Advisory EM03/2004: Multiple (13) Ethereal remote overflows



                           e-matters GmbH
www.e-matters.de

-= Security Advisory =-



Advisory: Multiple (13) Ethereal remote overflows
Release Date: 2004/03/23
Last Modified: 2004/03/23
Author: Stefan Esser [s.esser@hardened-php.net]

Application: Ethereal 0.8.14 - 0.10.2
Severity: 13 remotely triggerable vulnerabilities were
discovered in the multiprotocol packet sniffer
Ethereal that allow remote compromise
Risk: Critical
Vendor Status: Plans to release a fixed version within this week
Reference: http://security.e-matters.de/advisories/032004.html


Overview:

Quote from http://www.ethereal.com

"Ethereal is used by network professionals around the world for
troubleshooting, analysis, software and protocol development, and
education. It has all of the standard features you would expect in
a protocol analyzer, and several features not seen in any other
product. Its open source license allows talented experts in the
networking community to add enhancements. It runs on all popular
computing platforms, including Unix, Linux, and Windows."

During a code audit of Ethereal thirteen remotely triggerable stack-
overflows where discovered. The vulnerable dissectors in question
are namely: BGP, EIGRP, IGAP, IRDA, ISUP, NetFlow, PGM, TCAP and UCP.

With the exception of 3 all discovered overflows allow arbitrary code
execution by injecting carefully crafted packets to the sniffed wire
or by convincing someone to load a malicious packet capture file into
Ethereal.


Details:

In the beginning of March a code audit of Ethereal revealed remotely
triggerable overflows within a few of the over 400 dissectors. During
the process of working with the Ethereal vendor the audit continued
and until today it was possible to identify a total count of 13
possible stack overflows within 9 different dissectors.

For the purpose of clarity it was choosen to describe all these bugs
within this advisory instead of spreading the information over nine
single advisories.

Because the defects affect different parts of the code base and
were introduced at different dates within the last 3 years the
following table gives a short overview of the exact CVS commit
timestamps and the version number it first appeared in.

(Version 0.8.14)


[04] EIGRP Dissector TLV_IP_INT Long IP Address Overflow
- Revision: 1.7, Thu Nov 9 05:16:19 2000 UTC

[05] EIGRP Dissector TLV_IP_EXT Long IP Address Overflow
- Revision: 1.7, Thu Nov 9 05:16:19 2000 UTC


(version 0.8.19)

[06] PGM Dissector NakList Overflow
- Revision: 1.1, Thu Jul 12 20:16:28 2001 UTC


(version 0.9.0)

[11] UCP Dissector Handle String-Field Overflow
- Revision: 1.1, Mon Oct 8 17:30:23 2001 UTC

[12] UCP Dissector Handle Int-Field Overflow
- Revision: 1.1, Mon Oct 8 17:30:23 2001 UTC

[13] UCP Dissector Handle Time-Field Overflow
- Revision: 1.1, Mon Oct 8 17:30:23 2001 UTC


(version 0.9.10)

[01] Netflow v9 Dissector Template Caching Overflow
- Revision 1.9 Tue Mar 4 03:37:12 2003 UTC


(version 0.9.16)

[09] ISUP Dissector INTERWORKING FUNCTION ADDRESS Overflow
- Revision: 1.29, Fri Oct 3 20:58:13 2003 UTC

[10] TCAP Dissector TID Overflow
- Revision: 1.1, Thu Oct 2 06:13:28 2003 UTC


(version 0.10.0)

[02] IGAP Dissector Account Overflow
- Revision 1.1 Wed Dec 10 19:21:55 2003 UTC

[03] IGAP Dissector Message Overflow
- Revision 1.1 Wed Dec 10 19:21:55 2003 UTC


(version 0.10.1)

[08] BGP Dissector MPLS Label Overflow
- Revision: 1.84, Tue Jan 6 02:29:36 2004 UTC

[07] IRDA Dissector Plugin IRCOM_PORT_NAME Overflow
- Revision: 1.1, Thu Dec 18 19:07:12 2003 UTC



In the following paragraphs all 13 bugs are described in a
short form. The referenced URL within the header of this advisory
will be updated with more detailed information (incl. snippets)
when the Ethereal developers have released 0.10.3.


[01] NetFlow v9 Dissector Template Caching Overflow
---------------------------------------------------

Desc: When parsing the v9_template structure within a NetFlow
UDP packet a template_entry count > 64 will overflow
a stackbuffer and allows overwriting the saved instruction
pointer, thus allowing remote code execution.


[02] IGAP Protocol Dissector Account Overflow
[03] IGAP Protocol Dissector Message Overflow
---------------------------------------------

Desc: When parsing an IGAP protocol packet that contains either
an overlong accountname (>17) or an overlong message (>65)
different buffers may overflow the stack, allowing an over-
write of up to 238 (or 190) bytes. In both cases remote
code execution exploitation is possible.


