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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2000.404 -- NetBSD Security Advisory 2000-018 One-byte buffer overrun in ftpd 22 December 2000 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: ftpd Vendor: NetBSD Operating System: NetBSD OpenBSD Impact: Root Compromise Access Required: Remote Ref: ESB-2000.402 - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- NetBSD Security Advisory 2000-018 ================================= Topic: One-byte buffer overrun in ftpd Version: All official releases up to and including 1.5 Severity: possible remote root compromise. Fixed: NetBSD-current: December 4, 2000 NetBSD 1.4 branch: December 14, 2000 NetBSD 1.5 branch: December 13, 2000 Abstract ======== A one-byte buffer overrun was found in the ftp server daemon (/usr/libexec/ftpd). It is rumored to be remotely exploitable. Systems running ftpd are vulnerable. ftpd is usually started from inetd; inetd is configured through the /etc/inetd.conf file. As of the release date of this advisory, all of past NetBSD releases, including NetBSD 1.5, are vulnerable. Fresh installs of NetBSD 1.5 are not vulnerable as ftpd is disabled by default in /etc/inetd.conf; however, a system upgraded from an earlier release to 1.5 may still be using an old inetd.conf with ftpd still enabled, or it may need to run and ftp server and will thus have it enabled. Technical Details ================= The replydirname() function is used in ftpd to return pathname strings to the ftp client. It contained an erroneous bounds check. Solutions and Workarounds ========================= All NetBSD official releases up to 1.5, have a vulnerable ftp server binary in /usr/libexec/ftpd. We need to replace it to fix the problem. If you do not run ftpd on your system, you system is not vulnerable. Check /etc/inetd.conf to see if you have a line starts with "ftp". We suggest you to apply the fix anyways, in case you want to run ftpd in the future. Note that NetBSD 1.5 does not run ftpd by default (inetd.conf has a commented-out "ftp" line). Systems running NetBSD-current dated from before December 4, 2000 should be upgraded to NetBSD-current dated December 4, 2000 or later. Systems running releases older than NetBSD 1.4 should be upgraded to NetBSD 1.4.3 before applying the fixes described here. Systems running NetBSD 1.4.3 should apply the patch contained in ftp://ftp.NetBSD.ORG/pub/NetBSD/misc/security/patches/20001220-ftpd-1.4.3 Systems running NetBSD 1.5 should apply the patch contained in ftp://ftp.NetBSD.ORG/pub/NetBSD/misc/security/patches/20001220-ftpd-1.5 Different patches are needed because the vulnerable function was moved from ftpd.c to cmds.c. In the following examples, we assume that you have full source code under /usr/src, and have stored a copy of the patch in a file named "20001220-ftpd" in /usr/src/libexec/ftpd In either case, the patch should be applied in /usr/src/libexec/ftpd and ftpd should then be rebuilt and reinstalled using the following commands: # cd /usr/src/libexec/ftpd # patch < 20001220-ftpd # make cleandir # make depend # make # make install To be sure that the system is no longer vulnerable, you should ensure that all ftpd processes running on the system started after ftpd was reinstalled. Thanks To ========= Kristian Vlaardingerbroek <kris@obit.nl> Revision History ================ 2000/12/20 - Initial revision More Information ================ Information about NetBSD and NetBSD security can be found at http://www.NetBSD.ORG/ and http://www.NetBSD.ORG/Security/. Copyright 2000, The NetBSD Foundation, Inc. All Rights Reserved. $NetBSD: NetBSD-SA2000-018.txt,v 1.1 2000/12/20 18:46:53 sommerfeld Exp $ - -----BEGIN PGP SIGNATURE----- Version: 2.6.3ia Charset: noconv iQCVAwUBOkD+5z5Ru2/4N2IFAQFmPQP9E8ShVWoi69PDts+q3KmzyBWNORG4Vu0+ XzK6WP6HwRbHTD4Mj6Zcmv0Ds0He1OeiWi9b+mQ8XJZC/mIjdJLaGyZs/oB/yHhv MIKKh+vgsTmu+VW2SoxY45A2Y2Qkyoxanqmi206AsIQvr+q5TTH07V6guPUvgs1J kFsRDbE3OcE= =TS0t - -----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. 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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 iQCVAwUBOlSNdCh9+71yA2DNAQGg8AP/TB2py19Jiy1pG0H6MhKdplldCpg90Vcm 3WbnXMV3WgMtuKcfdxwlm9iunHHomh/AiksmAbQs/i1ibD/PuDCMFgdxUrKzPcA/ z0Z72+XCg1IHXY3YzwMWmlKccvQ7W/vhZT4aYSJPch8HTPmc1+FxO18LEnCD4qyy 649gB1RCmBM= =WCc5 -----END PGP SIGNATURE-----