Vodafone, EE and O2 mobile phones believed compromised in GCHQ SIM card hack
Security services stole SIM card encryption keys from maker Gemalto to help hack mobile phone network
GCHQ and the US National Security Agency hacked into the internal network of the largest makers of mobile phone SIM cards in the world in order to steal encryption keys and compromise the security of mobile phones on the Vodafone, EE and O2 networks.
That is the latest claim to come out of the cache of documents leaked by NSA whistleblower Edward Snowden and published this evening by The Intercept.
Gemalto, the company targetted by the two intelligence agencies, makes two billion SIM cards every year, which are used by more than 400 mobile phone networks around the world, including all the US networks.
By being able to crack the encryption that protects mobile phones, the security services were able to tap communications at will of anyone without the approval of either governments or telecoms companies. It also enabled them to break encrypted communications that had already been intercepted, but which it lacked the ability to decrypt.
According to The Intercept, the initiative required a major effort to compromise the security of engineers working for Gemalto and its contractors across the world - without raising suspicion of the company, which also makes smartcards for the banking industry. The company only began investigating the breach yesterday after being contacted by the investigative news website.
"According to one secret GCHQ slide, the British intelligence agency penetrated Gemalto's internal networks, planting malware on several computers, giving GCHQ secret access. We 'believe we have their entire network', the slide's author boasted about the operation against Gemalto," The Intercept reports.
It continues: "Additionally, the spy agency targeted unnamed cellular companies' core networks, giving it access to 'sales staff machines for customer information and network engineers machines for network maps'. GCHQ also claimed the ability to manipulate the billing servers of cell companies to 'suppress' charges in an effort to conceal the spy agency's secret actions against an individual's phone.
"Most significantly, GCHQ also penetrated 'authentication servers', allowing it to decrypt data and voice communications between a targeted individual's phone and his or her telecom provider's network. A note accompanying the slide asserted that the spy agency was 'very happy with the data so far and [was] working through the vast quantity of product'."
The compromise was the work of the Mobile Handset Exploitation Team, which was only set-up in April 2010 to target vulnerabilities in mobile phones and the cellular network. One of its main objectives was to penetrate the networks of companies that manufacture mobile phone SIM cards, as well as the mobile phone operators themselves.
According to The Intercept, GCHQ first broke into email and Facebook accounts of Gemalto engineers and people working at the mobile phone operators and other SIM card manufacturers - using the NSA's X-KEYSCORE programme. This provided a springboard enabling them to scour their emails and other communications, utilising their social networks to find people who might have access to the companies' core networks.
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Vodafone, EE and O2 mobile phones believed compromised in GCHQ SIM card hack
Security services stole SIM card encryption keys from maker Gemalto to help hack mobile phone network
The Intercept says that the objective was first to find information that would help overcome Gemalto's security in order to make it possible to clandestinely copy encryption keys in bulk destined for use on SIM cards destined for mobile phone operators.
It continues: "Hackers working for GCHQ focused on 'harvesting' massive amounts of individual encryption keys 'in transit between mobile network operators and SIM card personalisation centres' like Gemalto. The spies 'developed a methodology for intercepting these keys as they are transferred between various network operators and SIM card providers'. By that time, GCHQ had 'developed "an automated technique with the aim of increasing the volume of keys that can be harvested'."
The leaked documents suggest that the encryption keys for the SIM cards were frequently transferred using insecure methods, such as email or FTP with only basic encryption methods applied. "To get bulk access to encryption keys, all the NSA or GCHQ needed to do was intercept emails or file transfers as they were sent over the Internet - something both agencies already do millions of times per day."
It's first initial efforts in the first quarter of 2010 enabled it to pick-up encryption keys for SIM cards destined for mobile operators in Iran, Afghanistan, Yemen, India, Serbia, Iceland and Tajikistan. However, GCHQ was unable to crack the security used by mobile operators in Pakistan and steal encryption keys for use on SIM cards by Pakistani mobile operators.
The SIM card in every mobile phone was developed to stamp out mobile phone fraud, and also holds encryption keys that both authenticate the phone and its user, as well as encrypting or decrypting communications from or to the phone. In some countries, the SIM cards are also used as part of a money transfer system and compromises could therefore undermine the integrity of key parts of developing economies.
The encryption keys are burned directly onto the SIM cards at the factory, and the SIM helps authenticate the phone and user with the network using that key.
Computing is currently awaiting comment from all the UK's big mobile phone networks to confirm their usage of Gemalto SIM cards.
Gemalto wasn't the only SIM card maker targetted. Documents from May 2011 indicate that GCHQ was preparing to assault German SIM card makers Giesecke and Devrient, although it is not known whether GCHQ was successful.