PH_Rule_TH_EQLLIB_LINUX_16
Enabled
Detect modification of .bash_profile and .bashrc files for persistent commands
7
Security
Persistence
Persistence consists of techniques that adversaries use to keep access to systems across restarts, changed credentials, and other interruptions that could cut off their access. Techniques used for persistence include any access, action, or configuration changes that let them maintain their foothold on systems, such as replacing or hijacking legitimate code or adding startup code.
https://attack.mitre.org/tactics/TA0003T1546.004
Event Triggered Execution: Unix Shell Configuration Modification
Adversaries may establish persistence by executing malicious content triggered by a user's shell.?~/.bash_profile?and?~/.bashrc?are shell scripts that contain shell commands. These files are executed in a user's context when a new shell opens or when a user logs in so that their environment is set correctly. Adversaries may abuse these shell scripts by inserting arbitrary shell commands that may be used to execute other binaries to gain persistence.
https://attack.mitre.org/techniques/T1546/004Server
Linux File Monitoring via FortiSIEM Agent
Correlation
No remediation guidance specified
If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.
300 seconds
If the following defined pattern/s occur within a 300 second time window.
Filter
This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.
This is the query logic that matches incoming events
eventType = "FSM_LINUX_FILE_MODIFY" AND (targetOsObjName REGEXP "\.bash_profile|\.bashrc")
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
hostName,targetOsObjName
This is most typically a numerical constraint that defines when the rule should trigger an incident
COUNT(*) >= 1
This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.
The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern
hostName = Filter.hostName,
targetOsObjName = Filter.targetOsObjName