OpenSSL RSA Signature Forgery Vulnerability

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Updated:October 8, 2015
Document ID:1454772604940663

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Cisco Security Advisory

OpenSSL RSA Signature Forgery Vulnerability

Medium
Advisory ID:
Cisco-SA-20060905-CVE-2007-5810
First Published:
2006 September 5 17:39 GMT
Last Updated: 
2015 January 31 08:15 GMT
Version 61.0:
Final
Workarounds:
See below
CVE-2006-4339
CVE-2007-5810
CVSS Score:
Base 6.4, Temporal 4.7Click Icon to Copy Verbose Score
AV:N/AC:L/Au:N/C:P/I:P/A:N/E:U/RL:OF/RC:C
CVE-2006-4339
CVE-2007-5810

Summary

  • OpenSSL versions 0.9.7j and prior and 0.9.8b and prior contain a vulnerability that could allow an unauthenticated, remote attacker to successfully pass a forged X.509 certificate.

    The vulnerability could allow an unauthenticated, remote attacker to pass a forged Public-Key Cryptography Standards (PKCS)#1 Version 1.5 signature when signed by a certain type of RSA key.  An attacker could exploit the vulnerability to access certificate-protected resources.

    OpenSSL confirmed the vulnerability in a security advisory and released updated versions.



    This vulnerability affects PKCS #1 v1.5 signatures if the exponent of the public key is 3, which is widely used by Certificate Authorities.  An attacker will likely exploit this vulnerability to forge signatures without the secret key.  PKCS #1 v1.5 is often utilized within X.509 certificates; therefore, all applications that use OpenSSL to verify X.509 certificates may be vulnerable, including software that uses OpenSSL for SSL or TLS.

Affected Products

Workarounds

  • Administrators are advised to apply the appropriate updates.

    Administrators are advised to utilize certificates as part of a two-factor authentication system.

    Administrators may consider restricting access to certificate-protected resources to trusted users through the use of a VPN or other remote access technology that is not affected.

    Administrators running ISC BIND using DNSSEC are advised to apply the available software updates, generate new RSA-SHA1 and RSA-MD5 keys for all old keys, and perform a key rollover to the new keys.

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 ReleaseNAFinal2006-Sep-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