[04] EIGRP Protocol TLV_IP_INT Long IP Address Overflow
-------------------------------------------------------

Desc: When parsing an EIGRP IP packet that contains an overlong
IP address this will overflow a stack buffer and therefore can
lead to remote code execution


[05] EIGRP Protocol TLV_IP_EXT Long IP Address Overflow
-------------------------------------------------------

Desc: When parsing an EIGRP Extended IP packet that contains an
overlong extended IP address this will overflow a stack buffer
and can lead to remote code execution


[06] PGM Protocol NakList Overflow
----------------------------------

Desc: When parsing an PGM packet with a carefully crafted NakList
a possible integer underflow can result in a very small stack-
overflow. Due to the stacklayout code execution exploitation
seems very unlikely.


[07] IRDA Protocol Plugin IRCOM_PORT_NAME Overflow
--------------------------------------------------

Desc: When parsing an IRCOM_PORT_NAME packed an overlong portname
can overwrite up to 2 bytes on the stack. Similar to [06] the
stacklayout seems to make remote code execution very difficult
or impossible.


[08] BGP Protocol MPLS Label Overflow
-------------------------------------

Desc: When parsing a BGP Packet with a MPLS IPv6 label up to 13
bytes on the stack may be overwritten with arbitrary data.
Due to the stacklayout exploitability seems unlikly and was
therefore not tested.


[09] ISUP Protocol INTERWORKING FUNCTION ADDRESS Overflow
---------------------------------------------------------

Desc: When parsing an ISUP Packet an oversized IWFA will overflow
a stack buffer and can lead to remote code execution


[10] TCAP Protocol TID Overflow
-------------------------------

Desc: When handling the ASN.1 encoded Transaction ID within a TCAP
packet a 4 byte stack variable may overflow and can lead to
remote code execution


[11] UCP Protocol Handle String-Field Overflow
----------------------------------------------

Desc: When handling a string within an UCP packet a stack buffer
of BUFSIZ bytes may overflow and can therefore lead to
remote code execution.
To exploit this vulnerability over the wire an attacker must
be able to fit more than BUFSIZ bytes into one TCP packet.
This means it is only exploitable on the wire if the system
has a MTU bigger than BUFSIZ. BUFSIZ is 8192 on glibc
systems, 1024 on BSD systems and 512 on Windows systems.


[12] UCP Protocol Handle Int-Field Overflow
----------------------------------------------

Desc: When handling an Integer field within an UCP packet a stack
buffer of BUFSIZ bytes may overflow and can therfore lead to
remote code execution.
To exploit this vulnerability over the wire an attacker must
be able to fit more than BUFSIZ bytes into one TCP packet.
This means it is only exploitable on the wire if the system
has a MTU bigger than BUFSIZ. BUFSIZ is 8192 on glibc
systems, 1024 on BSD systems and 512 on Windows systems.


[13] UCP Protocol Handle Time-Field Overflow
----------------------------------------------

Desc: When handling a Time field within an UCP packet a stack
buffer of BUFSIZ bytes may overflow and can therefore lead
to remote code execution.
To exploit this vulnerability over the wire an attacker must
be able to fit more than BUFSIZ bytes into one TCP packet.
This means it is only exploitable on the wire if the system
has a MTU bigger than BUFSIZ. BUFSIZ is 8192 on glibc
systems, 1024 on BSD systems and 512 on Windows systems.


Proof of Concept:

e-matters is not going to release an exploit for any of these
vulnerabilities to the public.


Disclosure Timeline:

5. March 2004 - Ethereal developers were contacted by email
telling them about 10(of the 13) holes.
6 holes were closed the same day EIGRP, IGAP,
ISUP and BGP.
7. March 2004 - IRDA hole closed (after checking specs)
8. March 2004 - PGM hole closed (after checking specs)
9. March 2004 - NetFlow hole closed (after checking specs)
17. March 2004 - UCP holes were discovered and mailed to vendor
19. March 2004 - UCP and TCAP holes closed (after checking specs)
22. March 2004 - Ethereal developers have releases a mini advisory
urging their users to upgrade to version 0.10.3
which will be released later this week
23. March 2004 - Public Disclosure


CVE Information:

The Common Vulnerabilities and Exposures project (cve.mitre.org) has
assigned the name CAN-2004-0176 to this issue.


Recommendation:

Until you can upgrade to version 0.10.3 of Ethereal or to the
bugfixed package from your distributor it is strongly recommended
to disable the following dissectors in the menu:

Analyze->Enabled Protocols

disable: BGP, EIGRP, IGAP, IRDA, ISUP, NetFlow, PGM, TCAP, UCP


GPG-Key:

http://security.e-matters.de/gpg_key.asc

pub 1024D/75E7AAD6 2002-02-26 e-matters GmbH - Securityteam
Key fingerprint = 43DD 843C FAB9 832A E5AB CAEB 81F2 8110 75E7 AAD6


Copyright 2004 Stefan Esser. All rights reserved.


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