SIM card vulnerabilities easy to fix, researcher says

Operators and SIM card vendors haven't played the blame game and are working on fixes

A pair of severe security problems in millions of SIM cards should be easy for operators to fix, according to the German security researcher who found the issues.

Karsten Nohl of Security Research Labs in Berlin previewed research earlier this week that millions of SIM cards are likely still using an outdated, 1970s-era form of encryption to authenticate over-the-air (OTA) software updates.

Nohl found it was possible to trick some kinds of SIM cards into divulging an encrypted 56-bit DES (Data Encryption Standard) key, which can be decrypted using a regular computer. He discovered that by sending a bogus OTA update to a phone, some SIMs returned an error code containing the weak key.

A device could then be sent spyware which accesses critical phone data through the card's Java Virtual Machine, a software framework present on almost every SIM sold worldwide.

Nohl said in an interview Tuesday that 500 million phones, regardless of make, could be vulnerable, based on his sample of 1,000 SIM cards from a variety of operators, mostly in Europe.

But the weak encryption problem and mistake of returning an error code with a weak key can be fixed in the same way it can be exploited: through an OTA update.

SIM cards come in a wide variety of configurations. Operators will send manufacturers such as Gemalto specifications for SIM cards to be used on their network. Many SIM cards carry older configurations and technology, such as DES, that date back more than a decade, Nohl said.

For some vulnerable SIMs, it may be possible to switch off the DES encryption and turn on Triple DES, a more secure form of encryption that is now used, Nohl said.

Users won't even know their phones are updated, as operators frequently send out updates that are invisible to people using special SMS codes to change, for example, roaming settings, he said. An OTA update can also fix phones that return the revealing error message.

Operators can also make a key adjustment to their SMS centers, which process all SMS messages. Since the SMS codes carrying software updates are very specific, operators can adjust their firewalls to only allow those types of codes to be sent to their users if the codes originate from their servers, Nohl said.

Since so many operators are affected, Nohl said his lab contacted the GSM Association trade group with details of the research, which has issued advisories.

Although there was potential for arguments between operators and SIM card vendors over who was to blame, "everybody was extremely constructive in working to fix the problem, and there was no pointing fingers," Nohl said.

Nohl is due to give a full presentation on July 31 at the Black Hat security conference with more details on the SIM card issues and other vulnerabilities.

Send news tips and comments to Follow me on Twitter: @jeremy_kirk

Join the CSO newsletter!

Error: Please check your email address.

Tags securityGSM AssociationmobileExploits / vulnerabilitiesSecurity Research Labs

More about GemaltoGSM Association

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Jeremy Kirk

Latest Videos

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

  • 150x50

    IDG Live Webinar:The right collaboration strategy will help your business take flight

    Speakers - Mike Harris, Engineering Services Manager, Jetstar - Christopher Johnson, IT Director APAC, 20th Century Fox - Brent Maxwell, Director of Information Systems, THE ICONIC - IDG MC/Moderator Anthony Caruana

    Play Video

More videos

Blog Posts