Detect Proc Memory in Splunk
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 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 otherwise hidden by ASLR. Once enumerated, the target processes' memory map within /proc/[pid]/maps can be overwritten using dd.
MITRE ATT&CK
- Technique
- T1055 Process Injection
- Sub-technique
- T1055.009 Proc Memory
- Canonical reference
- https://attack.mitre.org/techniques/T1055/009/
SPL Detection Query
index=linux sourcetype="linux:audit" (type=SYSCALL OR type=PATH)
| eval is_proc_mem=if(match(name, "/proc/[0-9]+/mem$") OR match(path, "/proc/[0-9]+/mem$"), 1, 0)
| eval is_proc_maps=if(match(name, "/proc/[0-9]+/maps$") OR match(path, "/proc/[0-9]+/maps$"), 1, 0)
| where is_proc_mem=1 OR is_proc_maps=1
| eval exe_name=mvindex(split(exe, "/"), -1)
| search NOT exe_name IN ("ps", "top", "htop", "gdb", "strace", "ltrace", "perf", "systemd", "dockerd", "containerd")
| eval target_pid=replace(coalesce(name, path), "/proc/(\d+)/.*", "\1")
| eval access_type=if(is_proc_mem=1, "/proc/pid/mem (direct memory access)", "/proc/pid/maps (memory layout enumeration)")
| eval InjectionRisk=if(is_proc_mem=1, "HIGH - Direct memory write capability", "MEDIUM - Memory layout reconnaissance")
| table _time, host, auid, uid, exe, pid, target_pid, access_type, InjectionRisk
| sort - _timeDetects access to /proc/[pid]/mem and /proc/[pid]/maps via Linux auditd. Distinguishes between memory layout enumeration (maps - reconnaissance) and direct memory access (mem - injection capability). Filters out known system tools that legitimately read procfs. Access to /proc/[pid]/mem enables writing to another process's memory without ptrace, making it a potent injection vector.
Data Sources
Required Sourcetypes
False Positives & Tuning
- System monitoring tools reading /proc/pid/maps for memory statistics
- Container runtimes accessing /proc for cgroup and namespace management
- Performance profiling and tracing tools
- Security tools scanning process memory for malware indicators
Other platforms for T1055.009
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Read Target Process Memory Maps
Expected signal: auditd: open() syscall on /proc/<pid>/maps with the calling process (shell) details. The maps output shows memory regions including stack address needed for injection.
- Test 2DD-based /proc/pid/mem Write Simulation
Expected signal: auditd: open() on /proc/<pid>/maps. In a real injection: write() syscall to /proc/<pid>/mem would be logged. The dd command itself generates process creation events.
- Test 3Check /proc Hardening Configuration
Expected signal: No security telemetry — this is a configuration check. The output shows current hardening level.
References (5)
- https://attack.mitre.org/techniques/T1055/009/
- http://hick.org/code/skape/papers/needle.txt
- https://blog.gdssecurity.com/labs/2017/9/5/linux-based-inter-process-code-injection-without-ptrace2.html
- http://man7.org/linux/man-pages/man1/dd.1.html
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1055.009/T1055.009.md
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