Finally, we used the reduced set to scan at scale, and clustered our findings with a novel approach using graph drawing algorithms.Ĭontrary to common wisdom, exploiting CBC padding oracles does not necessarily require performing precise timing measurements.

We then reduced the number of probes using a preliminary scan, such that a smaller set of probes has the same detection rate but is small enough to be used in large-scale scans. First, we created a large set of probes that detect vulnerabilities at a considerable scanning cost. We used a novel scanning methodology consisting of three steps. Our scanner observes subtle differences in server behavior, such as responding with different TLS alerts, or with different TCP header flags. Our scan revealed vulnerabilities in 1.83% of the Alexa Top Million websites, detecting nearly 100 different vulnerabilities. We present the first large-scale scan for CBC padding oracle vulnerabilities in TLS implementations on the modern Internet. These attacks allow an adversary to decrypt TLS traffic by observing different server behaviors which depend on the validity of CBC padding. One prominent class of such attacks is CBC padding oracle attacks. Despite the protocol's importance, currently-deployed TLS versions use obsolete cryptographic algorithms which have been broken using various attacks. The TLS protocol provides encryption, data integrity, and authentication on the modern Internet. We were able to successfully recover the PreMasterSecret using three of the four side channels in a realistic measurement setup. Our measurements confirmed that all these side channels are observable over a switched network, with timing differences between 1 and 23 microseconds. Three of these side channels are timingbased, and two of them provide the first timing-based Bleichenbacher attacks on SSL/TLS described in the literature. Table 1): We present four new Bleichenbacher side channels, and three successful Bleichenbacher attacks against the Java Secure Socket Extension (JSSE) SSL/TLS implementation and against hardware security appliances using the Cavium NITROX SSL accelerator chip. In this paper we show that this objective has not been achieved yet (cf. As a countermeasure against the famous Bleichenbacher attack on RSA based ciphersuites, all TLS RFCs starting from RFC 2246 (TLS 1.0) propose “to treat incorrectly formatted messages in a manner indistinguishable from correctly formatted RSA blocks”.

Java se development kit 6u37