A team of academics has unveiled a new cryptographic attack this week that can crack TLS-encrypted traffic, allowing attackers to monitor and steal data that was previously considered secure.
This new attack doesn't have a fancy name like most attacks tend to have cryptographys, but it still seems to work on the latest version of the TLS protocol, TLS 1.3, that released it last spring and is considered the safest.
The new cryptographic attack on TLS is not new, but another variant of the original Bleichenbacher attack.
The original attack was named after the Swiss cryptographer Daniel Bleichenbacher, who in 1998 introduced a first attack against systems that used RSA encryption in conjunction with the PKCS # 1 v1 encoding function.
Over the years, cryptographers have made several variations on the original attack, as you can see in the links below: 2003, 2012, 2012, 2014, 2014, 2014, 2015, 2016 (DROWN), 2017 (ROBOT)And 2018.
The reason for all these variations of the attack is because the authors of the TLS encryption protocol decided to add countermeasures to make it more difficult to guess the RSA decryption key, instead of completely replacing the insecure RSA algorithm.
These countermeasures are described in section 7.4.7.1 of the TLS standard (RFC 5246), which many hardware manufacturers and software developers have misinterpreted or not followed exactly the steps it sets out.
The latest variants of the Bleichenbacher attack were described in a white paper published last Wednesday: “The 9 Lives of CAT Bleichenbacher: New Sneak Attacks μνήμηs in the TLS application” in Greek and “The 9 Lives of Bleichenbacher's CAT: New Cache ATtacks on TLS Implementations” ο αυθεντικός τίτλος του pdf.
Seven researchers from around the world have discovered (again) another way to break RSA PKCS # 1 v1.5, the most common RSA configuration used to encrypt TLS connections today.
In addition to breaking the TLS, the new Bleichenbacher attack works perfectly for Google's new QUIC encryption protocol.
"The attack exploits a leakage side channels through timings accessof the cache to crack RSA key exchanges of TLS applications,” the researchers report.
Even the latest version of the TLS 1.3 protocol, where the use of RSA has been kept to a minimum, can be downgraded to TLS 1.2, where the new variant of the Bleichenbacher attack operates.
"We tested nine different TLS applications and all seven were found to be vulnerable: OpenSSL, Amazon s2n, MbedTLS, Apple CoreTLS, Mozilla NSS, WolfSSLAnd GnuTLS", Say the researchers.
Updates of all libraries affected by the attack were published simultaneously in November 2018, when the researchers published an initial draft of their research.
For more details, there are the following CVEs: CVE-2018-12404, CVE-2018-19608, CVE-2018-16868, CVE-2018-16869 and CVE-2018-16870.
The two libraries that were not found to be vulnerable are BearSSL and Google BoringSSL.