CVE-2017-3207 in WebORB for Java
Summary
by MITRE
The Java implementations of AMF3 deserializers in WebORB for Java by Midnight Coders, version 5.1.1.0, derive class instances from java.io.Externalizable rather than the AMF3 specification's recommendation of flash.utils.IExternalizable. A remote attacker with the ability to spoof or control an RMI server connection may be able to send serialized Java objects that execute arbitrary code when deserialized.
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Analysis
by VulDB Data Team • 12/26/2024
The vulnerability CVE-2017-3207 represents a critical deserialization flaw in the WebORB for Java implementation that affects version 5.1.1.0. This issue stems from a deviation in the AMF3 deserialization process where the software incorrectly derives class instances from java.io.Externalizable instead of adhering to the AMF3 specification's mandated flash.utils.IExternalizable interface. The root cause lies in the improper handling of serialized objects during the deserialization phase, creating a pathway for remote code execution through maliciously crafted serialized data. This deviation from the established specification creates a fundamental security gap that can be exploited by attackers with network access to the vulnerable system.
The technical flaw manifests when the AMF3 deserializer processes serialized objects that contain class definitions derived from java.io.Externalizable rather than flash.utils.IExternalizable. This misalignment allows attackers to manipulate the deserialization process by crafting serialized objects that leverage the java.io.Externalizable interface's capabilities to execute arbitrary code during the deserialization phase. The vulnerability specifically impacts systems that utilize RMI (Remote Method Invocation) connections, where an attacker with the ability to control or spoof an RMI server connection can inject malicious serialized objects that will be processed by the vulnerable WebORB implementation. The flaw operates at the core of Java's serialization mechanism, exploiting the trust placed in serialized objects and the lack of proper validation during deserialization.
The operational impact of this vulnerability is severe and far-reaching, as it enables remote code execution without requiring authentication or specific user interaction. An attacker who can establish a connection to an RMI server that processes AMF3 serialized data can potentially execute arbitrary code on the target system with the privileges of the running application. This creates a significant risk for enterprise applications that rely on WebORB for Java, particularly those handling sensitive data or serving as backend services for web applications. The vulnerability can be exploited across network boundaries, making it particularly dangerous in cloud environments or systems with exposed RMI endpoints. The attack surface is broad since any application using the vulnerable WebORB version that accepts AMF3 serialized data from untrusted sources becomes a potential target.
Mitigation strategies for CVE-2017-3207 should prioritize immediate patching of the WebORB for Java implementation to version 5.1.1.1 or later, which addresses the incorrect implementation of AMF3 deserialization. Organizations should implement network segmentation to restrict access to RMI endpoints and limit the exposure of vulnerable services to trusted networks only. Additional protective measures include disabling unnecessary RMI services, implementing strict input validation for all serialized data, and monitoring for suspicious deserialization activities. The implementation of Java security policies that restrict deserialization of untrusted objects can provide an additional layer of protection. From a defensive perspective, this vulnerability aligns with CWE-502 which categorizes deserialization of untrusted data as a critical security weakness, and it maps to ATT&CK technique T1059.007 for remote code execution through serialized objects. Organizations should also consider implementing application firewalls and intrusion detection systems to monitor for potential exploitation attempts targeting this specific vulnerability.