Microsoft Windows Secure Channel integer underflow

ID VU:810073
Type cert
Reporter CERT
Modified 2007-06-14T19:35:00



A vulnerability in Microsoft Windows Secure Channel security package may lead to execution of arbitrary code.


Microsoft Windows Secure Channel (Schannel) security package implements standard network authentication protocols Secure Sockets Layer (SSL) and Transport Layer Security (TLS). A vulnerability exists in the way Schannel handles specially crafted digital signatures from the server during the SSL handshake, which can result in an integer underflow and heap memory corruption. According to Microsoft Security Bulletin ms07-031:

Schannel performs insufficient checks for specially crafted server-sent digital signatures during the SSL handshake.


According to Microsoft Security Bulletin ms07-031 this vulnerability affects different versions of Microsoft Windows differently:

_On Windows XP... An attacker who successfully exploited this vulnerability could remotely take complete control of an affected system.

On Windows 2000 this vulnerability could cause the affected system to stop accepting SSL and TLS connections.

On Windows 2003, the vulnerability could cause the affected system to automatically restart._

See Microsoft Security Bulletin ms07-031 for more detailed information.


Microsoft has released an update to address this issue. See Microsoft Security Bulletin ms07-031 for more details.

Do not follow unsolicited links

In order to convince users to visit their sites, attackers often use URL encoding, IP address variations, long URLs, intentional misspellings, and other techniques to create misleading links. Do not click on unsolicited links received in email, instant messages, web forums, or internet relay chat (IRC) channels. Type URLs directly into the browser to avoid these misleading links. While these are generally good security practices, following these behaviors will not prevent exploitation of this vulnerability in all cases, particularly if a trusted site has been compromised or allows cross-site scripting.

Vendor Information


Filter by status: All Affected Not Affected Unknown

Filter by content: __ Vendor has issued information

__ Sort by: Status Alphabetical

Expand all

Javascript is disabled. Click here to view vendors.

Microsoft Corporation Affected

Updated: June 13, 2007



Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


Refer to Microsoft Security Bulletin ms07-031.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

CVSS Metrics

Group | Score | Vector
Base | |
Temporal | |
Environmental | |


  • <>
  • <>
  • <>


This vulnerability was reported in Microsoft Security Bulletin ms07-031. Microsoft credits Thomas Lim of COSEINC with reporting this issue.

This document was written by Chris Taschner.

Other Information

CVE IDs: | CVE-2007-2218
Severity Metric: | 24.30
Date Public: | 2007-06-12
Date First Published: | 2007-06-14
Date Last Updated: | 2007-06-14 19:35 UTC
Document Revision: | 16