CVE-2017-5638 in WebLogic Server
Summary
by MITRE
The Jakarta Multipart parser in Apache Struts 2 2.3.x before 2.3.32 and 2.5.x before 2.5.10.1 has incorrect exception handling and error-message generation during file-upload attempts, which allows remote attackers to execute arbitrary commands via a crafted Content-Type, Content-Disposition, or Content-Length HTTP header, as exploited in the wild in March 2017 with a Content-Type header containing a #cmd= string.
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Analysis
by VulDB Data Team • 12/25/2024
The vulnerability identified as CVE-2017-5638 represents a critical remote code execution flaw within Apache Struts 2 frameworks version 2.3.x prior to 2.3.32 and 2.5.x prior to 2.5.10.1. This vulnerability specifically targets the Jakarta Multipart parser implementation that handles file upload operations, making it particularly dangerous for web applications that process user-uploaded content. The flaw was actively exploited in the wild during March 2017, demonstrating its real-world impact and the urgency of immediate remediation efforts. Security researchers have classified this vulnerability under CWE-94, which describes "Improper Control of Generation of Code" as the underlying weakness, indicating that the system fails to properly control the generation or execution of code during multipart parsing operations.
The technical mechanism of exploitation involves manipulating HTTP headers, specifically the Content-Type, Content-Disposition, or Content-Length fields, to inject malicious payloads that trigger command execution on the affected server. When a crafted Content-Type header containing a #cmd= string is processed by the vulnerable Struts framework, the multipart parser incorrectly handles the exception and generates an error message that inadvertently executes arbitrary commands. This occurs because the framework's error handling mechanism fails to properly sanitize user input before processing, allowing attackers to inject operating system commands that get executed with the privileges of the web application server. The vulnerability operates at the application layer and requires no authentication, making it particularly dangerous as it can be exploited by anyone who can send HTTP requests to the target system.
The operational impact of CVE-2017-5638 extends beyond simple remote code execution to encompass complete system compromise and potential data breaches. Attackers who successfully exploit this vulnerability can gain full control over the affected web server, enabling them to install backdoors, exfiltrate sensitive data, modify application behavior, or use the compromised server as a launch point for further attacks within the network. The widespread adoption of Apache Struts 2 across enterprise applications and web platforms means that a single vulnerable instance could provide attackers with access to critical business systems, customer databases, and internal network resources. Organizations running vulnerable versions of Struts 2 were particularly at risk during the initial exploitation wave, as the vulnerability allowed attackers to bypass traditional security controls and gain direct access to server infrastructure.
Mitigation strategies for CVE-2017-5638 primarily focus on immediate patching and implementation of additional security controls. Organizations must upgrade to Apache Struts 2 versions 2.3.32 or 2.5.10.1, which contain the necessary fixes for the multipart parser vulnerability. Additionally, implementing web application firewalls with rules to detect and block suspicious Content-Type headers containing command injection patterns can provide interim protection. Security teams should also consider implementing input validation controls that sanitize HTTP headers before they reach the Struts framework, as well as monitoring for unusual patterns in file upload operations and error message generation. The vulnerability's exploitation aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically targeting Windows Command Shell, and demonstrates the importance of proper input validation and secure coding practices in preventing such critical security flaws. Organizations should conduct comprehensive vulnerability assessments to identify all instances of affected Struts versions and implement layered security approaches to reduce the attack surface and prevent similar vulnerabilities from being exploited in the future.