Suspicious Eventlog Clearing or Configuration Change Activity

Status: stable
Severity: high
Log source: product windows, category process_creation
Author: Ecco, Daniil Yugoslavskiy, oscd.community, D3F7A5105, Swachchhanda Shrawan Poudel (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the clearing or configuration tampering of EventLog using utilities such as "wevtutil", "powershell" and "wmic". This technique were seen used by threat actors and ransomware strains in order to evade defenses.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1685.001` Disable or Modify Tools: Disable or Modify Windows Event Log, `T1685.005` Disable or Modify Tools: Clear Windows Event Logs

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Suspicious Eventlog Clearing or Configuration Change Activity
id: cc36992a-4671-4f21-a91d-6c2b72a2edf5
status: stable
description: |
    Detects the clearing or configuration tampering of EventLog using utilities such as "wevtutil", "powershell" and "wmic".
    This technique were seen used by threat actors and ransomware strains in order to evade defenses.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1070.001/T1070.001.md
    - https://eqllib.readthedocs.io/en/latest/analytics/5b223758-07d6-4100-9e11-238cfdd0fe97.html
    - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/wevtutil
    - https://gist.github.com/fovtran/ac0624983c7722e80a8f5a4babb170ee
    - https://jdhnet.wordpress.com/2017/12/19/changing-the-location-of-the-windows-event-logs/
    - https://www.linkedin.com/posts/huntress-labs_when-a-sketchy-incident-hits-your-network-activity-7304940371078238208-Th_l/?utm_source=share&utm_medium=member_desktop&rcm=ACoAAAJTlRcB28IaUtg03HUU-IdliwzoAL1flGc
    - https://stackoverflow.com/questions/66011412/how-to-clear-a-event-log-in-powershell-7
    - https://learn.microsoft.com/en-us/dotnet/api/system.diagnostics.eventing.reader.eventlogsession.clearlog?view=windowsdesktop-9.0&viewFallbackFrom=dotnet-plat-ext-5.0#System_Diagnostics_Eventing_Reader_EventLogSession_ClearLog_System_String_
    - https://learn.microsoft.com/en-us/dotnet/api/system.diagnostics.eventlog.clear
author: Ecco, Daniil Yugoslavskiy, oscd.community, D3F7A5105, Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2019-09-26
modified: 2026-06-01
tags:
    - attack.defense-impairment
    - attack.t1685.005
    - attack.t1685.001
    - car.2016-04-002
logsource:
    category: process_creation
    product: windows
detection:
    selection_wevtutil_img:
        - Image|endswith: '\wevtutil.exe'
        - OriginalFileName: 'wevtutil.exe'
    selection_wevtutil_cmd:
        CommandLine|contains:
            - 'clear-log '          # clears specified log
            - ' cl '                # short version of 'clear-log'
            - 'set-log '            # modifies config of specified log. could be used to set it to a tiny size
            - ' sl '                # short version of 'set-log'
            - 'lfn:'                # change log file location and name
    selection_other_ps_img:
        Image|endswith:
            - '\powershell.exe'
            - '\powershell_ise.exe'
            - '\pwsh.exe'
    selection_other_ps_cmd:
        - CommandLine|contains:
              - 'Clear-EventLog '
              - 'Remove-EventLog '
              - 'Limit-EventLog '
              - 'Clear-WinEvent '
        - CommandLine|contains|all:
              - 'Eventing.Reader.EventLogSession' # [System.Diagnostics.Eventing.Reader.EventLogSession]::GlobalSession.ClearLog($_.LogName)
              - 'ClearLog'
        - CommandLine|contains|all:
              - 'Diagnostics.EventLog'
              - 'Clear'
    selection_other_wmi:
        Image|endswith:
            - '\powershell.exe'
            - '\powershell_ise.exe'
            - '\pwsh.exe'
            - '\wmic.exe'
        CommandLine|contains: 'ClearEventLog'
    filter_main_msiexec:
        # Example seen during office update/installation:
        #   ParentImage: C:\Windows\SysWOW64\msiexec.exe
        #   CommandLine: "C:\WINDOWS\system32\wevtutil.exe" sl Microsoft-RMS-MSIPC/Debug /q:true /e:true /l:4 /rt:false
        ParentImage:
            - 'C:\Windows\SysWOW64\msiexec.exe'
            - 'C:\Windows\System32\msiexec.exe'
        CommandLine|contains: ' sl '
    condition: ((all of selection_wevtutil_*) or (all of selection_other_ps_*) or selection_other_wmi) and not 1 of filter_main_*
falsepositives:
    - Admin activity
    - Scripts and administrative tools used in the monitored environment
    - Maintenance activity
level: high

