Microsoft Windows Remote Desktop Protocol (RDP) uses weak algorithm for encrypting packets

Overview

Microsoft Windows Remote Desktop Protocol (RDP) uses a weak algorithm for encrypting packets.

Description

Microsoft describes RDP as follows.

RDP is based on, and is an extension of, the T.120 protocol family standards. It is a multichannel-capable protocol that allows for separate virtual channels for carrying device communication and presentation data from the server, as well as encrypted client mouse and keyboard data.
Microsoft’s implementation of RDP does not encrypt the checksums of the session data. Therefore, a determined attacker could apply cryptanalytic techniques to recover encrypted session traffic. Note that Microsoft has listed the following mitigating factors:

An attacker would need the ability to capture an RDP session in order to exploit this vulnerability. In most cases, this would require that the attacker have physical access to the network media.

Because encryption keys are negotiated on a per-session basis, a successful attack would allow an attacker to decrypt only a single session and not multiple sessions. Thus, the attacker would need to conduct a separate cryptanalytic attack against each session he or she wished to compromise.

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Impact

A remote attacker could apply cryptanalytic techniques to recover encrypted session traffic.

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Solution

Apply a patch.

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Vendor Information

865833

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Updated: December 06, 2002

Status

Affected

Vendor Statement

See <http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS02-051.asp&gt;

Vendor Information

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

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23865833 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS02-051.asp&gt;
• <http://msdn.microsoft.com/library/en-us/termserv/termserv/using_terminal_services_virtual_channels.asp&gt;
• <http://www.microsoft.com/windows2000/techinfo/howitworks/terminal/rdpfandp.asp&gt;
• <http://link.springer.de/link/service/series/0558/bibs/2139/21390310.htm&gt;
• <http://www.ietf.org/rfc/rfc2104.txt&gt;

Acknowledgements

Ben Cohen & Pete Chown of Skygate Technology Ltd. discovered this vulnerability.

This document was written by Ian A Finlay.

Other Information

CVE IDs:	CVE-2002-0863
Severity Metric:	6.30 Date Public: