This 5-year-old algorithmic vulnerability was discovered by security researchers at Masaryk University in the Czech Republic, who have released a blog post with more details about the weakness as well as an online tool to test if RSA keys are vulnerable to this dangerous flaw.
ROCA: Factorization Attack to Recover Private RSA Keys
Dubbed ROCA (Return of Coppersmith's Attack), the factorization attack introduced by the researchers could potentially allow a remote attacker to reverse-calculate a private encryption key just by having a target's public key—thanks to this bug.
"Only the knowledge of a public key is necessary and no physical access to the vulnerable device is required," the researchers said. "The vulnerability does NOT depend on a weak or a faulty random number generator—all RSA keys generated by a vulnerable chip are impacted."This could eventually allow the attacker to impersonate key owner, decrypt victim's sensitive data, inject malicious code into digitally signed software, and bypass protections that prevent accessing or tampering with the targeted computer.
ROCA Attack Exposes Billions of Devices to Attack
"We found and analyzed vulnerable keys in various domains including electronic citizen documents, authentication tokens, trusted boot devices, software package signing, TLS/HTTPS keys and PGP," the researchers said.
"The currently confirmed number of vulnerable keys found is about 760,000 but possibly up to two to three magnitudes more are vulnerable."
More Details, Testing Tool, and Patches
The security researchers have released a brief blog post about the flaw, which includes a number of tools for detection, mitigation and workarounds. The vulnerability was discovered and reported to Infineon Technologies in February this year and the researchers will present their full findings, including the factorization method, on November 2nd at the ACM Conference on Computer and Communications Security.
Their research paper, titled "The Return of Coppersmith's Attack: Practical Factorization of Widely Used RSA Moduli" (ROCA), will also be released after their presentation.So, companies and organisations have enough time to change affected encryption keys before the details of how this vulnerability works and could be exploited are released.
Major vendors including Infineon, Microsoft, Google, HP, Lenovo, and Fujitsu have already released the software updates for their relevant hardware and software as well as guidelines for a mitigation of this vulnerability.
"Some Windows security features and potentially third-party software rely on keys generated by the TPM (if available on the system)," according to a Microsoft advisory. "Microsoft is releasing Windows security updates to help work around the vulnerability by logging events and by allowing the generation of software based keys."Therefore, users are strongly recommended to patch their devices as soon as possible—AGAIN!