CloudBees Security Advisory 2017-04-26

This advisory announces multiple vulnerabilities in Jenkins, CloudBees Jenkins Platform, and CloudBees Jenkins Solutions.

CSRF: Multiple vulnerabilities

SECURITY-412 through SECURITY-420 / CVE-2017-1000356

Multiple Cross-Site Request Forgery vulnerabilities in Jenkins allowed malicious users to perform several administrative actions by tricking a victim into opening a web page. The most notable ones:

  • SECURITY-412: Restart Jenkins immediately, after all builds are finished, or after all plugin installations and builds are finished
  • SECURITY-412: Schedule a downgrade of Jenkins to a previously installed version if Jenkins previously upgraded itself
  • SECURITY-413: Install and (optionally) dynamically load any plugin present on a configured update site
  • SECURITY-414: Remove any update site from the Jenkins configuration
  • SECURITY-415: Change a user’s API token
  • SECURITY-416: Submit system configuration
  • SECURITY-417: Submit global security configuration
  • SECURITY-418, SECURITY-420: For Jenkins user database authentication realm: create an account if signup is enabled; or create an account if the victim is an administrator, possibly deleting the existing default ‘admin’ user in the process
  • SECURITY-419: Create a new agent, possibly executing arbitrary shell commands on the master node by choosing the appropriate launch method
  • SECURITY-420: Cancel a scheduled restart
  • SECURITY-420: Configure the global logging levels
  • SECURITY-420: Create a copy of an existing agent
  • SECURITY-420: Create copies of views in users’ “My Views” or as children of the experimental “Tree View” feature
  • SECURITY-420: Enter “quiet down” mode in which no new builds are started
  • SECURITY-420: On Windows, after successful installation as a service, restart
  • SECURITY-420: On Windows, try to install Jenkins as a service
  • SECURITY-420: Set the descriptions of items (jobs), builds, and users
  • SECURITY-420: Submit global tools configuration (Jenkins 2.0 and up)
  • SECURITY-420: Toggle keeping a build forever (i.e. exclude or include it in log rotation)
  • SECURITY-420: Try to connect all disconnected agents simultaneously
  • SECURITY-420: Update the node monitor data on all agents

The above, as well as several other more minor issues, have all been fixed and these actions now require POST requests, and, if configured, a CSRF crumb, to work.

CLI: Unauthenticated remote code execution

SECURITY-429 / CVE-2017-1000353

An unauthenticated remote code execution vulnerability allowed attackers to transfer a serialized Java SignedObject object to the remoting-based Jenkins CLI, that would be deserialized using a new ObjectInputStream, bypassing the existing blacklist-based protection mechanism.

SignedObject has been added to the remoting blacklist.

Additionally, the remoting-based CLI protocol has been deprecated and a new, HTTP based protocol introduced as the new default, in addition to the existing SSH-based CLI. This feature is available from CloudBees Jenkins Team 2.46.2.2, CloudBees Jenkins Platform  2.46.2.2 (Rolling Train), and CloudBees Jenkins Enterprise 1.6.3. It is strongly recommended that users upgrading to any of these versions disable the remoting-based CLI, and use one of the other modes (HTTP or SSH) instead.

CLI: Login command allowed impersonating any Jenkins user

SECURITY-466 / CVE-2017-1000354

The login command available in the remoting-based CLI stored the encrypted user name of the successfully authenticated user in a cache file used to authenticate further commands. Users with sufficient permission to create secrets in Jenkins, and download their encrypted values (e.g. with Job/Configure permission), were able to impersonate any other Jenkins user on the same instance.

This has been fixed by storing the cached authentication as a hash-based MAC with a key specific to the Jenkins instance and the CLI authentication cache.

Previously cached authentications are invalidated when upgrading Jenkins to a version containing a fix for this.

XStream: Java crash when trying to instantiate void/Void

SECURITY-503 / CVE-2017-1000355

Jenkins uses the XStream library to serialize and deserialize XML. Its maintainer recently published a security vulnerability that allows anyone able to provide XML to Jenkins for processing using XStream to crash the Java process. In Jenkins this typically applies to users with permission to create or configure items (jobs), views, or agents.

Jenkins now prohibits the attempted deserialization of void / Void that results in a crash.

Severity: 
  • ​​​​​​SECURITY-412 through SECURITY-420: high
  • SECURITY-429: critical
  • SECURITY-466: high
  • SECURITY-503: medium
Fix: 
  • CloudBees Jenkins Enterprise should be upgraded to 1.6.3 (available on April 27th).
  • CloudBees Jenkins Platform:
    • CloudBees Jenkins Operations Center 2.x.y.z (Rolling Train) should be upgraded to 2.46.2.1.
    • CloudBees Jenkins Operations Center 2.7.x.0.y (Fixed Train) should be upgraded to 2.7.24.0.1.
    • CloudBees Jenkins Operations Center 1.625.x.y should be upgraded to 1.625.24.1.
    • CloudBees Jenkins Enterprise 2.x.y.z (Rolling Train) should be upgraded to 2.46.2.1.
    • CloudBees Jenkins Enterprise 2.7.x.0.y (Fixed Train) should be upgraded to 2.7.24.0.1.
    • CloudBees Jenkins Enterprise 1.651.x.y should be upgraded to 1.651.24.1.
  • CloudBees Jenkins Team should be upgraded to 2.46.2.1.
  • Jenkins LTS should be upgraded to 2.46.2.
  • Jenkins main line should be upgraded to Jenkins 2.57.
  • DEV@cloud is already protected.

These versions include fixes to all the vulnerabilities described above. All prior versions are affected by these vulnerabilities unless otherwise indicated.