Identifies suspicious startup shell folder modifications to change the default Startup directory in order to bypass detections monitoring file creation in the Windows Startup folder.
Rule type: eql
Risk score: 73
Runs every: 5 minutes
Maximum alerts per execution: 100
- Threat Detection
Version: 2 (version history)
Added (Elastic Stack release): 7.13.0
Last modified (Elastic Stack release): 7.16.0
Rule authors: Elastic
Rule license: Elastic License v2
## Triage and analysis ### Investigating Suspicious Startup Shell Activity Techniques used within malware and by adversaries often leverage the Windows registry to store malicious programs for persistence. Startup shell folders are often targeted as they are not as prevalent as normal Startup folder paths so this behavior may evade existing AV/EDR solutions. Another preference is that these programs might run with higher privileges which can be ideal for an attacker. #### Possible investigation steps: - Review the source process and related file tied to the Windows Registry entry - Validate the activity is not related to planned patches, updates, network administrator activity or legitimate software installations - Determine if activity is unique by validating if other machines in same organization have similar entry ### False Positive Analysis - There is a high possibility of benign legitimate programs being added to Shell folders. This activity could be based on new software installations, patches, or any kind of network administrator related activity. Before entering further investigation, this activity should be validated that is it not related to benign activity ### Related Rules - Startup or Run Key Registry Modification - Persistent Scripts in the Startup Directory ### Response and Remediation - Activity should first be validated as a true positive event if so then immediate response should be taken to review, investigate and potentially isolate activity to prevent further post-compromise behavior - The respective binary or program tied to this persistence method should be further analyzed and reviewed to understand it's behavior and capabilities - Since this activity is considered post-exploitation behavior, it's important to understand how the behavior was first initialized such as through a macro-enabled document that was attached in a phishing email. By understanding the source of the attack, this information can then be used to search for similar indicators on other machines in the same environment.
registry where registry.path : ( "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\User Shell Folders\\Common Startup", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders\\Common Startup", "HKEY_USERS\\*\\Software\\Microsoft\\Wi ndows\\CurrentVersion\\Explorer\\User Shell Folders\\Startup", "H KEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\ Shell Folders\\Startup" ) and registry.data.strings != null and /* Normal Startup Folder Paths */ not registry.data.strings : ( "C:\\ProgramData\\Microsoft\\Windows\\Start Menu\\Programs\\Startup", "%ProgramData%\\Microsoft\\Windows\\Start Menu\\Programs\\Startup", "%USERPROFILE%\\AppData\\Roaming\\Microsoft\\Windows\\Start Menu\\Programs\\Startup", "C:\\Users\\*\\AppData\\Roaming\\Microsoft\\Windows\\Start Menu\\Programs\\Startup" )
Framework: MITRE ATT&CKTM
- Version 2 (7.16.0 release)
- Formatting only