System Information Discovery - Auditd

Status: test
Severity: low
Log source: product linux, service auditd
Author: Pawel Mazur
Source: github.com/SigmaHQ/sigma

Detects System Information Discovery commands

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1082` System Information Discovery

Event coverage

Provider	Event
Linux-Auditd	Event ID 1302
Linux-Auditd	Event ID 1309

Rule body yaml

title: System Information Discovery - Auditd
id: f34047d9-20d3-4e8b-8672-0a35cc50dc71
status: test
description: Detects System Information Discovery commands
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f296668303c29d3f4c07e42bdd2b28d8dd6625f9/atomics/T1082/T1082.md
author: Pawel Mazur
date: 2021-09-03
modified: 2023-03-06
tags:
    - attack.discovery
    - attack.t1082
logsource:
    product: linux
    service: auditd
detection:
    selection_1:
        type: PATH
        name:
            - /etc/lsb-release
            - /etc/redhat-release
            - /etc/issue
    selection_2:
        type: EXECVE
        a0:
            - uname
            - uptime
            - lsmod
            - hostname
            - env
    selection_3:
        type: EXECVE
        a0: grep
        a1|contains:
            - vbox
            - vm
            - xen
            - virtio
            - hv
    selection_4:
        type: EXECVE
        a0: kmod
        a1: list
    condition: 1 of selection_*
falsepositives:
    - Likely
level: low

Stages and Predicates

Stage 0: `condition`

1 of selection_*

Stage 1: `selection_1`

selection_1:
    type: PATH
    name:
        - /etc/lsb-release
        - /etc/redhat-release
        - /etc/issue

Stage 2: `selection_2`

selection_2:
    type: EXECVE
    a0:
        - uname
        - uptime
        - lsmod
        - hostname
        - env

Stage 3: `selection_3`

selection_3:
    type: EXECVE
    a0: grep
    a1|contains:
        - vbox
        - vm
        - xen
        - virtio
        - hv

Stage 4: `selection_4`

selection_4:
    type: EXECVE
    a0: kmod
    a1: list

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
`a0`	eq	`env` `grep` `hostname` `kmod` `lsmod` `uname` `uptime`
`a1`	eq	`list`
`a1`	match	`hv` `vbox` `virtio` `vm` `xen`
`name`	eq	`/etc/issue` `/etc/lsb-release` `/etc/redhat-release`
`type`	eq	`EXECVE` `PATH`

`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)

System Information Discovery - Auditd

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_1`

Stage 2: `selection_2`

Stage 3: `selection_3`

Stage 4: `selection_4`

Indicators

Keyboard shortcuts

Search operators

System Information Discovery - Auditd

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_1

Stage 2: selection_2

Stage 3: selection_3

Stage 4: selection_4

Indicators

Stage 0: `condition`

Stage 1: `selection_1`

Stage 2: `selection_2`

Stage 3: `selection_3`

Stage 4: `selection_4`