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AUSCERT External Security Bulletin Redistribution
ESB-2018.2414
Jenkins Security Advisory 2018-08-15
17 August 2018
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AusCERT Security Bulletin Summary
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Product: Jenkins core
Publisher: Jenkins
Operating System: Windows
UNIX variants (UNIX, Linux, OSX)
Impact/Access: Denial of Service -- Remote with User Interaction
Unauthorised Access -- Remote/Unauthenticated
Access Confidential Data -- Remote with User Interaction
Resolution: Patch/Upgrade
Original Bulletin:
https://jenkins.io/security/advisory/2018-08-15/
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Jenkins Security Advisory 2018-08-15
This advisory announces vulnerabilities in the following Jenkins deliverables:
o Jenkins (core)
Descriptions
Jenkins allowed deserialization of URL objects with host components
SECURITY-637 / CVE pending
Jenkins allowed deserialization of URL objects via Remoting (agent
communication) and XStream.
This could in rare cases be used by attackers to have Jenkins look up
specified hosts' DNS records.
Jenkins now injects a URLStreamHandler when deserializing URLs that overrides
the affected URL methods.
This can be disabled if needed by setting the system property
hudson.remoting.URLDeserializationHelper.avoidUrlWrapping to true.
Ephemeral user record was created on some invalid authentication attempts
SECURITY-672 / CVE pending
When attempting to authenticate using API token, an ephemeral user record was
created to validate the token in case an external security realm was used, and
the user record in Jenkins not previously saved, as (legacy) API tokens could
exist without a persisted user record.
This behavior could be abused to create a large number of ephemeral user
records in memory.
The API token validation on authentication has been improved to no longer
create ephemeral user records.
Cron expression form validation could enter infinite loop, potentially
resulting in denial of service
SECURITY-790 / CVE pending
The form validation for cron expressions (e.g. "Poll SCM", "Build
periodically") could enter infinite loops when cron expressions only matching
certain rare dates were entered, blocking request handling threads
indefinitely.
"Remember me" cookie was evaluated even if that feature is disabled
SECURITY-996 / CVE pending
The "Remember me" feature can be disabled in the Jenkins security
configuration.
This did not disable the processing of previously set "Remember me" cookies,
so they still allowed users to be logged in.
"Remember me" cookies are no longer evaluated when the corresponding feature
is disabled.
Unauthorized users could access agent logs
SECURITY-1071 / CVE pending
Users with Overall/Read permission were able to access the URL serving agent
logs on the UI due to a lack of permission checks.
Access to the affected URL is now limited to users with the correct Agent/
Connect permission.
Unauthorized users could cancel scheduled restarts initiated from the update
center
SECURITY-1076 / CVE pending
Users with Overall/Read permission were able to access the URL used to cancel
scheduled restart jobs initiated via the update center ("Restart Jenkins when
installation is complete and no jobs are running") due to a lack of permission
checks.
Access to the affected URL is now limited to users with Overall/Administer
permission.
Severity
o SECURITY-637: low
o SECURITY-672: medium
o SECURITY-790: medium
o SECURITY-996: low
o SECURITY-1071: medium
o SECURITY-1076: low
Affected Versions
o Jenkins weekly up to and including 2.137
o Jenkins LTS up to and including 2.121.2
Fix
o Jenkins weekly should be updated to version 2.138
o Jenkins LTS should be updated to version 2.121.3
These versions include fixes to the vulnerabilities described above. All prior
versions are considered to be affected by these vulnerabilities unless
otherwise indicated.
Credit
The Jenkins project would like to thank the reporters for discovering and
reporting these vulnerabilities:
o Jesse Glick, CloudBees, Inc. for SECURITY-637
o Thomas de Grenier de Latour for SECURITY-790
o Wadeck Follonier, CloudBees, Inc. for SECURITY-1071, SECURITY-1076
o Wadeck Follonier, CloudBees, Inc., and, independently, Nimrod Stoler of
CyberArk Labs for SECURITY-672
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