Compressed File Creation Via Tar.EXE

Severity: low
Author: Nasreddine Bencherchali (Nextron Systems), AdmU3
Source: upstream

Detects execution of "tar.exe" in order to create a compressed file. Adversaries may abuse various utilities to compress or encrypt data before exfiltration.

MITRE ATT&CK coverage

Tactic	Techniques
Collection	`T1560` Archive Collected Data, `T1560.001` Archive Collected Data: Archive via Utility

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_img`

or:
Image|endswith: '\tar.exe'
OriginalFileName: bsdtar

Stage 2: `all of selection_create`

or:
CommandLine|contains: -c
CommandLine|contains: -r
CommandLine|contains: -u

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	`-c` corpus 2 (sigma 2) `-r` corpus 3 (sigma 3) `-u` corpus 3 (sigma 3)
`Image`	ends_with	`\tar.exe` corpus 2 (sigma 2)
`OriginalFileName`	eq	`bsdtar` corpus 2 (sigma 2)