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Category:   Application (Generic)  >   Tcpdump Vendors:
(Advisory is Available) Tcpdump Boundary Checking Error in 'print-isakmp.c' Lets Remote Users Crash Tcpdump
SecurityTracker Alert ID:  1009596
SecurityTracker URL:
CVE Reference:   CVE-2004-0183, CVE-2004-0184   (Links to External Site)
Date:  Mar 30 2004
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  Exploit Included:  Yes  
Version(s): prior to 3.8.2
Description:   Two vulnerabilities were reported in tcpdump. A remote user can cause tcpdump to crash when in a certain configuration.

The tcpdump vendor reported that 'print-isakmp.c' does not properly validate user-supplied input in ISAKMP packets. A remote user can send a specially crafted packet to trigger the flaw.

Rapid7 subsequently issued an advisory [see the Message History] that provided additional details. The advisory indicated that the vulnerability applies only in the verbose packet display (-v) mode.

A remote user can send a specially crafted ISAKMP Delete payload with a large number of Security Protocol Identifiers (SPIs) to cause the tcpdump application to crash [CVE: CVE-2004-0183] due to a buffer overflow.

It is also reported that a remote user can send an ISAKMP Identification payload with a specially crafted payload length value that is less than 8 to cause tcpdump to crash [CVE: CVE-2004-0184].

These vulnerabilities were discovered using Rapid7's Striker ISAKMP Protocol Test Suite. The Rapid7 advisory provides additional details and is available in the Source Message and at:

Impact:   A remote user can cause tcpdump to crash.
Solution:   The vendor has released a fixed version (3.8.3), available at:

[Editor's note: The vendor states that version 3.8.3 is identical to 3.8.2, but the version number was incremented to match the libpcap version number.]

Vendor URL: (Links to External Site)
Cause:   Boundary error
Underlying OS:  Linux (Any), UNIX (Any)

Message History:   This archive entry is a follow-up to the message listed below.
Mar 30 2004 Tcpdump Boundary Checking Error in 'print-isakmp.c' Lets Remote Users Crash Tcpdump

 Source Message Contents

Subject:  R7-0017: TCPDUMP ISAKMP payload handling denial-of-service vulnerabilities

Hash: SHA1

                     Rapid7, Inc. Security Advisory
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Rapid7 Advisory R7-0017
TCPDUMP ISAKMP payload handling denial-of-service vulnerabilities

   Published:  March 30, 2004
   Revision:   1.0

   CVE:    CAN-2004-0183, CAN-2004-0184

1. Affected system(s):

    o TCPDUMP v3.8.1 and earlier versions

2. Summary

   TCPDUMP v3.8.1 and earlier versions contain multiple flaws in the
   packet display functions for the ISAKMP protocol.  Upon receiving
   specially crafted ISAKMP packets, TCPDUMP will try to read beyond
   the end of the packet capture buffer and crash.

3. Vendor status and information


   The vendor was notified and they have released an updated version
   of TCPDUMP, version 3.8.2, which fixes these defects.  Subsequently,
   the version number was bumped to 3.8.3 to match libpcap.

4. Solution

   Upgrade to version 3.8.3 of TCPDUMP.  You should also consider
   upgrading to version 0.8.3 of libpcap.  Note that many vendors
   package their own customized version of TCPDUMP and libpcap with
   their operating system distribution.  You may want to consider
   contacting your operating system vendor for an upgrade.

5. Detailed analysis

   To test the security and robustness of IPSEC implementations
   from multiple vendors, the security research team at Rapid7
   has designed the Striker ISAKMP Protocol Test Suite.  Striker
   is an ISAKMP packet generation tool that automatically produces
   and sends invalid and/or atypical ISAKMP packets.

   This advisory is the second in a series of vulnerability
   disclosures discovered with the Striker test suite.  Striker
   will be made available to qualified IPSEC vendors.  Please
   email for more information on obtaining

   There are two defects in the ISAKMP packet display functions in
   TCPDUMP.  Both of them require that verbose packet display be
   enabled with the -v option.  These defects result in out-of-bounds

   Overflow in ISAKMP Delete payload with large number of SPI's
   CVE ID: CAN-2004-0183

      When displaying Delete payloads, TCPDUMP does not verify
      that (NSPIS * SPISIZE) fits within the snap buffer.

      An ISAKMP packet with a malformed Delete payload having
      a large self-reported number of SPI's will cause TCPDUMP
      to crash as it tries to read from beyond the end of the
      snap buffer.

      See section 3.15 of RFC 2408 for information on the
      Delete payload format.

   Integer underflow in ISAKMP Identification payload 
   CVE ID: CAN-2004-0184

      An ISAKMP packet with a malformed Identification payload
      with a self-reported payload length that becomes less than
      8 when its byte order is reversed will cause TCPDUMP to
      crash as it tries to read from beyond the end of the
      snap buffer.  TCPDUMP must be using a snaplen of 325 or
      greater for this underflow to be triggered.

      This is due to an inconsistency in the byte order conversion
      in the isakmp_id_print() function:

         if (sizeof(*p) < id.h.len)
            data = (u_char *)(p + 1);
            data = NULL;
         len = ntohs(id.h.len) - sizeof(*p);

      If id.h.len is equal to, say, 256 (and this fits within the snap
      buffer), then len will be equal to:

         ntohs(256) - sizeof(*p)

      which becomes a negative value on i386.

6. Contact Information

   Rapid7 Security Advisories
   Phone:  +1 (617) 603-0700

7. Disclaimer and Copyright

   Rapid7, LLC is not responsible for the misuse of the information
   provided in our security advisories.  These advisories are a service
   to the professional security community.  There are NO WARRANTIES
   with regard to this information.  Any application or distribution of
   this information constitutes acceptance AS IS, at the user's own
   risk.  This information is subject to change without notice.

   This advisory Copyright (C) 2004 Rapid7, LLC.  Permission is
   hereby granted to redistribute this advisory, providing that no
   changes are made and that the copyright notices and disclaimers
   remain intact.
Version: GnuPG v1.2.2 (OpenBSD)



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