CVE-2020-24807 in socket.io-file
Summary
by MITRE • 10/06/2020
** UNSUPPORTED WHEN ASSIGNED ** The socket.io-file package through 2.0.31 for Node.js relies on client-side validation of file types, which allows remote attackers to execute arbitrary code by uploading an executable file via a modified JSON name field. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/04/2024
The socket.io-file package version 2.0.31 and earlier contains a critical security flaw that stems from improper validation of file types on the client-side only. This vulnerability represents a classic example of insufficient input validation and server-side trust assumptions, where the system relies entirely on client-provided information to make security decisions. The flaw exists in the package's handling of file uploads through the socket.io protocol, specifically in how it processes the JSON name field that contains file metadata. When an attacker crafts a malicious file upload request with a modified JSON name field, the system accepts this information without proper server-side verification, creating a dangerous attack vector.
This vulnerability is categorized as a code execution flaw that operates through a client-side validation bypass mechanism. The attack occurs when an attacker uploads an executable file by manipulating the JSON name field to disguise the file type, fooling the system into accepting potentially malicious content. The vulnerability stems from a fundamental security principle violation where the server trusts client-side validation entirely, allowing attackers to circumvent security measures that should be enforced server-side. This type of flaw commonly maps to CWE-20, which describes "Improper Input Validation" in software security, and represents a clear case of trust boundary violation where client data is not properly sanitized before being processed.
The operational impact of this vulnerability is severe and potentially catastrophic for systems using the affected package. Remote attackers can execute arbitrary code on vulnerable systems with the privileges of the Node.js process, which could lead to complete system compromise, data exfiltration, or service disruption. The vulnerability is particularly dangerous because it allows attackers to upload and execute malicious executables, which could include backdoors, malware, or other malicious payloads. The attack requires minimal privileges and can be performed remotely, making it highly attractive to threat actors. Systems that rely on socket.io-file for file sharing or upload functionality become immediately vulnerable to this type of attack, especially in environments where file uploads are not properly restricted or monitored.
Security mitigations for this vulnerability are limited due to the package being unsupported, but organizations should implement several defensive measures to reduce risk. The primary mitigation involves implementing robust server-side file validation that does not rely on client-provided metadata, including checking file extensions, content type signatures, and file headers rather than trusting the JSON name field. Organizations should also implement proper file upload restrictions, such as limiting file types to known safe formats, implementing file size limits, and using secure file storage practices. Additionally, network-level controls such as firewall rules and intrusion detection systems can help monitor and block suspicious file upload activities. The vulnerability aligns with ATT&CK technique T1059 which covers "Command and Scripting Interpreter" and T1078 which covers "Valid Accounts" as attackers may use compromised systems to execute malicious code and maintain persistence. Given the unsupported status of the package, the most effective long-term solution is to migrate to supported alternatives with proper security controls, implement comprehensive file upload validation at multiple layers, and conduct thorough security reviews of all file handling components in the application stack.