Infrastructure Compromise Put Fraudulent SSL Certificates in the Hands of Attackers

Netherlands-based DigiNotar, a subsidiary of VASCO Data Security, disclosed that an intrusion into its Certificate Authority (CA) infrastructure resulted in the fraudulent issuance of SSL certificates for several domains, including Google.com and CIA.gov.

The fraudulent SSL certificate could be used by an attacker to masquerade as any subdomain of google.com, and could be used to spoof content, perform phishing attacks, or perform man-in-the-middle attacks against Web browsers.

DigiNotar this week said that it detected the intrusion on July 19th, 2011 and that the attack was targeted at its Certificate Authority infrastructure for issuing SSL and EVSSL certificates. Following an initial external security audit, the company thought it had revoked all fraudulently issued certificates, but after being notified by Dutch government organization Govcert, it was discovered that at least one fraudulent certificate, the one for Google.Com, had not been revoked at the time. DigiNotar says it has since revoked the fraudulent certificate.

While most users should be protected since the certificate has been revoked by DigiNotar, Mozilla and Microsoft have issued updates in response to the incident, and users and administrators should apply any necessary updates to help mitigate any associated risks.

Because the extent of the incident isn’t clear, Mozilla is releasing new versions of Firefox for desktop (3.6.21, 6.0.1, 7, 8, and 9) and mobile (6.0.1, 7, 8, and 9), Thunderbird (3.1.13, and 6.0.1) and SeaMonkey (2.3.2) shortly that will revoke trust in the DigiNotar root and protect users from this attack. Mozilla also highlighted how users can manually disable the DigiNotar root through the Firefox preferences.

In response to the incident, Microsoft said it has removed the DigiNotar root certificate from the Microsoft Certificate Trust List, a list used by Windows Vista, Windows 7, Windows Server 2008, and Windows Server 2008 R2 to validate the trust of a certification authority. Users of these operating systems will be presented with an invalid certificate error when they browse to a Web site or try to install programs signed by the DigiNotar root certificate, Microsoft said. In those cases users should follow the instructions in the message. Microsoft will release a future update to address this issue for all supported editions of Windows XP and Windows Server 2003. Additional information can be found in Microsoft Security Advisory 2607712.

“This latest CA compromise is further evidence that when improperly managed, digital certificates and encryption keys can quickly become liabilities, allowing cybercriminals to turn security assets into attack vectors,” said Jeff Hudson, CEO of Venafi, an Internet security company that provides enterprise key and certificate management solutions. “These attacks are extremely disruptive. Beyond the security hazards, organizations also face costly reputational damage. Organizations have to improve how they manage and secure their SSL infrastructure to prevent breaches, and be able to quickly respond to minimize their impact if they occur.”

DigiNotar temporarily suspended the sale of its SSL and EVSSL certificate offerings and will only restart its SSL and EVSSL certificate activities after it completes additional security audits by third party organizations.