Lenovo ThinkVantage System Update Certificate Validation Flaw Lets Remote Users Spoof the Update Server
SecurityTracker Alert ID: 1020112|
SecurityTracker URL: http://securitytracker.com/id/1020112
(Links to External Site)
Updated: Jul 22 2008|
Original Entry Date: May 27 2008
Modification of authentication information|
Vendor Confirmed: Yes |
Version(s): System Update 3; 3.13.0005, Build date 2008-1-3; possibly other versions|
A vulnerability was reported in Lenovo ThinkVantage System Update. A remote user can spoof the update server.|
The client software does not validate the certificate chain for certificates supplied by the remote update server. A remote user that can spoof DNS can return a specially crafted certificate to the target client to cause the client to accept the connection and download arbitrary code.
The vendor was notified on February 2, 2008.
Derek Callaway of Security Objectives reported this vulnerability.
The original advisory is available at:
A remote user can spoof the update server to potentially download arbitrary code to the target client system.|
The vendor plans to issue a fix as part of Maintenance Release 4, to be available at:|
Vendor URL: www-307.ibm.com/pc/support/site.wss/TVSU-UPDATE.html (Links to External Site)
Access control error|
|Underlying OS: Windows (2000), Windows (Vista), Windows (XP)|
Source Message Contents
Subject: [Full-disclosure] SECOBJADV-2008-01: Lenovo SystemUpdate SSL|
= Security Objectives Advisory (SECOBJADV-2008-01) =
Lenovo SystemUpdate SSL Certificate Issuer Spoofing Vulnerability
AFFECTED: Lenovo System Update 3 (Version 3.13.0005, Build date 2008-1-3)
PLATFORM: Intel / Windows
CLASSIFICATION: Trust of OpenSSL Certificate Without Validation (CWE-599)
RESEARCHER: Derek Callaway
IMPACT: Client-side code execution
System Update(tm) helps you reduce the time, effort, and expense required to
support and maintain the latest drivers, BIOS, and other applications for
Think or Lenovo systems. It enables you to get the latest updates from the
Lenovo support site, or to automatically schedule your system to be updated.
Lenovo System Update allows arbitrary update executables to be downloaded and
installed from a rogue server. The Client DLL does not perform certificate
chain verification when initiating an SSL connection with the server. Instead,
it performs a string comparison on the Issuer field of the X.509 certificate
in order to determine if it appears to belong to IBM. After successful SSL
negotiation, the client proceeds to download XML files that contain pathnames
to EXE files, their sizes, and corresponding SHA-1 hashes (although the XML
element defining the SHA value is named "CRC.") If an XML file shows a newer
software version than what it is already installed, it downloads the EXE file,
calculates its SHA-1 hash and compares it against the one defined in the XML
file; if they match, it runs the executable with administrator privileges.
In order to exploit this vulnerability an attacker would create a self-signed
SSL certificate with X.509 header values (issuer, common name, organization,
etc.) of the real public SSL certificate used by the SystemUpdate server at
download.boulder.ibm.com. The attacker would also modify the XML config file
for the target package with a new version number, file size, and SHA-1 hash
that correspond to a malicious EXE file. In theory, an attacker could inject
a completely new package into QuestResponse.xml although this was not tested
by Security Objectives.
When SystemUpdate attempts to make a connection to the server, the attacker
would accept the connection through DNS spoofing, ARP redirection, etc. Users
of wireless networks are at high risk because access point impersonation will
simplify the attack. Once SystemUpdate makes the connection to TCP port 443,
the rogue server negotitates an SSL session with the attacker-created SSL
certificate. The rogue HTTPS server will then send the malicious XML and EXE
files when SystemUpdate requests the target package. All other requests will
be conducted as usual by proxying requests to the real SystemUpdate server or
maintaining a mirrored version of it.
One potential work-around is to disable scheduled updates and not execute
Lenovo SystemUpdate although this may expose the user to other vulnerabilities
since software patches will not be installed.
ThinkVantage SystemUpdate MR4 is in golden release stage at the time of writing.
23-Jan-2008 Discovery of Vulnerability
30-Jan-2008 Developed Proof-of-Concept
02-Feb-2008 Reported to Vendor
19-Feb-2008 Discussed Exploitation
14-Apr-2008 Wrote Patch
18-Apr-2008 Tested Patch
20-May-2008 Released Patch
25-May-2008 Published Advisory
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