Researchers at the Centre for Research on Cryptography and Security at Masaryk University in the Czech Republic said tonight that the product was also present in authentication, signature and encryption tokens of other vendors and chips used for Trusted Boot of operating systems.
The flaw was disclosed to Infineon in February, with agreement that eight months would be allowed to go by without public disclosure.
"We co-operated with the manufacturer and other affected parties to help evaluate and mitigate this vulnerability during this period. Major vendors including Microsoft, Google, HP, Lenovo, Fujitsu already released the software updates and guidelines for a mitigation. We are now notifying general public and releasing tools for assessment of the individual keys," the researchers wrote.
"The vulnerability does NOT depend on a weak or a faulty random number generator – all RSA keys generated by a vulnerable chip are impacted," the researchers wrote. "The attack was practically verified for several randomly selected 1024-bit RSA keys and for several selected 2048-bit keys."
They said a remote attacker could compute an RSA private key from the value of a public key. "The private key can be misused for impersonation of a legitimate owner, decryption of sensitive messages, forgery of signatures (such as for software releases) and other related attacks.
"The actual impact of the vulnerability depends on the usage scenario, availability of the public keys and the lengths of keys used. We found and analysed vulnerable keys in various domains including electronic citizen documents, authentication tokens, trusted boot devices, software package signing, TLS/HTTPS keys and PGP. The currently confirmed number of vulnerable keys found is about 760,000 but possibly up to two to three magnitudes more are vulnerable."
They said they had made available tools for testing for vulnerable keys:
Offline testers: Python/Java/C++ applications and tutorials. All offline tools are under the MIT licence so they can be embedded into other testing applications and services.
Email S-MIME/PGP tester: Send a signed email to firstname.lastname@example.org to obtain an automatic email response with the analysis of the signing key vulnerability.
Tyler Moffitt, a senior threat researcher at security firm Webroot, said the flaw was discovered in the generation of RSA keys used by a software library (RSA Library version v1.02.013) which is adopted in cryptographic smartcards, security tokens and other secure hardware chips.
"The software and hardware containing these flaws has been used for national identity cards, software- and application-signing, and trusted platform modules protecting government and corporate computers for companies like tech giants Google and Microsoft," he told iTWire.
"This five-year-old vulnerability completely breaks the general use and security of using public key cryptography since you're supposed to be able to share your public key without any risk.
"Now any attacker can take your public key and find out the private key which allows them to commit identity theft. Those currently using these crypto identity cards can re-apply for e-Residency or follow other options as disclosed by the officials.”