Jenkins Stapler Web Framework Arbitrary Code Execution Vulnerability [CVE-2018-1000861]

CVE Number – CVE-2018-1000861

A vulnerability in the Stapler web framework of Jenkins could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system.

The vulnerability is due to improper handling of HTTP requests by the stapler/core/src/main/java/org/kohsuke/stapler/MetaClass.java code of the Stapler web framework used by the affected software. An attacker could exploit this vulnerability by persuading a user to access a link that submits malicious input to the targeted system. An exploit could allow the attacker to invoke certain methods that are not intended to be invoked, which the attacker could use to execute arbitrary code. 

Jenkins has confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, an attacker may persuade a user to access a link that submits malicious input to the targeted system by using misleading language and instructions.

Safeguards

• Administrators are advised to apply the appropriate updates.
  
  Administrators are advised to allow only trusted users to have network access.
  
  Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.
  
  Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
  
  Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
  
  Administrators are advised to monitor affected systems.

Vendor Announcements

• Jenkins has released a security advisory at the following link: Jenkins Security Advisory 2018-12-05 – SECURITY-595

Fixed Software

• Jenkins has released a security advisory at the following link: Jenkins 2.154, 2.138.4, and 2.150.