Command Line Execution with Suspicious URL and AppData Strings

Status: test
Severity: medium
Log source: category process_creation, product windows
Author: Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community
Source: github.com/SigmaHQ/sigma

Detects a suspicious command line execution that includes an URL and AppData string in the command line parameters as used by several droppers (js/vbs > powershell)

Known false positives

High

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell `T1059.003` Command and Scripting Interpreter: Windows Command Shell
Command & Control	`T1105` Ingress Tool Transfer

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation
Security-Auditing	Event ID 4688: A new process has been created.

Rule body

title: Command Line Execution with Suspicious URL and AppData Strings
id: 1ac8666b-046f-4201-8aba-1951aaec03a3
status: test
description: Detects a suspicious command line execution that includes an URL and AppData string in the command line parameters as used by several droppers (js/vbs > powershell)
references:
    - https://www.hybrid-analysis.com/sample/3a1f01206684410dbe8f1900bbeaaa543adfcd07368ba646b499fa5274b9edf6?environmentId=100
    - https://www.hybrid-analysis.com/sample/f16c729aad5c74f19784a24257236a8bbe27f7cdc4a89806031ec7f1bebbd475?environmentId=100
author: Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community
date: 2019-01-16
modified: 2021-11-27
tags:
    - attack.execution
    - attack.command-and-control
    - attack.t1059.003
    - attack.t1059.001
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\cmd.exe'
        CommandLine|contains|all:
            - 'http' # captures both http and https
            - '://'
            - '%AppData%'
    condition: selection
falsepositives:
    - High
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    Image|endswith: '\cmd.exe'
    CommandLine|contains|all:
        - 'http'
        - '://'
        - '%AppData%'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`%AppData%` corpus 13 (sigma 11, chronicle 2) `://` corpus 3 (sigma 3) `http` corpus 52 (sigma 34, elastic 15, chronicle 2, splunk 1)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\cmd.exe` corpus 130 (sigma 130)	`field:"Image" kind:ends_with value:"\cmd.exe"`