CVE-2021-28037 in internment Crate
Summary
by MITRE • 03/05/2021
An issue was discovered in the internment crate before 0.4.2 for Rust. There is a data race that can cause memory corruption because of the unconditional implementation of Sync for Intern.
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Analysis
by VulDB Data Team • 03/07/2021
The vulnerability identified as CVE-2021-28037 affects the internment crate version 0.4.2 and earlier in the Rust programming language ecosystem. This issue stems from a fundamental concurrency flaw within the crate's design that undermines memory safety guarantees. The internment crate is designed to provide efficient string interning capabilities, allowing multiple references to identical strings to share the same memory location. However, the implementation contains a critical flaw that manifests when the Sync trait is unconditionally implemented for the Intern type, creating a dangerous data race condition.
The technical root cause of this vulnerability lies in the improper handling of shared mutable state within concurrent environments. When the Sync trait is implemented without proper synchronization mechanisms, multiple threads can simultaneously access and modify the same interned data structures, leading to unpredictable memory corruption patterns. This occurs because the internment crate fails to account for the fact that interned strings may be accessed concurrently by different threads, yet provides no protective measures against such scenarios. The data race vulnerability specifically manifests when multiple threads attempt to read and write to the same interned string storage simultaneously, causing the memory layout to become corrupted.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling arbitrary code execution or system instability in applications that rely on the internment crate for string management. Attackers could exploit this weakness by crafting specific concurrent access patterns that trigger the data race conditions, leading to memory corruption that might be leveraged for privilege escalation or denial of service attacks. Applications using the affected crate in multi-threaded environments are particularly at risk, as the vulnerability becomes more pronounced under high-concurrency workloads where thread contention increases. The flaw affects the fundamental memory safety guarantees that Rust developers expect, undermining the language's core security properties.
Mitigation strategies for this vulnerability require immediate action to upgrade to version 0.4.2 or later of the internment crate where the data race has been properly addressed. Developers should also review their codebases for any direct or indirect dependencies on the vulnerable crate and ensure all components are updated accordingly. The fix typically involves implementing proper synchronization mechanisms such as mutexes or atomic operations to protect shared interned data structures, or alternatively removing the unconditional Sync implementation and requiring explicit synchronization from users of the crate. Security teams should prioritize this vulnerability in their assessment processes, particularly for applications handling sensitive data or operating in multi-threaded environments. Organizations using Rust-based systems should also consider implementing additional monitoring for memory corruption patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-362, which describes concurrent execution using shared data without proper synchronization, and could potentially map to ATT&CK technique T1059.007 for code injection via memory corruption vulnerabilities.
The broader implications of this vulnerability highlight the critical importance of careful concurrency design in systems programming languages like Rust. Memory safety issues in core libraries can have cascading effects across entire application ecosystems, as demonstrated by the potential for this single flaw to compromise multiple dependent applications. This case underscores the necessity for comprehensive testing of concurrent scenarios in library development and the importance of adhering to established security practices in systems programming. The vulnerability serves as a reminder that even seemingly simple utility crates can contain fundamental flaws that compromise system integrity when deployed in production environments.