Analytics Story: Linux Persistence Techniques

Date: 2021-12-17 ID: e40d13e5-d38b-457e-af2a-e8e6a2f2b516 Author: Teoderick Contreras, Splunk Product: Splunk Enterprise Security

Description

Monitor for activities and techniques associated with maintaining persistence on a Linux system--a sign that an adversary may have compromised your environment.

Why it matters

Maintaining persistence is one of the first steps taken by attackers after the initial compromise. Attackers leverage various custom and built-in tools to ensure survivability and persistent access within a compromised enterprise. This Analytic Story provides searches to help you identify various behaviors used by attackers to maintain persistent access to a Linux environment.

Correlation Search

1| tstats `security_content_summariesonly` min(_time) as firstTime max(_time) as lastTime sum(All_Risk.calculated_risk_score) as risk_score, count(All_Risk.calculated_risk_score) as risk_event_count, values(All_Risk.annotations.mitre_attack.mitre_tactic_id) as annotations.mitre_attack.mitre_tactic_id, dc(All_Risk.annotations.mitre_attack.mitre_tactic_id) as mitre_tactic_id_count, values(All_Risk.annotations.mitre_attack.mitre_technique_id) as annotations.mitre_attack.mitre_technique_id, dc(All_Risk.annotations.mitre_attack.mitre_technique_id) as mitre_technique_id_count, values(All_Risk.tag) as tag, values(source) as source, dc(source) as source_count from datamodel=Risk.All_Risk where (All_Risk.analyticstories IN ("Linux Privilege Escalation", "Linux Persistence Techniques") OR source = "*Linux*") All_Risk.annotations.mitre_attack.mitre_tactic IN ("persistence", "privilege-escalation") All_Risk.risk_object_type="system" by All_Risk.risk_object All_Risk.risk_object_type All_Risk.annotations.mitre_attack.mitre_tactic | `drop_dm_object_name(All_Risk)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | where source_count >= 4 | `linux_persistence_and_privilege_escalation_risk_behavior_filter`

