crumbIssuer

enables proxy compatibility on startup

-Djenkins.model.Jenkins.crumbIssuerProxyCompatibility=true

temporary settings in Script:

System.setProperty('jenkins.model.Jenkins.crumbIssuerProxyCompatibility', 'true')
System.getProperty('jenkins.model.Jenkins.crumbIssuerProxyCompatibility')

change in Configure Global Security

Improved CSRF protection

Upgrading to Jenkins 2.176.2
SECURITY-626
CSRF
/
tokens (crumbs) are now only valid for the web session they were created in to limit the impact of attackers obtaining them. Scripts that obtain a crumb using the `/crumbIssuer/api` URL will now fail to perform actions protected from CSRF unless the scripts retain the web session ID in subsequent requests. - [CSRF Protection Explained](https://support.cloudbees.com/hc/en-us/articles/219257077-CSRF-Protection-Explained)

Scripts could instead use an API token, which has not required a CSRF token (crumb) since Jenkins 2.96.

working with session after `2.176.2` since SECURITY-626

references:
via curl
via wget

via curl

[!TIP] check cookie

$ cat ${COOKIEJAR}
# Netscape HTTP Cookie File
# https://curl.se/docs/http-cookies.html
# This file was generated by libcurl! Edit at your own risk.
#HttpOnly_jenkins.marslo.com.com  FALSE / TRUE  0 JSESSIONID.a054fd7a node015xsx4fybmo2k1oxpjg5f2dzw4265.node0

SERVER="http://localhost:8080"
# File where web session cookie is saved
COOKIEJAR="$(mktemp)"

CRUMB=$(curl -u "admin:admin" \
             --cookie-jar "$COOKIEJAR" \
             "$SERVER/crumbIssuer/api/xml?xpath=concat(//crumbRequestField,%22:%22,//crumb)" \
       )
curl -X POST \
     -u "admin:admin" \
     --cookie "$COOKIEJAR" \
     -H "$CRUMB" \
     "$SERVER"/job/someJob/build

via wget

SERVER="http://localhost:8080"
# File where web session cookie is saved
COOKIEJAR="$(mktemp)"

CRUMB="$(wget --user=admin \
              --password=admin \
              --auth-no-challenge \
              --save-cookies "$COOKIEJAR" \
              --keep-session-cookies \
              -q \
              --output-document \
              - \
              "$SERVER/crumbIssuer/api/xml?xpath=concat(//crumbRequestField,%22:%22,//crumb)"
        )"
wget --user=admin \
     --password=admin \
     --auth-no-challenge \
     --load-cookies "$COOKIEJAR" \
     --header="$CRUMB" \
     --post-data="" \
     -q \
     "$SERVER"/job/someJob/build

example

with crumb only

will get issue 403: No valid crumb was included in the request

$ curl -H ${crumb} \
       -X POST \
       https://jenkins.marslo.com/safeRestart
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<title>Error 403 No valid crumb was included in the request</title>
</head>
<body><h2>HTTP ERROR 403 No valid crumb was included in the request</h2>
<table>
<tr><th>URI:</th><td>/safeRestart</td></tr>
<tr><th>STATUS:</th><td>403</td></tr>
<tr><th>MESSAGE:</th><td>No valid crumb was included in the request</td></tr>
<tr><th>SERVLET:</th><td>Stapler</td></tr>
</table>
<hr><a href="https://eclipse.org/jetty">Powered by Jetty:// 9.4.39.v20210325</a><hr/>

</body>
</html>

with crumb and cookie

$ COOKIEJAR="$(mktemp)"
$ CRUMB="$(curl -s \
              --cookie-jar "${COOKIEJAR}" \
              "https://jenkins.marslo.com/crumbIssuer/api/json" |
              jq -r '.crumbRequestField + ":" + .crumb'
         )"
$ curl -v \
       -X POST \
       --cookie "${COOKIEJAR}" \
       -H "${CRUMB}" \
       https://jenkins.marslo.com/safeRestart
...
* Connection state changed (MAX_CONCURRENT_STREAMS == 250)!
< HTTP/2 302
< date: Wed, 09 Jun 2021 15:25:14 GMT
< location: https://jenkins.marslo.com/
< server: Jetty(9.4.39.v20210325)
< vary: Accept-Encoding
< x-content-type-options: nosniff
< content-length: 0
<
* Connection #0 to host jenkins.marslo.com left intact

To disable this improvement you can set the system property

via JAVA_OPTS

-Dhudson.security.csrf.DefaultCrumbIssuer.EXCLUDE_SESSION_ID=true

temporary settings in Script:

example for SECURITY-626

System.setProperty('hudson.security.csrf.DefaultCrumbIssuer.EXCLUDE_SESSION_ID', 'true')
System.getProperty('hudson.security.csrf.DefaultCrumbIssuer.EXCLUDE_SESSION_ID')

via plugin Strict Crumb Issuer

get crumberIssuer with script

import org.jenkinsci.plugins.strictcrumbissuer.StrictCrumbIssuer

StrictCrumbIssuer issuer = jenkins.model.Jenkins.instance.crumbIssuer
String jenkinsCrumb = "${issuer.crumbRequestField}:${issuer.crumb}"
println jenkinsCrumb

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enables proxy compatibility on startup

Improved CSRF protection

working with session after 2.176.2 since SECURITY-626

working with session after `2.176.2` since SECURITY-626