Techniques
Sample rules
Cloud Security Groups Modifications by User
- source: splunk
- technicques:
- T1578.005
Description
The following analytic identifies users who are unsually modifying security group in your cloud enriovnment,focusing on actions such as modifications, deletions, or creations performed by users over 30-minute intervals. Analyzing patterns of modifications to security groups can help in identifying anomalous behavior that may indicate a compromised account or an insider threat.
The detection calculates the standard deviation for each host and leverages the 3-sigma statistical rule to identify an unusual number of users. To customize this analytic, users can try different combinations of the bucket span time and the calculation of the upperBound field. This logic can be used for real time security monitoring as well as threat hunting exercises.
This detection will only trigger on all user and service accounts that have created/modified/deleted a security group .
The analytics returned fields allow analysts to investigate the event further by providing fields like source ip and values of the security objects affected.
Detection logic
| tstats dc(All_Changes.object) as unique_security_groups values(All_Changes.src) as src values(All_Changes.user_type) as user_type values(All_Changes.object_category) as object_category values(All_Changes.object) as objects values(All_Changes.action) as action values(All_Changes.user_agent) as user_agent values(All_Changes.command) as command from datamodel=Change WHERE All_Changes.object_category = "security_group" (All_Changes.action = modified OR All_Changes.action = deleted OR All_Changes.action = created) by All_Changes.user _time span=30m
| `drop_dm_object_name("All_Changes")`
| eventstats avg(unique_security_groups) as avg_changes , stdev(unique_security_groups) as std_changes by user
| eval upperBound=(avg_changes+std_changes*3)
| eval isOutlier=if(unique_security_groups > 2 and unique_security_groups >= upperBound, 1, 0)
| where isOutlier=1
| `cloud_security_groups_modifications_by_user_filter`