Biblio
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2021. Cross Layer Attacks and How to Use Them (for DNS Cache Poisoning, Device Tracking and More). 2021 IEEE Symposium on Security and Privacy (SP). :1179–1196.
We analyze the prandom pseudo random number generator (PRNG) in use in the Linux kernel (which is the kernel of the Linux operating system, as well as of Android) and demonstrate that this PRNG is weak. The prandom PRNG is in use by many "consumers" in the Linux kernel. We focused on three consumers at the network level – the UDP source port generation algorithm, the IPv6 flow label generation algorithm and the IPv4 ID generation algorithm. The flawed prandom PRNG is shared by all these consumers, which enables us to mount "cross layer attacks" against the Linux kernel. In these attacks, we infer the internal state of the prandom PRNG from one OSI layer, and use it to either predict the values of the PRNG employed by the other OSI layer, or to correlate it to an internal state of the PRNG inferred from the other protocol.Using this approach we can mount a very efficient DNS cache poisoning attack against Linux. We collect TCP/IPv6 flow label values, or UDP source ports, or TCP/IPv4 IP ID values, reconstruct the internal PRNG state, then predict an outbound DNS query UDP source port, which speeds up the attack by a factor of x3000 to x6000. This attack works remotely, but can also be mounted locally, across Linux users and across containers, and (depending on the stub resolver) can poison the cache with an arbitrary DNS record. Additionally, we can identify and track Linux and Android devices – we collect TCP/IPv6 flow label values and/or UDP source port values and/or TCP/IPv4 ID fields, reconstruct the PRNG internal state and correlate this new state to previously extracted PRNG states to identify the same device.
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2019. Analysis of Key Randomness in Improved One-Time Pad Cryptography. 2019 IEEE 13th International Conference on Anti-counterfeiting, Security, and Identification (ASID). :11–16.
In cryptography, one-time pad (OTP) is claimed to be the perfect secrecy algorithm in several works if all of its features are applied correctly. Its secrecy depends mostly on random keys, which must be truly random and unpredictable. Random number generators are used in key generation. In Psuedo Random Number Generator (PRNG), the possibility of producing numbers that are predictable and repeated exists. In this study, a proposed method using True Random Number Generator (TRNG) and Fisher-Yates shuffling algorithm are implemented to generate random keys for OTP. Frequency (monobit) test, frequency test within a block, and runs tests are performed and showed that the proposed method produces more random keys. Sufficient confusion and diffusion properties are obtained using Pearson correlation analysis.