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TUCoPS :: Unix :: General :: ciacl015.htm

Tcpdump Remote Buffer Overflows



Tcpdump Remote Buffer Overflows Privacy and Legal Notice

CIAC INFORMATION BULLETIN

L-015: Tcpdump Remote Buffer Overflows

October 31, 2000 13:00 GMT
PROBLEM:       Tcpdump version 3.5 contains remote buffer overflows that
               results in tcpdump crashing or allowing the remote attacker to
               execute arbitrary code as root.
PLATFORM:      Linux and BSD operating systems
DAMAGE:        A remote user will be able to gain root or crash some Intrusion
               Detection systems.
SOLUTION:      Upgrade to the latest version of tcpdump, 3.5.2.

VULNERABILITY The risk is HIGH. Expolit code is not publically available, ASSESSMENT: but the application is common to many default OS installs.
Background Tcpdump is a free sniffer developed first by Lawrence Berkeley National Laboratory, and now is maintained by a consortium. It is most commonly used to capture ethernet packets in a common format that many analysis tools can read. It is the basis for many Intrusion Detection Software applications. It is now bundled with many linux and BSD type operating systems and is sometimes installed with the default installation package. Issue During internal source code auditing done by FreeBSD, several overflowable buffers were discovered in the version of tcpdump included in many OS'. Some simply allow the remote attacker to crash the local tcpdump process. This is a problem for systems using tcpdump as a form of intrusion detection, as after an attacker has crashed the tcpdump process, network activity will no longer occur. There is a more serious vulnerability in the decoding of AFS ACL packets in the more recent version of tcpdump (tcpdump 3.5) which may allow a remote attacker to execute arbitrary code on the local system (usually at root privilege, since root privilege is required to run tcpdump). Fix Do not use vulnerable versions of tcpdump. Upgrade to the most recent version of the application (3.5.2) from www.tcpdump.org, or consult you OS vendor for a fix. For example, for FreeBSD: a) FreeBSD 3.x systems prior to the correction date Download the patch and the detached PGP signature from the following locations, and verify the signature using your PGP utility. ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-00:61/tcpdump-3.x.patch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-00:61/tcpdump-3.x.patch.asc # cd /usr/src/contrib/tcpdump # patch -p < /path/to/patch # cd /usr/src/usr.sbin/tcpdump # make depend && make all install b) FreeBSD 4.x systems prior to the correction date Download the patch and the detached PGP signature from the following locations, and verify the signature using your PGP utility. ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-00:61/tcpdump-4.x.patch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-00:61/tcpdump-4.x.patch.asc # cd /usr/src/contrib/tcpdump # patch -p < /path/to/patch # cd /usr/src/usr.sbin/tcpdump # make depend && make all install

CIAC wishes to acknowledge the contributions of FreeBSD for information contained in this bulletin.
CIAC services are available to DOE, DOE Contractors, and the NIH. CIAC can be contacted at:
    Voice:          +1 925-422-8193 (7 x 24)
    FAX:            +1 925-423-8002
    STU-III:        +1 925-423-2604
    E-mail:          ciac@llnl.gov
    World Wide Web:  http://www.ciac.org/
                     http://ciac.llnl.gov
                     (same machine -- either one will work)
    Anonymous FTP:   ftp.ciac.org
                     ciac.llnl.gov
                     (same machine -- either one will work)

This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes.
UCRL-MI-119788
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