Potential Credential Dumping Activity Via LSASS

Status: test
Severity: medium
Log source: product windows, category process_access
Author: Samir Bousseaden, Michael Haag
Source: github.com/SigmaHQ/sigma

Detects process access requests to the LSASS process with specific call trace calls and access masks. This behaviour is expressed by many credential dumping tools such as Mimikatz, NanoDump, Invoke-Mimikatz, Procdump and even the Taskmgr dumping feature.

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1003.001` OS Credential Dumping: LSASS Memory

Event coverage

Provider	Event	Title
Sysmon	Event ID 10	ProcessAccess

Rule body yaml

title: Potential Credential Dumping Activity Via LSASS
id: 5ef9853e-4d0e-4a70-846f-a9ca37d876da
status: test
description: |
    Detects process access requests to the LSASS process with specific call trace calls and access masks.
    This behaviour is expressed by many credential dumping tools such as Mimikatz, NanoDump, Invoke-Mimikatz, Procdump and even the Taskmgr dumping feature.
references:
    - https://web.archive.org/web/20230329170326/https://blog.menasec.net/2019/02/threat-hunting-21-procdump-or-taskmgr.html
    - https://web.archive.org/web/20230208123920/https://cyberwardog.blogspot.com/2017/03/chronicles-of-threat-hunter-hunting-for_22.html
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1003.001/T1003.001.md
    - https://research.splunk.com/endpoint/windows_possible_credential_dumping/
author: Samir Bousseaden, Michael Haag
date: 2019-04-03
modified: 2024-03-02
tags:
    - attack.credential-access
    - attack.t1003.001
    - attack.s0002
logsource:
    category: process_access
    product: windows
detection:
    selection:
        TargetImage|endswith: '\lsass.exe'
        GrantedAccess|contains:
            - '0x1038'
            - '0x1438'
            - '0x143a'
            - '0x1fffff' # Too many false positives
            # - '0x01000'  # Too many false positives
            # - '0x1010'   # Too many false positives
            # - '0x1400'  # Too many false positives
            # - '0x1410' # Too many false positives
            # - '0x40'   # Too many false positives
        CallTrace|contains:
            - 'dbgcore.dll'
            - 'dbghelp.dll'
            - 'kernel32.dll'
            - 'kernelbase.dll'
            - 'ntdll.dll'
    filter_main_system_user:
        SourceUser|contains: # Covers many language settings
            - 'AUTHORI'
            - 'AUTORI'
    filter_optional_thor:
        CallTrace|contains|all:
            - ':\Windows\Temp\asgard2-agent\'
            - '\thor\thor64.exe+'
            - '|UNKNOWN('
        GrantedAccess: '0x103800'
    filter_optional_sysmon:
        SourceImage|endswith: ':\Windows\Sysmon64.exe'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: `selection`

selection:
    TargetImage|endswith: '\lsass.exe'
    GrantedAccess|contains:
        - '0x1038'
        - '0x1438'
        - '0x143a'
        - '0x1fffff'
    CallTrace|contains:
        - 'dbgcore.dll'
        - 'dbghelp.dll'
        - 'kernel32.dll'
        - 'kernelbase.dll'
        - 'ntdll.dll'

Stage 2: `not filter_main_system_user`

filter_main_system_user:
    SourceUser|contains:
        - 'AUTHORI'
        - 'AUTORI'

Stage 3: `not filter_optional_*`

filter_optional_thor:
    CallTrace|contains|all:
        - ':\Windows\Temp\asgard2-agent\'
        - '\thor\thor64.exe+'
        - '|UNKNOWN('
    GrantedAccess: '0x103800'
filter_optional_sysmon:
    SourceImage|endswith: ':\Windows\Sysmon64.exe'

Exclusions

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

Field	Kind	Excluded values
`SourceUser`	match	`AUTHORI`
`SourceUser`	match	`AUTORI`
`CallTrace`	match	`:\Windows\Temp\asgard2-agent\`
`CallTrace`	match	`\thor\thor64.exe+`
`CallTrace`	match	`\|UNKNOWN(`
`GrantedAccess`	eq	`0x103800`
`SourceImage`	ends_with	`:\Windows\Sysmon64.exe`

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
`CallTrace`	match	`dbgcore.dll` corpus 4 (sigma 2, splunk 1, kusto 1) `dbghelp.dll` corpus 4 (sigma 2, splunk 1, kusto 1) `kernel32.dll` `kernelbase.dll` `ntdll.dll`
`GrantedAccess`	match	`0x1038` `0x1438` `0x143a` `0x1fffff`
`TargetImage`	ends_with	`\lsass.exe` corpus 16 (sigma 16)

`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)

Potential Credential Dumping Activity Via LSASS

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_system_user`

Stage 3: `not filter_optional_*`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Potential Credential Dumping Activity Via LSASS

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_main_system_user

Stage 3: not filter_optional_*

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_system_user`

Stage 3: `not filter_optional_*`