iDefense Security Advisory 04.15.10
http://labs.idefense.com/intelligence/vulnerabilities/
Apr 15, 2010

I. BACKGROUND

Agent Extensibility (AgentX) Protocol was designed to address
interoperability issues with extensible SNMP agents. AgentX++ is a C++
implementation of the AgentX protocol. It is one of several C++ based
SNMP libraries developed by Frank Fock. For more information refer to
the URLs below.

http://www.agentpp.com/

http://www.ietf.org/rfc/rfc2741.txt

II. DESCRIPTION

Remote exploitation of an integer overflow vulnerability within
AgentX++, as distributed with multiple vendors' products, allows
attackers to execute arbitrary code with the privileges of the AgentX
master process.

This vulnerability exists within the AgentX::receive_agentx function. If
an attacker sends a request specifying the maximum 32-bit integer as the
payload length, adding one will cause an integer overflow, resulting in
the allocation of a "0" size buffer. Since an attacker can send as
much, or as little, data as they wish, they can overflow the allocated
heap buffer by an arbitrary amount.

III. ANALYSIS

Exploitation allows an attacker to execute arbitrary code with the
privileges of the running AgentX master process. In order to exploit
this vulnerability, the attacker must be able to connect to the AgentX
master port, usually TCP port 705. No authentication is required.

The privileges with which this process runs varies in other situations.
In order to listen on ports below 1024, root privileges are required.
The master agent included with RealNetwork Helix Server v12 does not
drop privileges after opening this port.

Although the issue is present in the Windows version of Helix Server
v12, it is not exploitable due the implementation of the "recv"
function in Winsock. In Windows, the "recv" function buffers incoming
data, and will return a "WSAENOBUFS" error when a request is made for
more bytes than will fit in the buffer. No data is read in this case.

IV. DETECTION

iDefense confirmed the existence of this vulnerability in the following
environments:

  RealNetworks Helix Server v12 on Linux
  RealNetworks Helix Server v12 on Windows 2003 SP2
  AgentX++ source code v1.4.16

All products utilizing the AgentX++ library are suspected to be
vulnerable. Helix Server and Helix Mobile server versions prior to
14.0.0 are vulnerable (11.x,12.x and 13.x series).

V. WORKAROUND

iDefense is currently unaware of any workarounds for this issue.

VI. VENDOR RESPONSE

RealNetworks Inc. has released a patch which addresses this issue. For
more information, consult their advisory at the following URL.
http://www.realnetworks.com/uploadedFiles/Support/helix-support/Securi
tyUpdate041410HS.pdf

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2010-1319 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

11/03/2008  Initial Vendor Notification
01/14/2009  Initial Vendor Reply
04/15/2010  Coordinated Public Disclosure

IX. CREDIT

This vulnerability was discovered by Joshua J. Drake of iDefense Labs.

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X. LEGAL NOTICES

Copyright © 2010 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.