ESB-2018.0483 - [Win][UNIX/Linux] Jenkins: Access privileged data - Existing account 2018-02-16

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             AUSCERT External Security Bulletin Redistribution

                         Jenkins Security Updates
                             16 February 2018


        AusCERT Security Bulletin Summary

Product:           Jenkins
Publisher:         Jenkins
Operating System:  UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Access Privileged Data         -- Existing Account
                   Provide Misleading Information -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-6356  

Original Bulletin:

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Jenkins Security Advisory 2018-02-14

This advisory announces vulnerabilities in the following Jenkins deliverables:

    Jenkins (core)


Improperly secured form validation for proxy configuration allowed Server-Side 
Request Forgery

SECURITY-506 / CVE pending

The form validation for the proxy configuration form did not check the permission 
of the user accessing it, allowing anyone with Overall/Read access to Jenkins to 
cause Jenkins to send a GET request to a specified URL, optionally with a specified 
proxy configuration.

If that request's HTTP response code indicates success, the form validation is 
returning a generic success message, otherwise the HTTP status code is returned. 
It was not possible to reuse an existing proxy configuration to send those 
requests; that configuration had to be provided by the attacker.

The form validation now properly requires the Overall/Administer permission.

Path traversal vulnerability allows access to files outside plugin resources

SECURITY-705 / CVE-2018-6356

Jenkins did not properly prevent specifying relative paths that escape a base 
directory for URLs accessing plugin resource files. This allowed users with 
Overall/Read permission to download files from the Jenkins master they should 
not have access to.

On Windows, any file accessible to the Jenkins master process could be downloaded. 
On other operating systems, any file within the Jenkins home directory accessible 
to the Jenkins master process could be downloaded.

Jenkins now prevents specifying paths containing .. and other character sequences 
that could be used to access files outside the plugins resource directory.

Improper input validation allows unintended access to plugin resource files on 
case-insensitive file systems

SECURITY-717 / CVE pending

Jenkins did not take into account case-insensitive file systems when preventing 
access to plugin resource files that should not be accessible. This allowed users 
with Overall/Read permission to download plugin resource files in META-INF and 
WEB-INF directories, such as the plugins' JAR files, which could contain 
hardcoded secrets.

This was caused by an incomplete fix to SECURITY-155.


    SECURITY-506: medium
    SECURITY-705: medium
    SECURITY-717: medium

Affected Versions

    Jenkins weekly up to and including 2.106
    Jenkins LTS up to and including 2.89.3


    Jenkins weekly should be updated to version 2.107
    Jenkins LTS should be updated to version 2.89.4

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


The Jenkins project would like to thank the reporters for discovering and 
reporting these vulnerabilities:

    Daniel Beck, CloudBees, Inc. for SECURITY-506, SECURITY-717
    Kapil Kulkarni for SECURITY-705

Other Resources

    Announcement blog post

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