GCP - Post Exploitation
Introduction
After successfully exploiting a target on the Google Cloud Platform (GCP), it is important to understand the post-exploitation techniques that can be used to further compromise the system and maintain access. This section will cover various post-exploitation techniques specific to GCP.
Table of Contents
Persistence
Once access has been gained to a GCP instance, it is crucial to establish persistence to maintain access even after a system reboot. This can be achieved by creating a backdoor, modifying startup scripts, or leveraging scheduled tasks.
Backdoors
Creating a backdoor is a common method to maintain access to a compromised system. This can be done by adding a new user, modifying SSH configurations, or installing a remote access tool.
Startup Scripts
GCP allows users to define startup scripts that are executed when an instance boots up. By modifying these scripts, an attacker can execute arbitrary commands or install additional software.
Scheduled Tasks
Leveraging scheduled tasks can also provide persistence. By creating a task that runs at regular intervals, an attacker can ensure continued access to the compromised system.
Privilege Escalation
Privilege escalation is the process of gaining higher levels of access on a system. In GCP, there are several techniques that can be used to escalate privileges.
Misconfigured IAM Roles
If the target instance has misconfigured Identity and Access Management (IAM) roles, an attacker can abuse this misconfiguration to gain higher privileges.
Exploiting Vulnerabilities
Exploiting vulnerabilities in GCP services or applications running on the target instance can also lead to privilege escalation.
Exploiting Misconfigurations
Misconfigurations in GCP services or applications can provide opportunities for privilege escalation. This includes misconfigured firewall rules, insecure storage buckets, or weak access controls.
Lateral Movement
Lateral movement involves moving from one compromised system to another within the same network. In GCP, lateral movement can be achieved through various techniques.
SSH Tunnels
SSH tunnels can be used to pivot from one compromised system to another. By forwarding ports through SSH, an attacker can access services running on other systems within the network.
VPN Tunnels
If the target network has a VPN connection to another network, an attacker can exploit this connection to gain access to systems on the other network.
Exploiting Trust Relationships
If there are trust relationships established between different GCP projects or services, an attacker can exploit these relationships to move laterally within the network.
Data Exfiltration
Data exfiltration involves stealing sensitive data from a compromised system. In GCP, there are several techniques that can be used to exfiltrate data.
Copying to External Storage
An attacker can copy sensitive data to an external storage bucket or another GCP project to exfiltrate it from the compromised system.
Using APIs
GCP provides various APIs that can be leveraged to exfiltrate data. This includes the Cloud Storage API, BigQuery API, or Datastore API.
DNS Tunneling
DNS tunneling can be used to exfiltrate data by encoding it within DNS queries and responses. This can bypass network security measures and allow for stealthy data exfiltration.
Covering Tracks
Covering tracks involves removing evidence of the attack to avoid detection. In GCP, there are several techniques that can be used to cover tracks.
Deleting Logs
An attacker can delete logs from GCP services to remove evidence of their activities. This includes logs from Cloud Logging, Cloud Audit Logs, or VPC Flow Logs.
Modifying Audit Trails
Modifying audit trails can help an attacker cover their tracks. This includes modifying logs, timestamps, or other audit information.
Hiding Backdoors
To avoid detection, an attacker can hide backdoors by modifying file permissions, disguising them as legitimate files, or encrypting them.
Conclusion
Understanding post-exploitation techniques specific to GCP is crucial for maintaining access and avoiding detection. By leveraging persistence, privilege escalation, lateral movement, data exfiltration, and covering tracks, an attacker can maximize their control over a compromised system.
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