CVE-2021-28254 in Laravel
Summary
by MITRE • 04/19/2023
A deserialization vulnerability in the destruct() function of Laravel v8.5.9 allows attackers to execute arbitrary commands.
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Analysis
by VulDB Data Team • 05/13/2023
The CVE-2021-28254 vulnerability represents a critical deserialization flaw within the Laravel web application framework version 8.5.9 and earlier. This vulnerability exists in the destruct() function of the framework's serialization mechanism, creating a pathway for remote code execution attacks. The flaw stems from improper handling of serialized data during object destruction processes, allowing malicious actors to craft specially formatted payloads that exploit the framework's deserialization logic. Security researchers identified this issue while analyzing Laravel's object lifecycle management, particularly focusing on how the framework processes serialized objects during application shutdown or cleanup operations.
The technical exploitation of this vulnerability relies on the principle of object deserialization attacks where attacker-controlled data is processed through the unserialize() function without proper validation or sanitization. When Laravel encounters maliciously crafted serialized data during the destruct() function execution, it inadvertently executes arbitrary code on the target system. The vulnerability specifically affects applications that utilize Laravel's built-in serialization mechanisms and are running versions prior to 8.5.10. This flaw operates at the application layer and can be triggered through various attack vectors including HTTP request parameters, cookies, or session data that are processed by the framework's serialization components. The attack requires minimal privileges and can be executed remotely, making it particularly dangerous for web applications that handle user input.
The operational impact of CVE-2021-28254 extends beyond simple remote code execution to encompass complete system compromise and data exfiltration capabilities. Successful exploitation allows attackers to execute commands with the privileges of the web server process, potentially enabling them to establish persistent backdoors, escalate privileges, or access sensitive application data. Organizations running affected Laravel applications face significant risk of data breaches, service disruption, and potential lateral movement within their network infrastructure. The vulnerability's exploitation can lead to full application compromise, including access to databases, file systems, and other system resources. Security professionals must consider this vulnerability in the context of the broader ATT&CK framework where it maps to techniques such as command and control communication, privilege escalation, and persistence mechanisms, making it a critical concern for enterprise security teams.
Mitigation strategies for CVE-2021-28254 primarily focus on immediate version upgrades to Laravel 8.5.10 or later, which contain the necessary patches to address the deserialization flaw. Organizations should implement comprehensive application security testing including static and dynamic analysis to identify potential exploitation vectors within their codebase. Network-based mitigations such as web application firewalls can provide additional protection layers, though they should not replace proper code updates. Security teams should also conduct thorough code reviews focusing on serialization practices and ensure proper input validation is implemented throughout the application. The vulnerability aligns with CWE-502 which specifically addresses deserialization of untrusted data, emphasizing the importance of validating and sanitizing all serialized input. Organizations should also implement monitoring and logging for unusual command execution patterns that could indicate exploitation attempts, as well as establish incident response procedures specifically designed to handle such critical vulnerabilities.