Remote File Download Via Findstr.EXE

Severity: medium
Author: Furkan CALISKAN, @caliskanfurkan_, @oscd_initiative, Nasreddine Bencherchali (Nextron Systems)
Source: upstream

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
Defense Evasion	`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 ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `selection_findstr`

or:
CommandLine|contains: findstr
Image|endswith: findstr.exe
OriginalFileName: FINDSTR.EXE

Stage 2: `all of selection_cli_download_1`

CommandLine|contains: ' -v '

Stage 3: `all of selection_cli_download_2`

CommandLine|contains: ' -l '

Stage 4: `all of 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` `-v` `\\\\` corpus 7 (sigma 7) `findstr` corpus 3 (sigma 3)
`Image`	ends_with	`findstr.exe` corpus 2 (sigma 2)
`OriginalFileName`	eq	`FINDSTR.EXE` corpus 10 (sigma 10)

Remote File Download Via Findstr.EXE

MITRE ATT&CK coverage

Event coverage

Stages and Predicates

Stage 1: selection_findstr

Stage 2: all of selection_cli_download_1

Stage 3: all of selection_cli_download_2

Stage 4: all of selection_cli_download_3

Indicators

Stage 1: `selection_findstr`

Stage 2: `all of selection_cli_download_1`

Stage 3: `all of selection_cli_download_2`

Stage 4: `all of selection_cli_download_3`