CVE-2017-15871 in serialize-to-js Package
Summary
by MITRE
** DISPUTED ** The deserialize function in serialize-to-js through 1.1.1 allows attackers to bypass intended access restrictions via vectors involving a "function()" substring, as demonstrated by a "function(){console.log(" call. NOTE: The vendor states 'In my understanding [this attack] just runs inside a "sandbox" and prints ... to a tty.'
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2017-15871 resides within the serialize-to-js library version 1.1.1 and earlier, representing a significant security flaw that could potentially allow unauthorized code execution. This issue manifests through the deserialize function's handling of serialized data structures, specifically when processing inputs containing function() substrings. The vulnerability has been marked as disputed by the vendor, who argues that the attack merely executes within a sandboxed environment and only produces output to a terminal interface rather than causing actual system compromise.
The technical flaw exploits the library's deserialization process by manipulating serialized data that includes function() patterns, enabling attackers to inject malicious code that bypasses intended access controls. When the deserialize function processes such inputs, it fails to properly validate or sanitize the content, allowing arbitrary JavaScript code execution within the context where the deserialization occurs. This behavior creates a potential attack vector where an attacker could craft serialized payloads containing function() substrings that would be executed during the deserialization process, effectively circumventing the library's intended security boundaries.
The operational impact of this vulnerability extends beyond simple code execution, as it represents a critical weakness in data serialization and deserialization security practices. Attackers could potentially leverage this flaw to execute arbitrary commands or access restricted resources within applications that utilize the vulnerable library. The sandboxed execution model described by the vendor, while limiting the scope of potential damage, still presents a significant risk since it allows for information disclosure, denial of service, and potential escalation of privileges within the application's execution environment. This vulnerability directly relates to common weakness enumerations such as CWE-502, which addresses deserialization of untrusted data, and aligns with attack patterns found in the ATT&CK framework under the execution and privilege escalation domains.
Mitigation strategies for CVE-2017-15871 should focus on immediate library updates to versions that address the deserialization vulnerability, along with comprehensive code review processes to identify any potential usage patterns that might expose applications to similar risks. Organizations should implement strict input validation and sanitization measures for all serialized data, particularly when dealing with user-provided content. The recommended approach includes upgrading to newer versions of the serialize-to-js library where the vulnerability has been patched, implementing proper access controls and sandboxing mechanisms, and conducting thorough security testing of applications that utilize serialization functions. Additionally, developers should consider alternative serialization methods that do not rely on JavaScript eval or function construction, and implement proper security controls that prevent execution of untrusted code within the application's execution context. The vulnerability highlights the importance of proper input validation and the dangers of executing untrusted serialized data without adequate sanitization measures.