Adversaries may inject malicious code into processes via the /proc filesystem in order to evade process-based defenses as well as possibly elevate privileges. Proc memory injection is a method of executing arbitrary code in the address space of a separate live process.
Proc memory injection involves enumerating the memory of a process via the /proc filesystem (/proc/[pid]) then crafting a return-oriented programming (ROP) payload with available gadgets/instructions. Each running process has its own directory, which includes memory mappings. Proc memory injection is commonly performed by overwriting the target processes’ stack using memory mappings provided by the /proc filesystem. This information can be used to enumerate offsets (including the stack) and gadgets (or instructions within the program that can be used to build a malicious payload) otherwise hidden by process memory protections such as address space layout randomization (ASLR). Once enumerated, the target processes’ memory map within /proc/[pid]/maps can be overwritten using dd.[1][2][3]
Other techniques such as Dynamic Linker Hijacking may be used to populate a target process with more available gadgets. Similar to Process Hollowing, proc memory injection may target child processes (such as a backgrounded copy of sleep).[2]
Running code in the context of another process may allow access to the process's memory, system/network resources, and possibly elevated privileges. Execution via proc memory injection may also evade detection from security products since the execution is masked under a legitimate process.
| ID | Mitigation | Description |
|---|---|---|
| M1040 | Behavior Prevention on Endpoint |
Some endpoint security solutions can be configured to block some types of process injection based on common sequences of behavior that occur during the injection process. |
| M1022 | Restrict File and Directory Permissions |
Restrict the permissions on sensitive files such as |
| ID | Data Source | Data Component |
|---|---|---|
| DS0022 | File | File Modification |
File system monitoring can determine if /proc files are being modified. Users should not have permission to modify these in most cases.
Analyze process behavior to determine if a process is performing actions it usually does not, such as opening network connections, reading files, or other suspicious actions that could relate to post-compromise behavior.