CVE-2020-7719 in locutus Package
Summary
by MITRE
All versions of package locutus are vulnerable to Prototype Pollution via the php.strings.parse_str function.
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Analysis
by VulDB Data Team • 11/12/2020
The vulnerability identified as CVE-2020-7719 affects the locutus package, a JavaScript implementation of PHP functions, where the php.strings.parse_str function exhibits prototype pollution behavior. This flaw allows attackers to manipulate the prototype of JavaScript objects through malicious input, potentially leading to arbitrary code execution or other security implications. The vulnerability exists in all versions of the package and represents a critical security risk for applications that utilize this library.
Prototype pollution occurs when an application fails to properly validate or sanitize user input that is used to modify object properties, particularly those that affect the Object prototype. In the context of the locutus package, the php.strings.parse_str function processes query string parameters and directly assigns them to object properties without adequate protection against prototype manipulation. This vulnerability falls under the Common Weakness Enumeration category CWE-471, which specifically addresses the weakness of using an unsafe function that can lead to prototype pollution attacks.
The operational impact of this vulnerability extends beyond simple data corruption, as it can enable attackers to inject malicious properties into the Object prototype itself. When applications parse user-supplied data through this function, an attacker can craft specially formatted input that modifies the prototype of objects, potentially causing the application to behave unexpectedly or execute unintended code. This type of vulnerability is particularly dangerous in server-side environments where the parsed data might be processed through subsequent functions that rely on prototype properties.
Security researchers have documented that prototype pollution vulnerabilities can be exploited in various attack scenarios including but not limited to bypassing security controls, causing denial of service conditions, or enabling more sophisticated attacks such as prototype chain poisoning. The ATT&CK framework categorizes this type of vulnerability under the T1553.003 technique, which involves bypassing security controls through the manipulation of object prototypes. Applications using the vulnerable locutus package may be susceptible to attacks where malicious input can alter the behavior of core JavaScript functions.
Mitigation strategies for this vulnerability require immediate action including updating to the latest version of the locutus package where the prototype pollution issue has been addressed. Organizations should also implement input validation and sanitization measures to prevent malicious data from reaching the vulnerable parse_str function. Additionally, developers should consider implementing prototype pollution protection mechanisms such as using Object.freeze() or Object.preventExtensions() on critical objects, and employing security libraries designed to detect and prevent prototype pollution attacks. The vulnerability underscores the importance of thorough security testing and validation of third-party libraries, particularly those handling user input or implementing language translation functions that may be susceptible to such attacks.
The broader implications of this vulnerability highlight the need for security awareness in JavaScript development environments, where prototype manipulation can have cascading effects throughout an application's functionality. Given that the locutus package is often used to provide PHP compatibility in JavaScript environments, the vulnerability demonstrates how cross-language compatibility libraries can introduce unexpected security risks that require careful monitoring and validation.