An issue was discovered in the atom crate before 0.3.6 for Rust. An unsafe Send implementation allows a cross-thread data race.
**The atom crate vulnerability (CVE-2020-35897) in Rust allows for a cross-thread data race, potentially leading to arbitrary code execution and system compromise. This flaw, stemming from an unsafe Send implementation, enables attackers to manipulate shared memory across threads, creating a window for exploitation. Successful exploitation could result in data theft, denial of service, or complete system takeover.
Step 1: Target Identification: The attacker identifies a Rust application that uses the vulnerable version of the atom crate.
Step 2: Payload Injection: The attacker crafts a malicious payload that leverages the atom crate's unsafe Send implementation. This payload is designed to trigger a data race.
Step 3: Thread Creation: The attacker's payload creates multiple threads within the target application.
Step 4: Shared Data Manipulation: The threads concurrently access and modify shared data structures managed by the vulnerable atom crate, exploiting the lack of synchronization.
Step 5: Race Condition Trigger: The concurrent access and modification of shared data triggers a race condition, leading to unpredictable behavior.
Step 6: Exploitation: The attacker's payload exploits the race condition to achieve a desired outcome, such as memory corruption, data corruption, or arbitrary code execution.
Step 7: Code Execution/Data Exfiltration: If successful, the attacker gains control of the application or exfiltrates sensitive data.
The root cause of CVE-2020-35897 lies in the atom crate's implementation of the Send trait. The Send trait in Rust is used to indicate that a type can be safely sent between threads. The vulnerability arises because the atom crate, prior to version 0.3.6, incorrectly implemented the Send trait for certain types, despite not guaranteeing thread safety. This means that data structures managed by the atom crate could be shared across threads without proper synchronization mechanisms (e.g., mutexes, atomic operations). This lack of synchronization creates a race condition. When multiple threads access and modify the same data concurrently without proper locking, the final state of the data becomes unpredictable, leading to potential data corruption, memory corruption, or even arbitrary code execution. The unsafe Send implementation allows for concurrent access to shared mutable state, violating Rust's memory safety guarantees and opening the door to exploitation. The specific logic flaw is the absence of appropriate synchronization primitives when sharing data across threads, leading to a data race.