Unusual File Modification by dns.exe
editUnusual File Modification by dns.exe
editIdentifies an unexpected file being modified by dns.exe, the process responsible for Windows DNS Server services, which may indicate activity related to remote code execution or other forms of exploitation.
Rule type: eql
Rule indices:
- winlogbeat-*
- logs-endpoint.events.*
- logs-windows.*
Severity: high
Risk score: 73
Runs every: 5 minutes
Searches indices from: now-9m (Date Math format, see also Additional look-back time
)
Maximum alerts per execution: 100
References:
Tags:
- Elastic
- Host
- Windows
- Threat Detection
- Initial Access
Version: 5 (version history)
Added (Elastic Stack release): 7.10.0
Last modified (Elastic Stack release): 7.13.0
Rule authors: Elastic
Rule license: Elastic License v2
Investigation guide
editTriage and analysis
Investigating Unusual File Write
Detection alerts from this rule indicate potential unusual/abnormal file writes from the DNS Server service process (dns.exe
) after exploitation from CVE-2020-1350 (SigRed) has occurred. Here are some possible avenues of investigation:
- Post-exploitation, adversaries may write additional files or payloads to the system as additional discovery/exploitation/persistence mechanisms.
- Any suspicious or abnormal files written from dns.exe
should be reviewed and investigated with care.
Rule query
editfile where process.name : "dns.exe" and event.type in ("creation", "deletion", "change") and not file.name : "dns.log"
Threat mapping
editFramework: MITRE ATT&CKTM
-
Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
-
Technique:
- Name: External Remote Services
- ID: T1133
- Reference URL: https://attack.mitre.org/techniques/T1133/
Rule version history
edit- Version 5 (7.13.0 release)
-
-
Updated query, changed from:
event.category:file and process.name:dns.exe and event.type:(creation or deletion or change) and not file.name:dns.log
-
- Version 4 (7.12.0 release)
-
- Formatting only
- Version 3 (7.11.2 release)
-
- Formatting only
- Version 2 (7.11.0 release)
-
-
Updated query, changed from:
event.category:file and process.name:dns.exe and not file.name:dns.log
-