CVE-2019-15549 in asn1_der Crate
Summary
by MITRE
An issue was discovered in the asn1_der crate before 0.6.2 for Rust. Attackers can trigger memory exhaustion by supplying a large value in a length field.
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Analysis
by VulDB Data Team • 12/04/2023
The vulnerability identified as CVE-2019-15549 resides within the asn1_der crate version 0.6.1 and earlier of the rust programming language ecosystem. This issue represents a critical memory exhaustion flaw that can be exploited through crafted input data containing oversized length fields. The asn1_der crate serves as a fundamental component for handling asn1.1 der encoded data structures in rust applications, making this vulnerability particularly concerning for systems that process structured data from untrusted sources. The flaw manifests when the crate encounters a length field containing an excessively large value, which triggers improper memory allocation behavior during the parsing process.
The technical implementation of this vulnerability stems from inadequate input validation within the asn1_der parsing logic. When processing asn1.1 der encoded data, the crate reads length fields to determine how much memory to allocate for subsequent data parsing operations. Attackers can manipulate these length fields to specify memory requirements that far exceed available system resources, causing the application to allocate massive amounts of memory or potentially trigger memory exhaustion conditions. This behavior aligns with CWE-770, which specifically addresses allocation of resources without proper limits or checks, and represents a classic example of an unchecked resource consumption vulnerability. The flaw operates at the parsing layer where the crate fails to validate that length fields fall within reasonable bounds before attempting memory allocation.
The operational impact of CVE-2019-15549 extends beyond simple denial of service scenarios, as it can potentially lead to system instability and resource exhaustion across multiple applications. Systems utilizing the affected crate may experience complete service unavailability when processing maliciously crafted data, as the memory exhaustion can cause the application to crash or become unresponsive. This vulnerability is particularly dangerous in network-facing applications or services that process data from external sources, as attackers can exploit it to consume system resources and potentially cause cascading failures. The attack vector requires minimal sophistication, making it accessible to threat actors across different skill levels and increasing the overall risk exposure for affected systems.
Mitigation strategies for CVE-2019-15549 primarily focus on updating to the patched version 0.6.2 of the asn1_der crate, which implements proper bounds checking for length fields during parsing operations. Security teams should prioritize patching all affected applications and systems that utilize this crate, particularly those handling untrusted data inputs. Additional protective measures include implementing input validation layers, establishing memory limits for parsing operations, and monitoring for unusual memory consumption patterns. Organizations should also consider implementing network segmentation and access controls to limit exposure of vulnerable services to untrusted networks. The vulnerability demonstrates the importance of proper resource management in cryptographic libraries and reinforces the need for comprehensive security testing of parsing components. This issue highlights the ATT&CK technique of resource exhaustion and can be classified under the broader category of denial of service attacks that leverage memory consumption vulnerabilities.