rdesktop Integer Underflow in iso_recv_msg() Lets Remote Users Execute Arbitrary Code
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SecurityTracker Alert ID: 1019990
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SecurityTracker URL: http://securitytracker.com/id?1019990
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CVE Reference: CVE-2008-1801
(Links to External Site)
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Date: May 8 2008
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Impact: Execution of arbitrary code via network, User access via network
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Fix Available: Yes
Vendor Confirmed: Yes
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Advisory: iDEFENSE
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Version(s): 1.5.0
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Description: A vulnerability was reported in rdesktop. A remote user can execute arbitrary code on the target system.
A remote RDP server can send a specially crafted reply to the connected target user to trigger an integer underflow and execute arbitrary
code on the target user's system. The code will run with the privileges of the target user.
The vulnerability resides in the
iso_recv_msg() function in 'iso.c'.
The vendor was notified on November 12, 2007.
An anonymous researcher reported this vulnerability
via iDefense.
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Impact: A remote server can execute arbitrary code on the connected target user's system.
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Solution: The vendor has issued a source code fix, available at:
http://rdesktop.cvs.sourceforge.net/rdesktop/rdesktop/iso.c?annotate=1.20&diff_format=h&pathrev=HEAD#l101
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Vendor URL: www.rdesktop.org/ (Links to External Site)
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Cause: Boundary error
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Underlying OS: Linux (Any), UNIX (Any)
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Reported By: iDefense Labs Security Advisories <idlabs-advisories@idefense.com>
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Message History:
This archive entry has one or more follow-up message(s) listed below.
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Source Message Contents
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Date: Wed, 07 May 2008 19:37:22 -0400
From: iDefense Labs Security Advisories <idlabs-advisories@idefense.com>
Subject: iDefense Security Advisory 05.07.08: Multiple Vendor rdesktop
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iDefense Security Advisory 05.07.08
http://labs.idefense.com/intelligence/vulnerabilities/
May 07, 2008
I. BACKGROUND
rdesktop is an open source client that speaks the Remote Desktop
Protocol (RDP). This allows Unix-based users to login to Windows
Terminal Servers. More information is available at the following URL.
http://www.rdesktop.org/
II. DESCRIPTION
Remote exploitation of an integer underflow vulnerability in rdesktop,
as included in various vendors' operating system distributions, allows
attackers to execute arbitrary code with the privileges of the
logged-in user.
The vulnerability exists within the code responsible for reading in an
RDP request. When reading a request, a 16-bit integer value that
represents the number of bytes that follow is taken from the packet.
This value is then decremented by 4, and used to calculate how many
bytes to read into a heap buffer. The subtraction operation can
underflow, which will then lead to the heap buffer being overflowed.
III. ANALYSIS
Exploitation of this vulnerability results in the execution of arbitrary
code with the privileges of the logged in user. In order to exploit this
vulnerability, an attacker must persuade a targeted user to connect to a
malicious RDP server.
IV. DETECTION
iDefense confirmed the existence of this vulnerability in rdesktop
version 1.5.0. Previous versions may also be affected.
V. WORKAROUND
iDefense is currently unaware of any effective workaround for this
issue.
VI. VENDOR RESPONSE
The rdesktop maintainer has addressed this vulnerability with CVS
revision 1.20 of iso.c. For more information, visit the following URL.
http://rdesktop.cvs.sourceforge.net/rdesktop/rdesktop/iso.c?annotate=1.20&diff_format=h&pathr
ev=HEAD#l101
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2008-1801 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
11/12/2007 Initial vendor notification
11/19/2007 Initial vendor response
05/07/2008 Public disclosure
IX. CREDIT
The discoverer of this vulnerability wishes to remain anonymous.
Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php
Free tools, research and upcoming events
http://labs.idefense.com/
X. LEGAL NOTICES
Copyright © 2008 iDefense, Inc.
Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDefense. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically,
please e-mail customerservice@idefense.com for permission.
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.
_______________________________________________
To unsubscribe, go here:
http://www.idefense.com/mailman/listinfo/idlabs-advisories
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