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FreeBSD-SA-05:01.telnet Security Advisory The FreeBSD Project Topic: telnet client buffer overflows Category: contrib Module: contrib/telnet Announced: 2005-03-28 Credits: iDEFENSE Affects: All FreeBSD releases prior to 5.4-RELEASE Corrected: 2005-03-28 15:50:00 UTC (RELENG_5, 5.4-PRERELEASE) 2005-03-28 15:48:00 UTC (RELENG_4, 4.11-STABLE) 2005-03-28 15:52:00 UTC (RELENG_5_3, 5.3-RELEASE-p6) 2005-03-28 15:57:00 UTC (RELENG_4_11, 4.11-RELEASE-p1) 2005-03-28 15:58:00 UTC (RELENG_4_10, 4.10-RELEASE-p6) 2005-03-28 16:00:00 UTC (RELENG_4_8, 4.8-RELEASE-p28) CVE Name: CAN-2005-0468 CAN-2005-0469 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://www.freebsd.org/security/>. I. Background The telnet(1) command is a TELNET protocol client, used primarily to establish terminal sessions across a network. II. Problem Description Buffer overflows were discovered in the env_opt_add() and slc_add_reply() functions of the telnet(1) command. TELNET protocol commands, options, and data are copied from the network to a fixed-sized buffer. In the case of env_opt_add (CAN-2005-0468), the buffer is located on the heap. In the case of slc_add_reply (CAN-2005-0469), the buffer is global uninitialized data (BSS). III. Impact These buffer overflows may be triggered when connecting to a malicious server, or by an active attacker in the network path between the client and server. Specially crafted TELNET command sequences may cause the execution of arbitrary code with the privileges of the user invoking telnet(1). IV. Workaround Do not use telnet(1) to connect to untrusted machines or over an untrusted network. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the RELENG_5_3, RELENG_4_11, RELENG_4_10, or RELENG_4_8 security branch dated after the correction date. 2) To patch your present system: The following patches have been verified to apply to FreeBSD 4.8, 4.10, 4.11, and 5.3 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 4.x] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:01/telnet4.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:01/telnet4.patch.asc [FreeBSD 5.x] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:01/telnet5.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:01/telnet5.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Rebuild the operating system as described in <URL:http://www.freebsd.org/doc/handbook/makeworld.html>. VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. Branch Revision Path ------------------------------------------------------------------------- RELENG_4 src/crypto/heimdal/appl/telnet/telnet/telnet.c 1.1.1.1.2.4 src/crypto/kerberosIV/appl/telnet/telnet/telnet.c 1.1.1.1.2.1 src/crypto/telnet/telnet/telnet.c 1.4.2.6 src/usr.bin/telnet/telnet.c 1.8.2.4 RELENG_4_11 src/UPDATING 1.73.2.91.2.2 src/crypto/heimdal/appl/telnet/telnet/telnet.c 1.1.1.1.2.3.10.1 src/crypto/kerberosIV/appl/telnet/telnet/telnet.c 1.1.1.1.22.1 src/crypto/telnet/telnet/telnet.c 1.4.2.5.12.1 src/sys/conf/newvers.sh 1.44.2.39.2.5 src/usr.bin/telnet/telnet.c 1.8.2.3.12.1 RELENG_4_10 src/UPDATING 1.73.2.90.2.7 src/crypto/heimdal/appl/telnet/telnet/telnet.c 1.1.1.1.2.3.8.1 src/crypto/kerberosIV/appl/telnet/telnet/telnet.c 1.1.1.1.20.1 src/crypto/telnet/telnet/telnet.c 1.4.2.5.10.1 src/sys/conf/newvers.sh 1.44.2.34.2.8 src/usr.bin/telnet/telnet.c 1.8.2.3.10.1 RELENG_4_8 src/UPDATING 1.73.2.80.2.32 src/crypto/heimdal/appl/telnet/telnet/telnet.c 1.1.1.1.2.3.4.1 src/crypto/kerberosIV/appl/telnet/telnet/telnet.c 1.1.1.1.16.1 src/crypto/telnet/telnet/telnet.c 1.4.2.5.6.1 src/sys/conf/newvers.sh 1.44.2.29.2.29 src/usr.bin/telnet/telnet.c 1.8.2.3.6.1 RELENG_5 src/contrib/telnet/telnet/telnet.c 1.14.6.1 RELENG_5_3 src/UPDATING 1.342.2.13.2.9 src/contrib/telnet/telnet/telnet.c 1.14.8.1 src/sys/conf/newvers.sh 1.62.2.15.2.11 ------------------------------------------------------------------------- VII. References [IDEF0866] Multiple Telnet Client slc_add_reply() Buffer Overflow http://www.idefense.com/application/poi/display?id=220&type=vulnerabilities [IDEF0867] Multiple Telnet Client env_opt_add() Buffer Overflow http://www.idefense.com/application/poi/display?id=221&type=vulnerabilities
debian devs solved this one in http://security.debian.org/pool/updates/main/n/netkit-telnet/netkit-telnet_0.17-18woody3.diff.gz I guess netkit-telnet is also vulnerable...
netkit-telnetd 0.17-r4 uses Debian patchset 26 so it's unaffected.
I think I remember some people in #-dev saying vapier maintains this (much to their relief)
Created an attachment (id=54831) [details] telnet-bsd-1.0 security patch Hi folks, I talked to jaervoz on IRC and said that I would try/port freebsd's patch for this package. FreeBSD's patch isn't suitable because freebsd's telnet.c has some functions in different lines than linux one. Hope it helps.
1.0-r1 now in portage
Thx everyone. This one is ready for GLSA.
GLSA 200504-01
