Proc Memory

Proc Memory [T1055.009]

Information

• Name: Proc Memory

• ID: T1055.009

• Tactics: TA0005, TA0004

• Technique: T1055

Introduction

Proc Memory (T1055.009) is a sub-technique within the MITRE ATT&CK framework under the Process Injection (T1055) category. It involves adversaries injecting malicious code directly into the memory space of running processes without writing to disk. By exploiting legitimate processes, attackers can conceal malicious activities, evade detection, and maintain persistence on compromised systems. This method is widely used due to its stealthiness, effectiveness, and the difficulty defenders face in detecting or attributing the malicious activity.

Deep Dive Into Technique

Proc Memory injection leverages direct manipulation of a running process's memory space to execute malicious code. Instead of creating new processes or writing malware files to disk, attackers inject code into existing processes, making detection significantly harder. The following steps outline the typical execution flow:

1. Process Identification: Attackers first identify suitable target processes that have high privileges, network access, or legitimate system behaviors to blend malicious activity seamlessly.

2. Memory Allocation: Attackers allocate memory within the target process's address space using API calls such as VirtualAllocEx (Windows) or similar functions on other operating systems.

3. Code Injection: Malicious payloads are directly written into the allocated memory space, typically using functions like WriteProcessMemory (Windows API) or equivalent system calls.

4. Execution of Injected Code: Attackers execute the injected payload by creating remote threads (CreateRemoteThread), modifying existing threads (QueueUserAPC), or hijacking existing threads through thread context manipulation (SetThreadContext).

Common mechanisms and techniques used for Proc Memory injection include:

• Reflective DLL Injection: Loading and executing a DLL entirely from memory without touching disk.

• Process Hollowing: Starting a legitimate process in a suspended state, hollowing out its memory, and injecting malicious code before resuming execution.

• Thread Hijacking: Manipulating existing threads within a process to execute injected code, minimizing suspicious thread creation events.

• Memory Patching: Modifying existing executable code in memory to redirect execution flow to malicious payloads.

When this Technique is Usually Used

Proc Memory injection is frequently employed across various attack scenarios and phases, including:

• Initial Access and Execution:

  • Attackers use memory injection immediately after exploiting vulnerabilities to gain initial footholds without leaving disk-based artifacts.

• Privilege Escalation and Credential Theft:

  • Injecting code into privileged processes helps attackers escalate privileges or extract sensitive credentials from memory without triggering alarms.

• Persistence and Defense Evasion:

  • By injecting malicious code into trusted processes, attackers maintain persistence and evade endpoint detection tools that monitor file-based malware.

• Command and Control (C2) Communication:

  • Injected payloads within trusted network processes facilitate stealthy communication with remote C2 servers, making malicious traffic appear legitimate.

• Lateral Movement:

  • Attackers utilize memory injection techniques to move laterally within compromised networks, injecting payloads into processes of remote systems via administrative tools or remote procedure calls.

How this Technique is Usually Detected

Detection of Proc Memory injection can be challenging due to its stealthy nature. However, multiple detection methods, tools, and indicators of compromise (IoCs) can help defenders identify this technique:

• Behavioral Analysis:

  • Monitoring abnormal process behaviors such as unexpected remote thread creation, unusual memory allocations, or thread context modifications.

• Endpoint Detection and Response (EDR) Tools:

  • Utilizing advanced EDR solutions capable of monitoring API calls (VirtualAllocEx, WriteProcessMemory, CreateRemoteThread) and suspicious process behaviors.

• Memory Forensics:

  • Performing memory dumps and analyzing them using tools like Volatility or Rekall to detect injected code, anomalous memory regions, or reflective DLLs.

• API Hooking and Monitoring:

  • Implementing API hooking techniques to detect suspicious API calls or patterns indicative of injection attempts.

• Sysmon and Windows Event Logs:

  • Leveraging Sysmon events (Event IDs 8, 10) and Windows audit logs to detect suspicious thread creation or process access events.

Indicators of Compromise (IoCs) specific to this technique include:

• Unusual memory allocations within sensitive or privileged processes.

• API calls such as VirtualAllocEx, WriteProcessMemory, CreateRemoteThread, and SetThreadContext executed from unexpected processes.

• Suspicious process behaviors, including sudden increases in memory usage or unexpected network connections.

• Presence of reflective DLLs or memory-resident payloads identifiable through memory analysis tools.

Why it is Important to Detect This Technique

Early detection of Proc Memory injection is crucial due to its severe potential impacts on systems and networks. Some of the key reasons include:

• Stealth and Evasion:

  • Injected malicious code bypasses traditional antivirus and file-based detection methods, making early detection critical to prevent prolonged compromise.

• Privilege Escalation and Credential Theft:

  • Attackers commonly leverage injected code within privileged processes to escalate privileges, steal credentials, and compromise critical assets.

• Persistence and Long-term Compromise:

  • Injected code can persist across system restarts or evade detection for extended periods, allowing attackers prolonged access and control.

• Lateral Movement and Network-wide Compromise:

  • Attackers use memory injection methods to propagate across the network, increasing the scope and severity of the compromise.

• Data Exfiltration and Damage:

  • Undetected injections enable attackers to exfiltrate sensitive data, disrupt operations, or deploy ransomware payloads, causing significant financial and reputational damage.

Examples

Real-world examples showcasing the use of Proc Memory injection techniques include:

• Cobalt Strike Framework:

  • Widely used penetration testing and adversary simulation tool capable of reflective DLL injection, process hollowing, and memory-resident payload execution. Attackers frequently abuse this tool to inject payloads directly into memory, evading traditional detection mechanisms.

• TrickBot Malware:

  • TrickBot employs reflective DLL injection and memory injection techniques to execute payloads within legitimate processes, stealing credentials, and facilitating lateral movement.

• Emotet Banking Trojan:

  • Emotet uses process injection techniques extensively, injecting malicious payloads into trusted processes such as explorer.exe or svchost.exe to evade detection and perform credential harvesting.

• Dridex Banking Trojan:

  • Dridex utilizes memory injection techniques to inject payloads directly into running processes, enabling credential theft, persistence, and stealthy command-and-control communication.

• FIN7 Cybercrime Group:

  • Known to leverage Proc Memory injection in their attacks, FIN7 injects malicious payloads into legitimate processes to evade detection, steal payment card data, and maintain long-term persistence on compromised systems.

These examples highlight the real-world prevalence, versatility, and severity of Proc Memory injection techniques used by threat actors to conduct sophisticated cyber operations.