CVE-2016-6793 in Wicket
Summary
by MITRE
The DiskFileItem class in Apache Wicket 6.x before 6.25.0 and 1.5.x before 1.5.17 allows remote attackers to cause a denial of service (infinite loop) and write to, move, and delete files with the permissions of DiskFileItem, and if running on a Java VM before 1.3.1, execute arbitrary code via a crafted serialized Java object.
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Analysis
by VulDB Data Team • 10/27/2022
The vulnerability identified as CVE-2016-6793 resides within the DiskFileItem class of Apache Wicket framework, a popular Java web application framework used for building dynamic web applications. This flaw affects versions 6.x prior to 6.25.0 and 1.5.x prior to 1.5.17, representing a critical security issue that extends beyond simple denial of service to encompass potential remote code execution capabilities. The vulnerability stems from improper handling of serialized Java objects during file processing operations, creating a dangerous attack surface for malicious actors seeking to compromise affected systems.
The technical exploitation of this vulnerability occurs through crafted serialized Java objects that manipulate the DiskFileItem class behavior during file upload operations. When a maliciously crafted object is processed, it can trigger an infinite loop that consumes system resources and leads to denial of service conditions. Additionally, the vulnerability allows attackers to perform file system operations including writing, moving, and deleting files using the permissions associated with the DiskFileItem process. This represents a significant privilege escalation risk since the affected applications typically run with elevated system permissions. The vulnerability becomes even more dangerous when the application runs on Java Virtual Machine versions prior to 1.3.1, where attackers can achieve arbitrary code execution through the serialized object manipulation.
From an operational impact perspective, this vulnerability creates multiple attack vectors that can severely compromise web application security and availability. Organizations running affected Apache Wicket versions face potential complete system compromise, as attackers can not only disrupt services through denial of service but also gain persistent access through arbitrary code execution. The infinite loop mechanism can be exploited to exhaust system resources, potentially causing application crashes or system instability that affects legitimate users. The file system manipulation capabilities allow attackers to modify application files, potentially leading to data corruption, information disclosure, or further privilege escalation attacks.
The vulnerability aligns with CWE-502, which describes "Deserialization of Untrusted Data" as a critical weakness in software security. This classification indicates that the flaw occurs when an application deserializes data from an untrusted source without proper validation, creating opportunities for attackers to manipulate object state during deserialization. The attack patterns associated with this vulnerability map to several ATT&CK techniques including T1059.007 for command and scripting interpreter and T1499.004 for network denial of service. Organizations should implement immediate mitigations including upgrading to patched versions of Apache Wicket, implementing proper input validation for file uploads, and restricting file system permissions for application processes. Network segmentation and monitoring for suspicious deserialization activities should also be implemented to detect potential exploitation attempts.
The remediation strategy focuses primarily on upgrading to Apache Wicket versions 6.25.0 or later and 1.5.17 or later, which contain the necessary patches to address the deserialization vulnerability. Additional protective measures include implementing strict input validation for all file upload operations, configuring proper file system permissions to limit the impact of potential exploitation, and monitoring application logs for unusual file system activities. Security teams should also consider implementing application firewalls or intrusion detection systems that can identify and block suspicious serialized object patterns. Regular security assessments and penetration testing should be conducted to ensure that similar vulnerabilities are not present in other components of the web application stack, particularly given the widespread use of Java serialization in enterprise applications.