A new high-precision branch target injection (BTI) attack called “Indirector” has been discovered by security researchers at the University of California, San Diego. This vulnerability affects modern Intel processors, including Raptor Lake and Alder Lake CPUs. The attack exploits vulnerabilities within the Indirect Branch Predictor (IBP) and the Branch Target Buffer (BTB) to hijack execution and leak sensitive data, bypassing existing protection mechanisms. Indirector will be discussed in detail at the upcoming USENIX Security Symposium in August 2024.
Branch prediction is a crucial technique used by CPUs to anticipate program execution flow, improving efficiency. BTI attacks manipulate branch prediction features to execute speculative code, similar to previous attacks like Spectre and Collapse. These attacks target vulnerabilities in CPUs to gain unauthorized access to sensitive data. Despite existing defenses like Indirect Branching Predictive Barriers (IBPB), new attack vectors continue to exploit CPU vulnerabilities, as demonstrated by the Indirector attack.
To mitigate BTI attacks, it is crucial to implement barriers like the Indirect Branching Predictor Barrier (IBPB) and strengthen the design of the Branch Prediction Unit (BPU) with complex labels, encryption, and randomization. IBPB invalidates indirect branch predictions during context switches but can impact performance. Future BPU designs should integrate more advanced techniques to enhance security.
The Indirector attack highlights the evolving threat landscape against modern CPUs. Despite existing security measures, the complexity and sophistication of CPUs provide avenues for attackers. Side-channel vulnerabilities remain a persistent threat, emphasizing the need for continued research and improvement in hardware and software defenses to protect against BTI attacks.
The RHC Dark Lab, led by Pietro Melillo, is a community think tank dedicated to cyber threat intelligence. The lab aims to disseminate knowledge on cyber threats and improve awareness and defenses against digital threats. By involving specialists and the general public, the lab seeks to anticipate and mitigate cyber threats through intelligence sharing.
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