Detections

Name ▲▼	Technique ▲▼	Type ▲▼
Linux Add Files In Known Crontab Directories	Cron	Anomaly
Linux Add User Account	Local Account	Hunting
Linux Adding Crontab Using List Parameter	Cron	Hunting
Linux At Allow Config File Creation	Cron	Anomaly
Linux At Application Execution	At	Anomaly
Linux Auditd Add User Account	Local Account	Anomaly
Linux Auditd Add User Account Type	Local Account	Anomaly
Linux Auditd At Application Execution	At	Anomaly
Linux Auditd Auditd Service Stop	Service Stop	Anomaly
Linux Auditd Base64 Decode Files	Deobfuscate/Decode Files or Information	Anomaly
Linux Auditd Change File Owner To Root	Linux and Mac File and Directory Permissions Modification	Anomaly
Linux Auditd Data Transfer Size Limits Via Split	Data Transfer Size Limits	Anomaly
Linux Auditd Data Transfer Size Limits Via Split Syscall	Data Transfer Size Limits	Anomaly
Linux Auditd Database File And Directory Discovery	File and Directory Discovery	Anomaly
Linux Auditd Disable Or Modify System Firewall	Disable or Modify System Firewall	Anomaly
Linux Auditd Doas Conf File Creation	Sudo and Sudo Caching	TTP
Linux Auditd Doas Tool Execution	Sudo and Sudo Caching	Anomaly
Linux Auditd Edit Cron Table Parameter	Cron	Anomaly
Linux Auditd File And Directory Discovery	File and Directory Discovery	Anomaly
Linux Auditd File Permission Modification Via Chmod	Linux and Mac File and Directory Permissions Modification	Anomaly
Linux Auditd File Permissions Modification Via Chattr	Linux and Mac File and Directory Permissions Modification	Anomaly
Linux Auditd Find Credentials From Password Managers	Password Managers	TTP
Linux Auditd Find Credentials From Password Stores	Password Managers	TTP
Linux Auditd Find Ssh Private Keys	Private Keys	Anomaly
Linux Auditd Hidden Files And Directories Creation	File and Directory Discovery	Anomaly
Linux Auditd Insert Kernel Module Using Insmod Utility	Kernel Modules and Extensions	Anomaly
Linux Auditd Install Kernel Module Using Modprobe Utility	Kernel Modules and Extensions	Anomaly
Linux Auditd Kernel Module Using Rmmod Utility	Kernel Modules and Extensions	TTP
Linux Auditd Nopasswd Entry In Sudoers File	Sudo and Sudo Caching	Anomaly
Linux Auditd Osquery Service Stop	Service Stop	Anomaly
Linux Auditd Possible Access Or Modification Of Sshd Config File	SSH Authorized Keys	Anomaly
Linux Auditd Possible Access To Credential Files	/etc/passwd and /etc/shadow	Anomaly
Linux Auditd Possible Access To Sudoers File	Sudo and Sudo Caching	Anomaly
Linux Auditd Possible Append Cronjob Entry On Existing Cronjob File	Cron	Hunting
Linux Auditd Preload Hijack Library Calls	Dynamic Linker Hijacking	TTP
Linux Auditd Preload Hijack Via Preload File	Dynamic Linker Hijacking	TTP
Linux Auditd Private Keys and Certificate Enumeration	Private Keys	Anomaly
Linux Auditd Service Restarted	Systemd Timers	Anomaly
Linux Auditd Service Started	Service Execution	Anomaly
Linux Auditd Setuid Using Chmod Utility	Setuid and Setgid	Anomaly
Linux Auditd Setuid Using Setcap Utility	Setuid and Setgid	TTP
Linux Auditd Shred Overwrite Command	Data Destruction	TTP
Linux Auditd Sudo Or Su Execution	Sudo and Sudo Caching	Anomaly
Linux Auditd Sysmon Service Stop	Service Stop	Anomaly
Linux Auditd System Network Configuration Discovery	System Network Configuration Discovery	Anomaly
Linux Auditd Unix Shell Configuration Modification	Unix Shell Configuration Modification	TTP
Linux Auditd Unload Module Via Modprobe	Kernel Modules and Extensions	TTP
Linux Auditd Virtual Disk File And Directory Discovery	File and Directory Discovery	Anomaly
Linux Auditd Whoami User Discovery	System Owner/User Discovery	Anomaly
Linux Change File Owner To Root	Linux and Mac File and Directory Permissions Modification	Anomaly
Linux Common Process For Elevation Control	Setuid and Setgid	Hunting
Linux Doas Conf File Creation	Sudo and Sudo Caching	Anomaly
Linux Doas Tool Execution	Sudo and Sudo Caching	Anomaly
Linux Edit Cron Table Parameter	Cron	Hunting
Linux File Created In Kernel Driver Directory	Kernel Modules and Extensions	Anomaly
Linux File Creation In Init Boot Directory	RC Scripts	Anomaly
Linux File Creation In Profile Directory	Unix Shell Configuration Modification	Anomaly
Linux Insert Kernel Module Using Insmod Utility	Kernel Modules and Extensions	Anomaly
Linux Install Kernel Module Using Modprobe Utility	Kernel Modules and Extensions	Anomaly
Linux NOPASSWD Entry In Sudoers File	Sudo and Sudo Caching	Anomaly
Linux Possible Access Or Modification Of sshd Config File	SSH Authorized Keys	Anomaly
Linux Possible Access To Credential Files	/etc/passwd and /etc/shadow	Anomaly
Linux Possible Access To Sudoers File	Sudo and Sudo Caching	Anomaly
Linux Possible Append Command To At Allow Config File	At	Anomaly
Linux Possible Append Command To Profile Config File	Unix Shell Configuration Modification	Anomaly
Linux Possible Append Cronjob Entry on Existing Cronjob File	Cron	Hunting
Linux Possible Cronjob Modification With Editor	Cron	Hunting
Linux Possible Ssh Key File Creation	SSH Authorized Keys	Anomaly
Linux Preload Hijack Library Calls	Dynamic Linker Hijacking	TTP
Linux Service File Created In Systemd Directory	Systemd Timers	Anomaly
Linux Service Restarted	Systemd Timers	Anomaly
Linux Service Started Or Enabled	Systemd Timers	Anomaly
Linux Setuid Using Chmod Utility	Setuid and Setgid	Anomaly
Linux Setuid Using Setcap Utility	Setuid and Setgid	Anomaly
Linux Shred Overwrite Command	Data Destruction	TTP
Linux Sudo OR Su Execution	Sudo and Sudo Caching	Hunting
Linux Sudoers Tmp File Creation	Sudo and Sudo Caching	Anomaly
Linux Visudo Utility Execution	Sudo and Sudo Caching	Anomaly

Data Sources

Name ▲▼	Platform ▲▼	Sourcetype ▲▼	Source ▲▼
Linux Auditd Add User	Linux	`auditd`	`auditd`
Linux Auditd Execve	Linux	`auditd`	`auditd`
Linux Auditd Path	Linux	`auditd`	`auditd`
Linux Auditd Proctitle	Linux	`auditd`	`auditd`
Linux Auditd Service Stop	Linux	`auditd`	`auditd`
Linux Auditd Syscall	Linux	`auditd`	`auditd`
Sysmon for Linux EventID 1	Linux	`sysmon:linux`	`Syslog:Linux-Sysmon/Operational`
Sysmon for Linux EventID 11	Linux	`sysmon:linux`	`Syslog:Linux-Sysmon/Operational`

References

Source: GitHub | Version: 1