Remote File Download Via Findstr.EXE

Status: test
Severity: medium
Log source: product windows, category process_creation
Author: Furkan CALISKAN, @caliskanfurkan_, @oscd_initiative, Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects execution of "findstr" with specific flags and a remote share path. This specific set of CLI flags would allow "findstr" to download the content of the file located on the remote share as described in the LOLBAS entry.

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1218` System Binary Proxy Execution, `T1564.004` Hide Artifacts: NTFS File Attributes
Credential Access	`T1552.001` Unsecured Credentials: Credentials In Files
Command & Control	`T1105` Ingress Tool Transfer

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Remote File Download Via Findstr.EXE
id: 587254ee-a24b-4335-b3cd-065c0f1f4baa
related:
    - id: bf6c39fc-e203-45b9-9538-05397c1b4f3f
      type: obsolete
status: test
description: |
    Detects execution of "findstr" with specific flags and a remote share path. This specific set of CLI flags would allow "findstr" to download the content of the file located on the remote share as described in the LOLBAS entry.
references:
    - https://lolbas-project.github.io/lolbas/Binaries/Findstr/
    - https://oddvar.moe/2018/04/11/putting-data-in-alternate-data-streams-and-how-to-execute-it-part-2/
    - https://gist.github.com/api0cradle/cdd2d0d0ec9abb686f0e89306e277b8f
author: Furkan CALISKAN, @caliskanfurkan_, @oscd_initiative, Nasreddine Bencherchali (Nextron Systems)
date: 2020-10-05
modified: 2024-03-05
tags:
    - attack.credential-access
    - attack.command-and-control
    - attack.stealth
    - attack.t1218
    - attack.t1564.004
    - attack.t1552.001
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection_findstr:
        - CommandLine|contains: findstr
        - Image|endswith: 'findstr.exe'
        - OriginalFileName: 'FINDSTR.EXE'
    selection_cli_download_1:
        CommandLine|contains|windash: ' -v '
    selection_cli_download_2:
        CommandLine|contains|windash: ' -l '
    selection_cli_download_3:
        CommandLine|contains: '\\\\'
    condition: selection_findstr and all of selection_cli_download_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

selection_findstr and all of selection_cli_download_*

Stage 1: `selection_findstr`

selection_findstr:
    - CommandLine|contains: findstr
    - Image|endswith: 'findstr.exe'
    - OriginalFileName: 'FINDSTR.EXE'

Stage 2: `selection_cli_download_1`

selection_cli_download_1:
    CommandLine|contains|windash: ' -v '

Stage 3: `selection_cli_download_2`

selection_cli_download_2:
    CommandLine|contains|windash: ' -l '

Stage 4: `selection_cli_download_3`

selection_cli_download_3:
    CommandLine|contains: '\\\\'

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	`-l` transforms: `windash` corpus 3 (sigma 3) `-v` transforms: `windash` `\\\\` corpus 6 (sigma 5, splunk 1) `findstr` corpus 8 (sigma 6, splunk 2)
`Image`	ends_with	`findstr.exe` corpus 2 (sigma 2)
`OriginalFileName`	eq	`FINDSTR.EXE` corpus 12 (sigma 12)

`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)

Remote File Download Via Findstr.EXE

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_findstr`

Stage 2: `selection_cli_download_1`

Stage 3: `selection_cli_download_2`

Stage 4: `selection_cli_download_3`

Indicators

Keyboard shortcuts

Search operators

Remote File Download Via Findstr.EXE

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_findstr

Stage 2: selection_cli_download_1

Stage 3: selection_cli_download_2

Stage 4: selection_cli_download_3

Indicators

Stage 0: `condition`

Stage 1: `selection_findstr`

Stage 2: `selection_cli_download_1`

Stage 3: `selection_cli_download_2`

Stage 4: `selection_cli_download_3`