Full Report
NCC Group performed a pentest in which they had (notionally) compromised a developer's laptop who could commit code to a certain Java library. The researchers set a pre-requirement file to one that provided a Meterpreter shell from within the target build environment. They fou...
Analysis Summary
# Tool/Technique: Meterpreter Shell (via Pre-requirement File)
## Overview
A payload used to gain a remote, interactive command-and-control session (a reverse shell) on a compromised target system, delivered here via a specially crafted pre-requirement file within a development/build environment context.
## Technical Details
- Type: Tool / Payload (Associated with Metasploit Framework)
- Platform: Generic (Implied Windows/Linux environment based on Meterpreter's capabilities, running within a build environment/pod)
- Capabilities: Establishing a persistent, interactive command shell, executing arbitrary commands, escalating privileges, and data exfiltration on the compromised host.
- First Seen: N/A (Meterpreter has been active for many years)
## MITRE ATT&CK Mapping
- [TA0001 - Initial Access]
- [T1190 - Exploit Public-Facing Application] (Indirectly, through a complex chain involving a compromised developer workflow)
- [TA0011 - Command and Control]
- [T1071 - Application Layer Protocol] (If Meterpreter uses standard protocols for C2)
- [TA0003 - Persistence] (Meterpreter often attempts to establish persistence)
## Functionality
### Core Capabilities
- Establishing a reverse shell connection back to the attacker's listening station.
- Interactive remote access to the compromised build environment pod.
### Advanced Features
- The shell was specifically delivered by placing a malicious pre-requirement file into the build process, leveraging the trust within the CI/CD pipeline to execute the payload upon build initiation.
## Indicators of Compromise
- File Hashes: N/A (The specific hash of the payload file is not mentioned)
- File Names: Pre-requirement file (Name relies on the library's specific build system, e.g., potentially a dependency file for a Java project)
- Registry Keys: N/A
- Network Indicators: C2 connection established by the Meterpreter payload to the attacker-controlled listener (IP/Port not specified, must be defanged: `attacker_c2_ip:port`).
- Behavioral Indicators: Unexpected outbound connections originating from the build server/pod, especially if they use protocols often abused by Meterpreter (e.g., HTTPS, DNS).
## Associated Threat Actors
- Various threat actors, penetration testers, and red teams, as Meterpreter is the default payload for the Metasploit Framework.
## Detection Methods
- Signature-based detection: Signatures for known Meterpreter staged payloads or DLLs.
- Behavioral detection: Monitoring processes that execute payloads within build environments or detecting unexpected outbound network connections initiated by build processes (like `git`, `javac`, or related tools).
- YARA rules: Rules targeting known Meterpreter artifacts.
## Mitigation Strategies
- **Least Privilege:** Ensure build environments (like Jenkins agents/pods) have minimal permissions and cannot execute arbitrary code outside their defined scope.
- **Input Validation:** Thoroughly vet all code commits, dependencies, and configuration files, especially those that influence the build process (like pre-requirement files).
- **Network Segmentation:** Network restrictions preventing build environments from initiating arbitrary outbound connections to the internet or other internal environments.
## Related Tools/Techniques
- Metasploit Framework
- Reverse Shell (General technique)
- SSH Key usage (Observed subsequently: Using keys found to access the Jenkins master)