IMPORTANT: No additional bug fixes or documentation updates
will be released for this version. For the latest information, see the
current release documentation.
Startup Folder Persistence via Unsigned Process
editStartup Folder Persistence via Unsigned Process
editIdentifies files written or modified in the startup folder by unsigned processes. Adversaries may abuse this technique to maintain persistence in an environment.
Rule type: eql
Rule indices:
- logs-endpoint.events.*
Severity: medium
Risk score: 47
Runs every: 5m
Searches indices from: now-9m (Date Math format, see also Additional look-back time
)
Maximum alerts per execution: 100
References: None
Tags:
- Elastic
- Host
- Windows
- Threat Detection
- Persistence
Version: 100
Rule authors:
- Elastic
Rule license: Elastic License v2
Investigation guide
edit## Triage and analysis ### Investigating Startup Folder Persistence via Unsigned Process The Windows Startup folder is a special folder in Windows. Programs added to this folder are executed during account logon, without user interaction, providing an excellent way for attackers to maintain persistence. This rule looks for unsigned processes writing to the Startup folder locations. #### Possible investigation steps - Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures. - Investigate other alerts associated with the user/host during the past 48 hours. - Validate the activity is not related to planned patches, updates, network administrator activity, or legitimate software installations. - Assess whether this behavior is prevalent in the environment by looking for similar occurrences across hosts. - Retrieve the file and determine if it is malicious: - Use a private sandboxed malware analysis system to perform analysis. - Observe and collect information about the following activities: - Attempts to contact external domains and addresses. - File and registry access, modification, and creation activities. - Service creation and launch activities. - Scheduled tasks creation. - Use the PowerShell Get-FileHash cmdlet to get the files' SHA-256 hash values. - Search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc. ### False positive analysis - There is a high possibility of benign legitimate programs being added to Startup folders. This activity could be based on new software installations, patches, or any kind of network administrator related activity. Before entering further investigation, verify that this activity is not benign. ### Related rules - Suspicious Startup Shell Folder Modification - c8b150f0-0164-475b-a75e-74b47800a9ff - Persistent Scripts in the Startup Directory - f7c4dc5a-a58d-491d-9f14-9b66507121c0 ### Response and remediation - Initiate the incident response process based on the outcome of the triage. - Isolate the involved host to prevent further post-compromise behavior. - If the triage identified malware, search the environment for additional compromised hosts. - Implement temporary network rules, procedures, and segmentation to contain the malware. - Stop suspicious processes. - Immediately block the identified indicators of compromise (IoCs). - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that attackers could use to reinfect the system. - Remove and block malicious artifacts identified during triage. - Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business systems, and web services. - Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components. - Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector. - Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the mean time to respond (MTTR).
Rule query
editsequence by host.id, process.entity_id with maxspan=5s [process where event.type in ("start", "process_started") and process.code_signature.trusted == false and /* suspicious paths can be added here */ process.executable : ("C:\\Users\\*.exe", "C:\\ProgramData\\*.exe", "C:\\Windows\\Temp\\*.exe", "C:\\Windows\\Tasks\\*.exe", "C:\\Intel\\*.exe", "C:\\PerfLogs\\*.exe") ] [file where event.type != "deletion" and user.domain != "NT AUTHORITY" and file.path : ("C:\\Users\\*\\AppData\\Roaming\\Microsoft\\Windows\\Start Menu\\Programs\\Startup\\*", "C:\\ProgramData\\Microsoft\\Windows\\Start Menu\\Programs\\StartUp\\*") ]
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
-
Technique:
- Name: Boot or Logon Autostart Execution
- ID: T1547
- Reference URL: https://attack.mitre.org/techniques/T1547/
-
Sub-technique:
- Name: Registry Run Keys / Startup Folder
- ID: T1547.001
- Reference URL: https://attack.mitre.org/techniques/T1547/001/