Stages and Predicates

Stage 0: `condition`

((all of selection_wevtutil_*) or (all of selection_other_ps_*) or selection_other_wmi) and not 1 of filter_main_*

Stage 1: `selection_wevtutil_img`

selection_wevtutil_img:
    - Image|endswith: '\wevtutil.exe'
    - OriginalFileName: 'wevtutil.exe'

Stage 2: `selection_wevtutil_cmd`

selection_wevtutil_cmd:
    CommandLine|contains:
        - 'clear-log '
        - ' cl '
        - 'set-log '
        - ' sl '
        - 'lfn:'

Stage 3: `selection_other_ps_img`

selection_other_ps_img:
    Image|endswith:
        - '\powershell.exe'
        - '\powershell_ise.exe'
        - '\pwsh.exe'

Stage 4: `selection_other_ps_cmd`

selection_other_ps_cmd:
    - CommandLine|contains:
          - 'Clear-EventLog '
          - 'Remove-EventLog '
          - 'Limit-EventLog '
          - 'Clear-WinEvent '
    - CommandLine|contains|all:
          - 'Eventing.Reader.EventLogSession'
          - 'ClearLog'
    - CommandLine|contains|all:
          - 'Diagnostics.EventLog'
          - 'Clear'

Stage 5: `selection_other_wmi`

selection_other_wmi:
    Image|endswith:
        - '\powershell.exe'
        - '\powershell_ise.exe'
        - '\pwsh.exe'
        - '\wmic.exe'
    CommandLine|contains: 'ClearEventLog'

Stage 6: `not filter_main_msiexec`

filter_main_msiexec:
    ParentImage:
        - 'C:\Windows\SysWOW64\msiexec.exe'
        - 'C:\Windows\System32\msiexec.exe'
    CommandLine|contains: ' sl '

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`ParentImage`	eq	`C:\Windows\SysWOW64\msiexec.exe`
`ParentImage`	eq	`C:\Windows\System32\msiexec.exe`
`CommandLine`	match	`sl`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`CommandLine`	match	`cl` `sl` `Clear` corpus 4 (sigma 3, kusto 1) `Clear-EventLog` `Clear-WinEvent` `ClearEventLog` corpus 2 (sigma 2) `ClearLog` `Diagnostics.EventLog` `Eventing.Reader.EventLogSession` `Limit-EventLog` `Remove-EventLog` `clear-log` `lfn:` `set-log`
`Image`	ends_with	`\powershell.exe` corpus 182 (sigma 182) `\powershell_ise.exe` corpus 41 (sigma 41) `\pwsh.exe` corpus 168 (sigma 168) `\wevtutil.exe` corpus 9 (sigma 9) `\wmic.exe` corpus 60 (sigma 60)
`OriginalFileName`	eq	`wevtutil.exe` corpus 7 (sigma 5, elastic 1, splunk 1)

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Suspicious Eventlog Clearing or Configuration Change Activity

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_wevtutil_img`

Stage 2: `selection_wevtutil_cmd`

Stage 3: `selection_other_ps_img`

Stage 4: `selection_other_ps_cmd`

Stage 5: `selection_other_wmi`

Stage 6: `not filter_main_msiexec`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Suspicious Eventlog Clearing or Configuration Change Activity

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_wevtutil_img

Stage 2: selection_wevtutil_cmd

Stage 3: selection_other_ps_img

Stage 4: selection_other_ps_cmd

Stage 5: selection_other_wmi

Stage 6: not filter_main_msiexec

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection_wevtutil_img`

Stage 2: `selection_wevtutil_cmd`

Stage 3: `selection_other_ps_img`

Stage 4: `selection_other_ps_cmd`

Stage 5: `selection_other_wmi`

Stage 6: `not filter_main_msiexec`