Iranian internet users whose security may have been compromised by the forged Google.com digital certificate could number in the hundreds of thousands. An interim report (PDF) commissioned by DigiNotar, the certification authority (CA) at the centre of the hacking incident, also reveals lax security at the Dutch firm.
"Around 300,000 unique requesting IPs to google.com have been identified. Of these IPs >99% originated from Iran," said the report, which was based on an analysis of DigiNotar's server logs by Dutch information security firm Fox-IT. "A sample of the IPs outside of Iran showed mainly to be TOR-exit nodes, proxies and other (VPN) servers, and almost no direct subscribers."
TOR is a network of servers that hides the origin of web browsing sessions, allowing anonymous internet use.
The rogue DigiNotar certificate may have been used in a man-in-the-middle attack to intercept a user's Google login. If their Google login cookie were intercepted, this would allow the attacker to log in directly to their Gmail inbox to read email, and access other Google services including stored location information from Latitude and documents in GoogleDocs.
"Once the hacker is able to receive his targets' e-mail he is also able to reset passwords of others [sic] services like Facebook and Twitter using the lost password button," the report said.
DigiNotar's network was "severely breached", with numerous security flaws.
"All CA servers were members of one Windows domain, which made it possible to access them all using one obtained user/password combination. The password was not very strong and could easily be brute-forced," the report said.
Software on the public web servers was outdated and not patched, no secure central network logging was in place, and the servers investigated by Fox-IT had no anti-virus protection.
"The most critical servers contain[ed] malicious software that can normally be detected by anti-virus software," the report said.
"A number of malicious/hacker software tools was found. These vary from commonly used tools such as the famous Cain & Abel tool to tailor made software. Specifically developed software probably enabled the hackers to upload the generated certificates to a dropbox."
Fox-IT found that a total of 531 fraudulent certificates have been issued. They include certificates for the domains android.com, aol.com, logmein.com, microsoft,com, mossad.gov.il, the UK's MI6 at sis.gov.au, skype.com, torproject.org, twitter.com, windowsupdate.com and wordpress.com.
Fox-IT's investigation team included forensic experts, cybercrime investigators, malware analysts and a security expert with PKI experience, and was headed directly by CEO J R Prins.