iDefense Security Advisory 01.09.08
http://labs.idefense.com/intelligence/vulnerabilities/
Jan 09, 2008

I. BACKGROUND

The Novell Client software provides a workstation with access to Novell
NetWare networks as well as Novell Open Enterprise Server (OES)
services. Novell Clients can access the full range of Novell services
such as authentication via Novell eDirectory, network browsing and
service resolution, and secure and reliable file system access. More
information about the Novel Client can be found on the vendor's web
site at the following URL.

http://www.novell.com/products/clients/

II. DESCRIPTION

Local exploitation of an input validation error vulnerability within
Novell Inc.'s NetWare Client allows attackers to execute arbitrary code
within the kernel.

When the Novell NetWare Client is installed on a Windows-based operating
system, the driver nicm.sys will be loaded at system startup. This
driver allows any user to open the device "\\.\nicm" and issue IOCTLs
with a buffering mode of METHOD_NEITHER.

Due to insufficient input validation, user mode software can pass kernel
addresses as arguments to the driver. By using specially constructed
input, a malicious user can use functionality within the driver to
patch kernel addresses and execute arbitrary code in kernel mode.

III. ANALYSIS

Exploitation of this vulnerability allows a local attacker to execute
arbitrary code within the kernel. To exploit the vulnerability, the
attacker must be able execute a specially crafted executable on the
targeted computer.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in nicm.sys,
file version 3.0.0.4, as included with Novell's NetWare Client 4.91
SP4. Other versions may also be vulnerable.

V. WORKAROUND

iDefense is currently unaware of any workaround for this issue.

VI. VENDOR RESPONSE

Novell Inc. has addressed this vulnerability by releasing a patch for
the NetWare Client SP3. For more information visit the following URL.

http://download.novell.com/Download?buildid=4FmI89wOmg4~

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-5762 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

10/30/2007  Initial vendor notification
11/13/2007  Initial vendor response
01/09/2008  Coordinated public disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Stephen Fewer of Harmony
Security (www.harmonysecurity.com)

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X. LEGAL NOTICES

Copyright © 2008 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.