CVE-2017-5929 in Logback
Summary
by MITRE
QOS.ch Logback before 1.2.0 has a serialization vulnerability affecting the SocketServer and ServerSocketReceiver components.
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Analysis
by VulDB Data Team • 09/06/2020
The vulnerability identified as CVE-2017-5929 represents a critical serialization flaw within the QOS.ch Logback logging framework prior to version 1.2.0. This issue specifically impacts the SocketServer and ServerSocketReceiver components, which are designed to receive and process log messages over network connections. The vulnerability stems from insufficient validation of serialized objects when these components deserialize data received from remote sources, creating an avenue for remote code execution attacks. The affected components operate by accepting serialized Java objects through socket connections, making them susceptible to malicious payload injection during the deserialization process. This flaw directly violates fundamental security principles of input validation and object deserialization safety, as demonstrated by the CWE-502 weakness classification which addresses "Deserialization of Untrusted Data" in the Common Weakness Enumeration catalog.
The technical exploitation of this vulnerability occurs when an attacker sends a maliciously crafted serialized object to a Logback SocketServer or ServerSocketReceiver instance. The deserialization process lacks proper validation mechanisms to verify the integrity and authenticity of the incoming serialized data, allowing attackers to inject arbitrary Java objects that can execute code on the target system. The attack vector leverages the inherent dangers of Java deserialization where untrusted input can trigger arbitrary code execution through gadgets within the Java runtime environment. This vulnerability aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1203 for "Exploitation for Client Execution" when attackers leverage the deserialization flaw to gain unauthorized access to systems running vulnerable Logback implementations. The impact extends beyond simple code execution to potentially allow full system compromise, data exfiltration, and lateral movement within network environments where these logging components are deployed.
Organizations utilizing Logback versions prior to 1.2.0 face significant operational risks when their systems process untrusted network input through SocketServer or ServerSocketReceiver components. The vulnerability can be exploited remotely without authentication, making it particularly dangerous in environments where logging servers are exposed to untrusted networks or where network segmentation is inadequate. Attackers can leverage this vulnerability to establish persistent backdoors, escalate privileges, or use the compromised systems as launch points for further attacks. The widespread adoption of Logback in enterprise applications and web services means that a successful exploitation could affect numerous organizations simultaneously. The vulnerability's impact is amplified by the fact that many applications rely on these logging components for network-based log aggregation, making the attack surface larger than initially apparent. Organizations should consider implementing network segmentation, firewall rules, and monitoring for unusual socket activity as defensive measures against potential exploitation attempts.
The primary mitigation strategy involves upgrading to Logback version 1.2.0 or later, which includes proper deserialization safeguards and input validation for the affected components. Additionally, organizations should disable or remove the SocketServer and ServerSocketReceiver components from their configurations if they are not actively required, as these components represent the attack surface for this vulnerability. Network-level mitigations include implementing strict firewall rules to restrict access to logging ports and monitoring for anomalous deserialization patterns. Security teams should also consider implementing application whitelisting policies and using tools that can detect and prevent the execution of malicious serialized objects. The remediation process requires careful testing to ensure that the upgrade does not disrupt existing logging functionality, while also validating that the network configurations properly isolate the logging components from untrusted sources. Organizations should conduct vulnerability assessments to identify all systems running vulnerable Logback versions and prioritize remediation efforts based on risk exposure and business criticality.