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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2001.028 -- FreeBSD-SA-01:05.stunnel stunnel contains potential remote compromise 22 January 2001 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: stunnel Vendor: FreeBSD Ports Collection Operating System: FreeBSD BSD Unix Impact: Root Compromise Access Required: Remote - - --------------------------BEGIN INCLUDED TEXT-------------------- - - -----BEGIN PGP SIGNED MESSAGE----- ============================================================================= FreeBSD-SA-01:05 Security Advisory FreeBSD, Inc. Topic: stunnel contains potential remote compromise Category: ports Module: stunnel Announced: 2001-01-15 Credits: Lez <lez@SCH.BME.HU>, Brian Hatch <bri@STUNNEL.ORG> Affects: Ports collection prior to the correction date. Corrected: 2000-12-20 Vendor status: Updated version released FreeBSD only: NO I. Background stunnel is an SSL encryption wrapper for network services. II. Problem Description The stunnel port, versions prior to 3.9, contains a vulnerability which could allow remote compromise. When debugging is turned on (using the -d 7 option), stunnel will perform identd queries of remote connections, and the username returned by the remote identd server is written to the log file. Due to incorrect usage of syslog(), a malicious remote user who can manipulate their identd username can take advantage of string-formatting operators to execute arbitrary code on the local system as the user running stunnel, often the root user. The stunnel port is not installed by default, nor is it "part of FreeBSD" as such: it is part of the FreeBSD ports collection, which contains nearly 4500 third-party applications in a ready-to-install format. The ports collections shipped with FreeBSD 3.5.1 and 4.2 contain this problem since it was discovered after the releases. FreeBSD makes no claim about the security of these third-party applications, although an effort is underway to provide a security audit of the most security-critical ports. III. Impact Malicious remote users may execute arbitrary code on the local system as the user running stunnel using stunnel, under certain circumstances. If you have not chosen to install the stunnel port/package, then your system is not vulnerable to this problem. IV. Workaround Deinstall the stunnel port/package, if you have installed it. V. Solution One of the following: 1) Upgrade your entire ports collection and rebuild the stunnel port. 2) Deinstall the old package and install a new package dated after the correction date, obtained from: ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/security/stunnel-3.10.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/security/stunnel-3.10.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/security/stunnel-3.10.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/security/stunnel-3.10.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/security/stunnel-3.10.tgz 3) download a new port skeleton for the stunnel port from: http://www.freebsd.org/ports/ and use it to rebuild the port. 4) Use the portcheckout utility to automate option (3) above. The portcheckout port is available in /usr/ports/devel/portcheckout or the package can be obtained from: ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/devel/portcheckout-2.0.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/portcheckout-2.0.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/devel/portcheckout-2.0.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/devel/portcheckout-2.0.tgz - - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (FreeBSD) Comment: For info see http://www.gnupg.org iQCVAwUBOmN6T1UuHi5z0oilAQGFYwP/TLc1mxrH+2H7XhW/srJraZwtQn33z66t 1xASiaxefICPgnFvXHZoTMpkJI5ow2SFyLjUE2jG1MW2e5iu6fl7AeYIYNT1BF2t cqr6LRS92Srant5YbFqoBaTUuJtjw61T0P+dcjHfMCJAHVtihoQk8Ngw2YoX0KfV 5ReEYZPh530= =okQ9 - - -----END PGP SIGNATURE----- - - --------------------------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 may 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). On call after hours for emergencies. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBOm/y3yh9+71yA2DNAQFwfQQAnQgwW8VaRAV+zCFQ1WlI6fkKIA4ww4zS QGOAa92Is6PxvYE0DOIPRoxjJFxh/re9q5LK30v8F5fl8q6FgWOA4jDzYzmpNvwj UO6633k3s1zCnvWsIp/rLFv/addLF5okIX2YtPpIrSvG6wT9BIFNRULSxiSDhVzX HaP9pJtVPAs= =a6k2 -----END PGP SIGNATURE-----