CVE-2020-13622 in JerryScript
Summary
by MITRE
JerryScript 2.2.0 allows attackers to cause a denial of service (assertion failure) because a property key query for a Proxy object returns unintended data.
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Analysis
by VulDB Data Team • 05/28/2020
The vulnerability identified as CVE-2020-13622 affects JerryScript version 2.2.0, a lightweight javascript engine designed for embedded systems and IoT devices. This issue manifests as a denial of service condition triggered by an assertion failure within the engine's handling of Proxy objects. The flaw occurs during property key queries where the engine returns unintended data instead of properly managing the proxy's internal state. Such behavior represents a critical weakness in the javascript engine's object model implementation, particularly in how it processes proxy objects that are used to define custom behavior for fundamental operations. The vulnerability demonstrates a fundamental flaw in the engine's ability to maintain consistent internal state during proxy operations, which can lead to unpredictable behavior and system instability.
The technical root cause of this vulnerability lies in the improper handling of property key queries within Proxy objects, specifically when the engine attempts to retrieve property keys from a proxy target. According to CWE-691, this represents an insufficient control flow management issue where the engine fails to properly validate or handle the return values from proxy operations. The assertion failure occurs because the engine's internal checks expect specific data types or structures that are not consistently provided when dealing with certain proxy configurations. This type of vulnerability falls under the ATT&CK technique T1499.004, which involves network disruption through resource exhaustion or system instability, as the denial of service condition can be triggered by maliciously crafted javascript code that manipulates proxy objects.
The operational impact of this vulnerability extends beyond simple system instability to potentially compromise the integrity of applications that rely on JerryScript for execution. In embedded environments where JerryScript is commonly deployed, such as smart home devices, industrial control systems, or network appliances, an attacker could exploit this vulnerability to cause persistent service disruption. The vulnerability is particularly concerning because it affects the core javascript engine functionality, meaning that any application utilizing proxy objects or property key queries could become vulnerable. The assertion failure creates a condition where the engine terminates abnormally, leading to complete service unavailability. This type of vulnerability can be particularly dangerous in critical infrastructure environments where system uptime is essential for safety and operational continuity.
Mitigation strategies for CVE-2020-13622 should focus on immediate software updates to versions that address the proxy handling logic. System administrators should prioritize updating JerryScript installations to versions that contain proper validation and handling of proxy property key queries. Additionally, implementing input validation and sanitization measures can help reduce the attack surface by preventing malicious proxy configurations from being processed. Organizations should also consider deploying runtime monitoring solutions that can detect anomalous proxy behavior patterns and alert on potential exploitation attempts. The vulnerability highlights the importance of proper testing and validation of javascript engine features, particularly those involving complex object model interactions like Proxy objects. Security teams should also implement regular vulnerability assessments and penetration testing to identify similar issues in other embedded javascript engines or similar software components that may exhibit similar behavioral patterns.