IMPORTANT: No additional bug fixes or documentation updates
will be released for this version. For the latest information, see the
current release documentation.
Startup or Run Key Registry Modification
editStartup or Run Key Registry Modification
editIdentifies run key or startup key registry modifications. In order to survive reboots and other system interrupts, attackers will modify run keys within the registry or leverage startup folder items as a form of persistence.
Rule type: eql
Rule indices:
- logs-endpoint.events.*
Severity: low
Risk score: 21
Runs every: 5 minutes
Searches indices from: now-9m (Date Math format, see also Additional look-back time
)
Maximum alerts per execution: 100
Tags:
- Elastic
- Host
- Windows
- Threat Detection
- Persistence
Version: 101 (version history)
Added (Elastic Stack release): 7.11.0
Last modified (Elastic Stack release): 8.5.0
Rule authors: Elastic
Rule license: Elastic License v2
Investigation guide
edit## Triage and analysis ### Investigating Startup or Run Key Registry Modification Adversaries may achieve persistence by referencing a program with a registry run key. Adding an entry to the run keys in the registry will cause the program referenced to be executed when a user logs in. These programs will executed under the context of the user and will have the account's permissions. This rule looks for this behavior by monitoring a range of registry run keys. #### 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 process executable 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 task 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 registry run keys. This activity could be based on new software installations, patches, or any kind of network administrator related activity. Before undertaking 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 - Startup Folder Persistence via Unsigned Process - 2fba96c0-ade5-4bce-b92f-a5df2509da3f - Startup Persistence by a Suspicious Process - 440e2db4-bc7f-4c96-a068-65b78da59bde ### 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
editregistry where registry.data.strings != null and registry.path : ( /* Machine Hive */ "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnce\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnceEx\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\Explore r\\Run\\*", "HKLM\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon\\Shell\\*", /* Users Hive */ "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnce\ \*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersion \\RunOnceEx\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\Cu rrentVersion\\Policies\\Explorer\\Run\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon\\Shell\\*" ) and /* add common legitimate changes without being too restrictive as this is one of the most abused AESPs */ not registry.data.strings : "ctfmon.exe /n" and not (registry.value : "Application Restart #*" and process.name : "csrss.exe") and user.id not in ("S-1-5-18", "S-1-5-19", "S-1-5-20") and not registry.data.strings : ("?:\\Program Files\\*.exe", "?:\\Program Files (x86)\\*.exe") and not process.executable : ("?:\\Windows\\System32\\msiexec.exe", "?:\\Windows\\SysWOW64\\msiexec.exe") and not (process.name : "OneDriveSetup.exe" and registry.value : ("Delete Cached Standalone Update Binary", "Delete Cached Update Binary", "amd64", "Uninstall *") and registry.data.strings : "?:\\Windows\\system32\\cmd.exe /q /c * \"?:\\Users\\*\\AppData\\Local\\Microsoft\\OneDrive\\*\"")
Threat mapping
editFramework: 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/
Rule version history
edit- Version 101 (8.5.0 release)
-
-
Updated query, changed from:
registry where registry.data.strings != null and registry.path : ( /* Machine Hive */ "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnce\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnceEx\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\Explore r\\Run\\*", "HKLM\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon\\Shell\\*", /* Users Hive */ "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnce\ \*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersio n\\RunOnceEx\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\C urrentVersion\\Policies\\Explorer\\Run\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon\\Shell\\*" ) and /* add common legitimate changes without being too restrictive as this is one of the most abused AESPs */ not registry.data.strings : "ctfmon.exe /n" and not (registry.value : "Application Restart #*" and process.name : "csrss.exe") and user.id not in ("S-1-5-18", "S-1-5-19", "S-1-5-20") and not registry.data.strings : ("?:\\Program Files\\*.exe", "?:\\Program Files (x86)\\*.exe") and not process.executable : ("?:\\Windows\\System32\\msiexec.exe", "?:\\Windows\\SysWOW64\\msiexec.exe") and not (process.name : "OneDriveSetup.exe" and registry.value : ("Delete Cached Standalone Update Binary", "Delete Cached Update Binary", "amd64", "Uninstall *") and registry.data.strings : "?:\\Windows\\system32\\cmd.exe /q /c * \"?:\\Users\\*\\AppData\\Local\\Microsoft\\OneDrive\\*\"")
-
- Version 9 (8.4.0 release)
-
- Formatting only
- Version 8 (8.3.0 release)
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- Formatting only
- Version 6 (8.2.0 release)
-
- Formatting only
- Version 5 (8.1.0 release)
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- Formatting only
- Version 4 (7.13.0 release)
-
-
Updated query, changed from:
/* uncomment length once stable */ registry where /* length(registry.data.strings) > 0 and */ registry.path : ( /* Machine Hive */ "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnce\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnceEx\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\User Shell Folders\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders\\*", "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion \\Policies\\Explorer\\Run\\*", "HKLM\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon\\Shell\\*", /* Users Hive */ "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnce\ \*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\CurrentVersio n\\RunOnceEx\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\ CurrentVersion\\Explorer\\User Shell Folders\\*", "HKEY_USERS\\* \\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows\\Curre ntVersion\\Policies\\Explorer\\Run\\*", "HKEY_USERS\\*\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon\\Shell\\*" ) and /* add here common legit changes without making too restrictive as this is one of the most abused AESPs */ not registry.data.strings : "ctfmon.exe /n" and not (registry.value : "Application Restart #*" and process.name : "csrss.exe") and user.domain != "NT AUTHORITY" and not registry.data.strings : ("C:\\Program Files\\*.exe", "C:\\Program Files (x86)\\*.exe") and not process.executable : ("C:\\Windows\\System32\\msiexec.exe", "C:\\Windows\\SysWOW64\\msiexec.exe")
-
- Version 3 (7.12.0 release)
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- Formatting only
- Version 2 (7.11.2 release)
-
- Formatting only