Jenkins is an open-source automation server commonly used for continuous integration and continuous delivery (CI/CD). It allows users to automate tasks such as building, testing, and deploying software. Jenkins is widely used in DevOps environments and by developers for project automation. The server supports a wide range of plugins that extend its capabilities for integrating with other tools and systems. Jenkins can be deployed on various platforms, including Linux, Windows, and macOS. It is primarily used by software development teams to streamline development pipelines.
The CVE-2017-1000353 vulnerability affects Jenkins versions 2.56 and earlier, as well as LTS versions up to 2.46.1. It allows unauthenticated remote code execution via a deserialization flaw in the Jenkins CLI. Attackers can exploit this vulnerability by sending specially crafted serialized Java objects, bypassing security mechanisms, and executing arbitrary code. This flaw is a result of improper handling of serialized objects, allowing malicious payloads to be executed on the Jenkins server. The vulnerability can lead to complete system compromise if successfully exploited. Jenkins has taken steps to address the issue by adding protections and deprecating the vulnerable protocol.
The vulnerability is caused by Jenkins' use of Java serialization for its command-line interface (CLI). The system deserializes objects from untrusted sources, which allows an attacker to send a crafted `SignedObject` to the server. This bypasses the existing blacklist protections and can trigger remote code execution. The malicious object is deserialized using `ObjectInputStream`, and once executed, the attacker gains control of the Jenkins server. The vulnerability affects both Jenkins core and certain LTS versions, making it critical for organizations using those versions. Fixes were provided in newer versions of Jenkins, where the deserialization mechanism was tightened, and new protocols were introduced to mitigate the risk.
If exploited, this vulnerability can allow an attacker to execute arbitrary code remotely on a Jenkins server. This could lead to a complete compromise of the system, including unauthorized access to sensitive data, manipulation of build processes, or disruption of ongoing development workflows. In some cases, the attacker could escalate privileges to gain control over the underlying infrastructure. Exploiting the vulnerability without proper security measures in place could result in severe damage to the organization’s CI/CD pipeline and lead to a loss of data or intellectual property. Additionally, this could have broader implications for the security of the entire development environment.
REFERENCES
- Upgrade Jenkins to the latest stable version (2.54 or newer) to avoid this vulnerability.
- Disable the remoting-based CLI protocol by default and switch to the new HTTP-based CLI protocol.
- Ensure all deserialization processes in Jenkins are properly secured and consider blacklisting additional unsafe classes.
- Apply available security patches provided by Jenkins for affected versions.
- Restrict access to Jenkins CLI to trusted users and secure the Jenkins instance with appropriate firewalls and authentication measures.
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