-29.src.rpm 7. Problem description: in.telnetd attempts to negotiate a compatible terminal type between the local and remote host. By setting the TERM environment variable before connecting, a remote user could cause the system telnetd to open files it should not. Depending on the TERM setting used, this could lead to denial of service attacks. Thanks go to Michal Zalewski and the Linux Security Audit team for noting this vulnerability. 8. Solution: For each RPM for your particular architecture, run: rpm -Uvh <filename> where filename is the name of the RPM. 9. Verification: MD5 sum Package Name - -------------------------------------------------------------------------- 0c425c34fb77a8309ff10b4143e9b847 i386/NetKit-B-0.09-11.i386.rpm d791d645adeb5fa0147c1058b21cbbac alpha/NetKit-B-0.09-11.alpha.rpm bfbd440845191bbdcf8be21ee59bf6a8 sparc/NetKit-B-0.09-11.sparc.rpm ccd5ab53c423e468d66ca801c90b5ae4 SRPMS/NetKit-B-0.09-11.src.rpm ef33f3c5ca810d05420e57b5cfcf8928 i386/telnet-0.10-28.5.2.i386.rpm 6dc23437a200193b0bfed23d5f5e6562 alpha/telnet-0.10-28.5.2.alpha.rpm 49c38457cc0a82a680fd9b9634dc8021 sparc/telnet-0.10-28.5.2.sparc.rpm 2f33670a683e3abef0e4914586c71961 SRPMS/telnet-0.10-28.5.2.src.rpm 4360d47490f13d60b8737d28dc88825a i386/telnet-0.10-29.i386.rpm 90213fcdca41a3ed12ab7d92344e7286 alpha/telnet-0.10-29.alpha.rpm 277787dbc39dff8ea84d4b16dcb7a954 sparc/telnet-0.10-29.sparc.rpm 269783a0754d234f7bef0f4717a8dbc2 SRPMS/telnet-0.10-29.src.rpm These packages are PGP signed by Red Hat Inc. for security. Our key is available at: http://www.redhat.com/corp/contact.html You can verify each package with the following command: rpm --checksig <filename> If you only wish to verify that each package has not been corrupted or tampered with, examine only the md5sum with the following command: rpm --checksig --nopgp <filename> 10. References: - --------------------------END INCLUDED TEXT-------------------- This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to use any or all of this information is the responsibility of each user or organisation, and should be done so in accordance with site policies and procedures. NOTE: This is only the original release of the security bulletin. It will not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the original authors to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/Information/advisories.html If you believe that your system has been compromised, contact AusCERT or your representative in FIRST (Forum of Incident Response and Security Teams). Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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