[Full-disclosure] iDEFENSE Security Advisory 10.20.05: Multiple Vendor Ethereal srvloc Buffer Overflow Vulnerability

Type securityvulns
Reporter Securityvulns
Modified 2005-10-21T00:00:00


Multiple Vendor Ethereal srvloc Buffer Overflow Vulnerability

iDEFENSE Security Advisory 10.20.05 www.idefense.com/application/poi/display?id=323&type=vulnerabilities October 20, 2005


Ethereal is a full featured open source network protocol analyzer. For more information, see http://www.ethereal.com/


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

byte_array[j]=0; 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 (http://cve.mitre.org), 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 (c) 2005 iDEFENSE, Inc.

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Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.

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