Public Vulnerability Reports

Multiple Vendor Ethereal srvloc Buffer Overflow Vulnerability



Ethereal is a full featured open source network protocol analyzer. For
more information, see


Remote exploitation of a buffer overflow vulnerability in the Service
Location Protocol (srvloc) dissectors within Ethereal, as included in
various vendors' operating system distributions, could allow attackers
to crash the vulnerable process or execute arbitrary code.

The vulnerable code follows:


static guint8*
unicode_to_bytes(tvbuff_t *tvb, int offset, int length, gboolean endianness)
  const char    *ascii_text = tvb_get_ptr(tvb, offset, length);
  int   i, j=0;
  guint8        c_char, c_char1;
  static guint8 byte_array[255];

  if (endianness) {
      for (i = 0; i < length; i++) {
        c_char = ascii_text[i];
        if (c_char != 0) {
            byte_array[j] = c_char;

  return byte_array;

This function is called with a user-controlled length value on line 581
in the same file. This allows an attacker to cause an overflow of the
byte_array array, as values greater than 255 may be specified. In lab
analysis, it has been demonstrated that there are several interesting
values beyond this array that make arbitrary code execution possible.

To cause Ethereal to dissect an arbitrary packet with the srvloc
dissector, the source or destination port must be set to TCP port 427,
and the destination port must not be a port with any registered
dissector. As Ethereal does not keep state, a single spoofed TCP data
packet can be used to exploit this vulnerability, regardless of whether
there are any ports listening on either end.


Exploitation could result in remote root access, as Ethereal must have
root privileges to open a raw socket.

Ethereal is often used by network administrators to debug network
problems and compromise of a network administrators machine can lead to
further compromise of the network.


Ethereal versions 0.10.12 and earlier are reportedly vulnerable. The
following vendors include susceptible Ethereal packages within their
respective operating system distributions:

 The Debian Project: Debian GNU/Linux 3.0
 The FreeBSD Project: FreeBSD 5.4 and earlier
 Gentoo Foundation Inc.: Gentoo Linux 2004.0, 2004.1, 2004.2, 2004.3
   and 2005.0
 Mandriva SA: Mandriva Linux 10.1, 10.1 (x86_64),
   LE2005 and LE2005 (x86_64)
 Novell Inc.: SUSE Linux versions 9.0, 9.1, 9.2 and 9.3
 Red Hat Inc.: Fedora Core 3 and 4
    Red Hat Desktop (v. 3) Red Hat Desktop (v. 4)
    Red Hat Enterprise Linux AS (v. 2.1)
    Red Hat Enterprise Linux AS (v. 3)
    Red Hat Enterprise Linux AS (v. 4)
    Red Hat Enterprise Linux ES (v. 2.1)
    Red Hat Enterprise Linux ES (v. 3)
    Red Hat Enterprise Linux ES (v. 4)
    Red Hat Enterprise Linux WS (v. 2.1)
    Red Hat Enterprise Linux WS (v. 3)
    Red Hat Enterprise Linux WS (v. 4)
    Red Hat Linux Advanced Workstation 2.1 for the Itanium Processor


When using Ethereal, use the following filter to disable port 427, and
therefore, automatic srvloc dissection:

 not port 427


The vendor has addressed this issue in ethereal 0.10.13, available for
download at:


The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-3184 to this issue. This is a candidate for inclusion in
the CVE list (, which standardizes names for
security problems.


10/12/2005   Initial vendor notification
10/12/2005   Initial vendor response
10/20/2005   Coordinated public disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2005 Verisign, Inc.

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