Post Exploitation - Malware & Escalation

Chapter: Post-Exploitation Techniques in Cybersecurity

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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.

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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.

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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.

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3. Post-Exploitation Techniques by Operating System

3.1 Windows Post-Exploitation Techniques

Assessment Techniques

• System Information: Use commands like systeminfo to 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 wevtutil to 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 -a and cat /etc/os-release for system details.

• User Enumeration: Check /etc/passwd for 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/syslog to clear logs.

• Modify History: Clear command history using history -c.

3.3 macOS Post-Exploitation Techniques

Assessment Techniques

• System Information: Use system_profiler to gather detailed system information.

• User Enumeration: Check /etc/passwd for 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.

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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.

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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.

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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.

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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.

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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.