Preliminary Report on Bogus DigiNotar Certificates

Tuesday, September 06, 2011



After a falsely issued Google SSL certificate had been discovered last week by Ali Borhani, an Iranian freelance web developer, security auditors at Fox-IT were asked to conduct an investigation.

Early reports indicated that the bogus digital certificates may have been part of a ploy by the Iranian government to perform Man-in-the-Middle (MitM) attacks and gather intelligence on Iranian opposition groups.

Digital certificates are used by internet browsers to recognized legitimate websites and protect surfers from inadvertently exposing themselves to malware, phishing scams, impostors and spoofed landing sites.

According to a report in SoftPedia, Dutch SSL certificate authority (CA) DigiNotar may have issued hundreds of rogue digital certificates aside from the Google certificate discovered by Borhani.

The preliminary report from Fox-IT states:

The goal of this report is to share relevant information with DigiNotar stakeholders (such as the Dutch Government and the Internet community), based on which they can make their own risk analysis. Because this is a public report, some investigation results and details cannot be included for privacy and/ or security reasons.

Since the investigation has been more of a fact finding mission thus far, we will not draw any conclusions with regards to the network-setup and the security management system. In this report we will not give any advice to improve the technical infrastructure for the long term. Our role is to investigate the incident and give a summary of our findings until now. We leave it to the reader in general and other responsible parties in the PKI- and internet community to draw conclusions, based on these findings. We make a general reservation, as our investigations are still on going.

Fox-IT was given access to a report produced by another IT-security firm which performs the regular penetration testing and auditing for DigiNotar. The main conclusions from this report dated July 27th were:

A number of servers were compromised. The hackers have obtained administrative rights to the outside webservers, the CA server “Relaties-CA” and also to “Public-CA”. Traces of hacker activity started on June 17th and ended on July 22nd.

Furthermore, staff from DigiNotar and the parent company Vasco performed their own security investigation. E-mail communication and memos with further information were handed over to us.

This information gave us a rough overview of what happened:

- The signing of 128 rogue certificates was detected on July 19th during the daily routine security check. These certificates were revoked immediately;

- During analysis on July 20th the generation of another 129 certificates was detected. These were also revoked on July 21th;

- Various security measures on infrastructure, system monitoring and OCSP validation have been taken immediately to prevent further attacks.

- More fraudulent issued certificates were discovered during the investigation and 75 more certificates were revoked on July 27th.

- On July 29th a * certificate issued was discovered that was not revoked before. This certificate was revoked on July 29th.

- DigiNotar found evidence on July 28th that rogue certificates were verified by internet addresses originating from Iran.

On August 30th Fox-IT was asked investigate the incident and recommend and implement new security measures. Fox-IT installed a specialized incident response

An improperly issued digital certificate for an unqualified domain name would allow an attacker to conduct exploits accompanied by validly signed and authenticated certificates.

Though the bogus certificates have been revoked, they may still be in use, as many browsers do not check for a revoked status.

The Iranian government could be interested in using MitM attacks to monitor Internet usage, redirect dissident web surfers, and collect intelligence on opposition factions.

A MitM attack takes a request for an HTTPS encrypted site and inserts and intermediary website in the process while creating the encrypted link with the target system while still being able to monitor the data transferred before it is encrypted.

Possibly Related Articles:
Encryption SSL Iran Digital Certificates report HTTPS Investigation DigiNotar Fox-IT
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