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Microsoft Secure Channel (Schannel) vulnerable to remote code execution via specially crafted packets

Vulnerability Note VU#505120

Original Release Date: 2014-11-13 | Last Revised: 2014-11-17


A critical vulnerability in Microsoft Windows systems could allow a remote attacker to execute arbitrary code via specially crafted network packets.


Microsoft Secure Channel (Schannel) is a security package that provides SSL and TLS on Microsoft Windows platforms. Due to a flaw in Schannel (CVE-2014-6321), a remote attacker could execute arbitrary code on both client and server applications.

It may be possible for exploitation to occur without authentication and via unsolicited network traffic. According to Microsoft MS14-066, there are no known mitigations or workarounds.

Microsoft patches are typically reverse-engineered and exploits developed in a matter of days or weeks. An anonymous Pastebin user has threatened to publish an exploit on Friday, November 14, 2014. Immunity Inc. has developed a proof of concept exploit for their CANVAS tool.

ANEXIA has published a tool to test if a system is vulnerable.


This flaw allows a remote attacker to execute arbitrary code and fully compromise vulnerable systems.


Apply an update

Microsoft has released Security Bulletin MS14-066 to address this vulnerability in supported operating systems.

Vendor Information

Many versions of Microsoft Windows operating systems are confirmed vulnerable, including:

      • Microsoft Windows Vista, 7, 8, 8.1, RT, and RT 8.1
      • Microsoft Windows Server 2003, 2008, 2008 R2, 2012, and 2012 R2
Unsupported operating systems such as Microsoft Windows XP and 2000 may also be affected.


Microsoft Corporation Affected

Updated:  November 13, 2014



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.

Vendor References

CVSS Metrics

Group Score Vector
Base 10 AV:N/AC:L/Au:N/C:C/I:C/A:C
Temporal 8.3 E:F/RL:OF/RC:C
Environmental 9.0 CDP:MH/TD:H/CR:ND/IR:ND/AR:ND



This document was written by Joel Land.

Other Information

CVE IDs: CVE-2014-6321
Date Public: 2014-11-11
Date First Published: 2014-11-13
Date Last Updated: 2014-11-17 16:02 UTC
Document Revision: 27

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