CVE-2020-36206 in rusb Crate
Summary
by MITRE • 01/26/2021
An issue was discovered in the rusb crate before 0.7.0 for Rust. Because of a lack of Send and Sync bounds, a data race and memory corruption can occur.
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Analysis
by VulDB Data Team • 02/20/2021
The vulnerability identified as CVE-2020-36206 resides within the rusb crate version 0.6.2 and earlier, representing a critical concurrency flaw that fundamentally undermines memory safety in Rust applications. This issue stems from the absence of proper Send and Sync trait bounds within the crate's design, creating a scenario where multiple threads can simultaneously access and modify shared data structures without adequate synchronization mechanisms. The rusb crate serves as a Rust binding for libusb, enabling applications to communicate with usb devices through direct hardware access, making it particularly dangerous in multi-threaded environments where concurrent device operations are common. The lack of these essential trait bounds means that the compiler cannot guarantee memory safety when the crate's types are shared across thread boundaries, opening the door to undefined behavior that can manifest as data races and subsequent memory corruption.
The technical root cause of this vulnerability aligns with CWE-362, which specifically addresses concurrent execution using shared resource access without proper synchronization controls. When developers use the rusb crate in multi-threaded applications, they inadvertently create conditions where one thread might be reading from or writing to a USB device handle while another thread modifies the same resource, leading to unpredictable behavior and potential system crashes. The absence of Send and Sync bounds prevents the Rust compiler from performing necessary static analysis to detect unsafe concurrent access patterns, effectively bypassing the language's memory safety guarantees. This flaw particularly impacts applications that need to perform asynchronous USB operations or handle multiple device interactions simultaneously, as these scenarios naturally involve concurrent access to shared resources.
The operational impact of CVE-2020-36206 extends beyond simple application instability to potentially enable more severe security consequences. Memory corruption resulting from data races can be exploited by malicious actors to achieve arbitrary code execution, especially when applications using the affected crate process untrusted USB device data or operate in environments where privilege escalation is possible. Attackers could potentially craft USB devices or manipulate existing device interactions to trigger the race conditions, leading to system compromise through buffer overflows or other memory corruption exploits. This vulnerability particularly affects embedded systems, IoT devices, and applications that rely heavily on USB communication, where the combination of multi-threading and hardware interaction creates numerous potential attack vectors.
Mitigation strategies for CVE-2020-36206 primarily involve upgrading to rusb version 0.7.0 or later, where the Send and Sync bounds have been properly implemented to ensure thread safety. System administrators and developers should conduct thorough code reviews to identify any usage patterns that might still create unsafe concurrent access scenarios even with the updated crate. Organizations should implement continuous monitoring for vulnerable dependencies and establish processes for rapid patch deployment across their software ecosystems. The ATT&CK framework categorizes this vulnerability under T1059.007 for system services and T1547.001 for registry run keys, as exploitation might involve modifying system-level USB handling components or creating persistent backdoors through compromised device drivers. Additionally, defensive measures should include runtime protections such as address space layout randomization and stack canaries to detect and prevent exploitation attempts, while also implementing proper input validation and error handling to minimize the impact of any successful attacks on the system's overall integrity.