Post Exploitation - Malware & Escalation
Chapter: Post-Exploitation Techniques in Cybersecurity
Introduction
Post-exploitation refers to the activities performed after gaining unauthorized access to a system. This stage is critical as it allows an attacker to gather information, maintain persistence, escalate privileges, and ultimately achieve their objectives. This chapter will provide an in-depth look at post-exploitation techniques across different operating systems—Windows, Linux, and macOS—along with the various stages involved in the process.
1. Overview of Post-Exploitation
What is Post-Exploitation?
Post-exploitation involves actions taken after successfully exploiting a vulnerability to achieve specific goals. This phase focuses on:
Maintaining access to the compromised system.
Gathering information about the network and other systems.
Escalating privileges to gain higher-level access.
Exfiltrating data or carrying out further attacks.
Goals of Post-Exploitation
Data Exfiltration: Stealing sensitive data from the compromised system.
Establishing Persistence: Ensuring continued access even after the initial exploit is patched.
Lateral Movement: Exploring and exploiting other systems within the network.
2. Post-Exploitation Stages
The post-exploitation process can be divided into several stages:
Stage
Description
1. Assessment
Gather information about the system and network (user accounts, services, etc.).
2. Privilege Escalation
Attempt to gain higher-level permissions to access more resources.
3. Persistence
Establish methods to maintain access to the compromised system.
4. Lateral Movement
Move to other systems within the network to expand control.
5. Data Exfiltration
Collect and transmit sensitive data out of the target network.
6. Covering Tracks
Remove traces of the attack to evade detection.
3. Post-Exploitation Techniques by Operating System
3.1 Windows Post-Exploitation Techniques
Assessment Techniques
System Information: Use commands like
systeminfoto gather details about the OS, patches, and network configuration.User Enumeration: Tools like PowerView can enumerate user accounts and groups in Active Directory.
Privilege Escalation
Token Manipulation: Use tools like Mimikatz to extract credentials and tokens for privilege escalation.
Service Misconfigurations: Exploit improperly configured services that run with elevated privileges.
Persistence Techniques
Scheduled Tasks: Create new scheduled tasks to maintain access.
Windows Services: Create a new service or modify an existing one to run malware.
Lateral Movement
PsExec: Use PsExec to execute commands on other systems within the network.
WMI (Windows Management Instrumentation): Use WMI to execute commands remotely.
Data Exfiltration
PowerShell: Use PowerShell scripts to gather and send sensitive data to an external server.
Netcat: Utilize Netcat to transfer files or establish reverse shells.
Covering Tracks
Clear Logs: Use commands like
wevtutilto clear Windows event logs.Modify Registry: Alter registry settings to hide traces of exploitation.
3.2 Linux Post-Exploitation Techniques
Assessment Techniques
System Information: Use commands like
uname -aandcat /etc/os-releasefor system details.User Enumeration: Check
/etc/passwdfor user accounts and groups.
Privilege Escalation
SUID/SGID Files: Identify and exploit files with SUID/SGID permissions using commands like
find / -perm -4000.Kernel Exploits: Search for kernel vulnerabilities specific to the OS version using tools like Linux Exploit Suggester.
Persistence Techniques
Cron Jobs: Add entries to cron jobs to execute scripts at regular intervals.
Startup Scripts: Place scripts in
/etc/init.d/to run on boot.
Lateral Movement
SSH: Use SSH keys to access other machines on the network.
RDP (Remote Desktop Protocol): Use existing RDP connections to move laterally.
Data Exfiltration
Curl/Wget: Use Curl or Wget to download or upload sensitive data to external servers.
Netcat: Utilize Netcat for data transfer.
Covering Tracks
Clear Logs: Use
echo "" > /var/log/syslogto clear logs.Modify History: Clear command history using
history -c.
3.3 macOS Post-Exploitation Techniques
Assessment Techniques
System Information: Use
system_profilerto gather detailed system information.User Enumeration: Check
/etc/passwdfor user accounts and groups.
Privilege Escalation
Kernel Extensions: Exploit misconfigured kernel extensions for privilege escalation.
Application Vulnerabilities: Identify and exploit application vulnerabilities (e.g., outdated software).
Persistence Techniques
Launch Daemons: Create custom launch daemons to maintain access.
Cron Jobs: Use cron jobs to schedule tasks for execution.
Lateral Movement
SSH: Use SSH keys for remote access to other machines.
Apple Remote Desktop: Utilize ARD for remote access to other Macs.
Data Exfiltration
Curl/Wget: Use Curl or Wget to transfer files to external servers.
Netcat: Employ Netcat for file transfers.
Covering Tracks
Clear Logs: Use
sudo rm -rf /var/log/*to remove logs.Modify History: Clear terminal history using
history -c.
4. Tools for Post-Exploitation
Tool
Description
Use Case
Metasploit
Exploitation framework that includes post-exploitation modules.
Maintaining access and executing commands on compromised systems.
Empire
PowerShell and Python post-exploitation framework for Windows and Linux.
Establishing persistence and executing remote commands.
Cobalt Strike
Adversary simulation software that provides advanced post-exploitation features.
Lateral movement and data exfiltration.
Mimikatz
Tool for credential harvesting and privilege escalation on Windows.
Extracting plaintext passwords, Kerberos tickets, etc.
Netcat
Networking utility for reading and writing data across networks.
Establishing reverse shells and transferring files.
5. Hands-On Exercises
Exercise 1: Windows Post-Exploitation
Objective: Use Mimikatz to extract credentials from a compromised Windows machine.
Tools: Mimikatz, PowerShell.
Exercise 2: Linux Privilege Escalation
Objective: Identify and exploit a SUID binary to escalate privileges on a Linux system.
Tools: Linux Exploit Suggester, find command.
Exercise 3: macOS Persistence
Objective: Create a Launch Daemon to maintain access on a macOS system.
Tools: Terminal commands for creating plist files.
6. Real-Life Case Studies
1. SolarWinds Attack (2020)
Description: Attackers exploited vulnerabilities in SolarWinds software to gain access to numerous organizations.
Post-Exploitation Techniques: Gained persistence through software updates and used lateral movement within networks to escalate privileges.
2. Target Data Breach (2013)
Description: Attackers accessed Target’s systems through a third-party vendor.
Post-Exploitation Techniques: Used stolen credentials to move laterally within Target's network and exfiltrate data.
7. Best Practices for Post-Exploitation
Documentation: Keep detailed records of actions taken during post-exploitation for analysis and reporting.
Responsible Disclosure: If sensitive data is exposed, responsibly disclose vulnerabilities to affected parties.
Cover Tracks: Always ensure traces of exploitation are removed to avoid detection.
8. Conclusion
Post-exploitation is a crucial phase in the penetration testing process that enables security professionals to understand the full scope of vulnerabilities in an environment. By mastering techniques across different operating systems and employing various tools, ethical hackers can effectively assess security postures and provide actionable insights for improvement.
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