Detect Proc Filesystem in Splunk
Adversaries on Linux systems read process memory directly via the /proc filesystem to extract credentials from running processes. By accessing /proc/<PID>/maps to identify memory regions and /proc/<PID>/mem to read those regions, attackers dump credentials from processes like sshd, su, sudo, gnome-keyring, and KWallet without injecting code or using ptrace. Tools include MimiPenguin (specifically targeting sshd and gnome-keyring), LaZagne (Linux edition), and PACEMAKER. This technique requires root privileges or the same UID as the target process. Used by threat actors targeting Linux servers where traditional Windows credential tools don't apply.
MITRE ATT&CK
- Tactic
- Credential Access
- Technique
- T1003 OS Credential Dumping
- Sub-technique
- T1003.007 Proc Filesystem
- Canonical reference
- https://attack.mitre.org/techniques/T1003/007/
SPL Detection Query
index=linux_logs
(sourcetype="linux_auditd" OR sourcetype="auditd")
(syscall=open OR syscall=openat OR syscall=read)
(name="/proc/*/mem" OR name="/proc/*/maps" OR name="/proc/*/environ")
NOT (exe="/usr/bin/gdb" OR exe="/usr/bin/strace" OR exe="/usr/bin/cat")
| eval proc_pid=replace(name, "/proc/(\d+)/.*", "\1")
| eval suspicious=if(match(exe, "python|perl|ruby|bash") AND match(name, "/proc/\d+/mem"), "HighRisk", "Review")
| table _time, host, exe, uid, pid, proc_pid, name, suspicious
| sort - _time
| union
[search index=linux_logs sourcetype="linux_secure" OR sourcetype="syslog"
("mimipenguin" OR "MimiPenguin" OR "lazagne" OR "PACEMAKER")
| table _time, host, process, message
| sort - _time]Detects Linux /proc filesystem memory access via auditd syscall events for open/read on /proc/<PID>/mem and /proc/<PID>/maps paths, with process executable context to identify scripting engines accessing process memory. Also catches tool name signatures for MimiPenguin, LaZagne Linux, and PACEMAKER in syslog.
Data Sources
Required Sourcetypes
False Positives & Tuning
- GDB, strace, or ltrace accessing /proc/<PID>/mem for legitimate debugging sessions
- Performance profilers (perf, pprof) reading process maps to resolve stack frames
- Application monitoring agents (Datadog, New Relic) using /proc for metric collection
- Core dump utilities reading process memory after crashes (systemd-coredump, apport)
- Container introspection tools reading /proc for namespace and cgroup information
Other platforms for T1003.007
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 1MimiPenguin Linux Credential Dump
Expected signal: Auditd SYSCALL events for openat on /proc/<PID>/mem with exe=/usr/bin/python3. DeviceFileEvents (if MDE Linux agent present) for /proc/*/mem access by python3. Syslog entries if gnome-keyring or sshd crash due to memory access attempt.
- Test 2Manual /proc/mem Credential Extraction
Expected signal: Auditd SYSCALL openat events for /proc/<PID>/maps with exe=/bin/cat or /bin/bash. Process creation event for pgrep sshd. DeviceProcessEvents for pgrep and cat with /proc path arguments.
- Test 3LaZagne Linux Memory Module
Expected signal: DeviceProcessEvents for lazagne binary execution with 'memory' argument. Auditd execve event for /tmp/lazagne. Auditd openat events for /proc/*/mem if memory module runs. Network connection to GitHub for download (DeviceNetworkEvents).
References (6)
- https://attack.mitre.org/techniques/T1003/007/
- https://github.com/huntergregal/mimipenguin
- https://github.com/AlessandroZ/LaZagne
- https://security.stackexchange.com/questions/91040/what-is-proc-pid-mem
- https://www.slideshare.net/roottoor1/linux-credential-access-techniques
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1003.007/T1003.007.md
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