Transport Layer Security Renegotiation Remote Man-in-the-Middle Attack Vulnerability

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Updated:October 7, 2015
Document ID:1454777313087163

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Cisco Security Advisory

Transport Layer Security Renegotiation Remote Man-in-the-Middle Attack Vulnerability

Medium
Advisory ID:
Cisco-SA-20091105-CVE-2009-3555
First Published:
2009 November 5 19:53 GMT
Last Updated: 
2012 August 14 16:24 GMT
Version 75.0:
Final
Workarounds:
See below
CVE-2009-3555
CWE-20
CVSS Score:
Base 4.3, Temporal 3.4Click Icon to Copy Verbose Score
AV:N/AC:M/Au:N/C:N/I:P/A:N/E:POC/RL:OF/RC:C
CVE-2009-3555
CWE-20

Summary

  • Multiple Transport Layer Security (TLS) implementations contain a vulnerability when renegotiating a TLS session that could allow an unauthenticated, remote attacker to conduct a man-in-the-middle attack.

    The vulnerability exists during a TLS renegotiation process. If an attacker can intercept traffic from a client to a TLS server, the attacker could stage a rogue TLS server to intercept that traffic and appear to authenticate the client to what the client thinks is the desired TLS server. The attacker is then able to authenticate to the legitimate TLS server and thus stage a man-in-the-middle attack. However, the attacker would not be able to view the contents of the session and would only be able to inject data or requests into it.

    Proof-of-concept code that exploits this vulnerability is publicly available.

    OpenSSL has confirmed this vulnerability in a changelog and released updated software.

    To exploit this vulnerability, the attacker must be able to intercept traffic from a TLS client to a TLS server. In many cases, this may require the attacker to have access to a network that is adjacent to the targeted user's system. Another possibility would be for the attacker to have access to a network that is adjacent to a legitimate TLS server.

    This vulnerability is likely to affect multiple implementations of TLS.

Affected Products

Workarounds

  • Administrators are advised to apply the appropriate updates.

    Administrators are advised to physically secure internal networks and use switches rather than hubs to route the data.

    Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.

Fixed Software

Exploitation and Public Announcements

  • The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

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Revision History

  • VersionDescriptionSectionStatusDate
    1.0Initial ReleaseNAFinal2009-Nov-05
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Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

Subscribe to Cisco Security Notifications