Visual Studio Code Tunnel Shell Execution

Severity: medium
Author: Nasreddine Bencherchali (Nextron Systems)
Source: upstream

Detects the execution of a shell (powershell, bash, wsl...) via Visual Studio Code tunnel. Attackers can abuse this functionality to establish a C2 channel and execute arbitrary commands on the system.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1071.001` Application Layer Protocol: Web Protocols

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `selection_parent`

ParentCommandLine|contains: .vscode-server
ParentImage|endswith: '\server\node.exe'
ParentImage|contains: '\servers\Stable-'

Stage 2: `1 of selection_child_1`

or:
Image|endswith: '\powershell.exe'
Image|endswith: '\pwsh.exe'
CommandLine|contains: '\terminal\browser\media\shellIntegration.ps1'

Stage 3: `1 of selection_child_2`

or:
Image|endswith: '\bash.exe'
Image|endswith: '\wsl.exe'

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	`\terminal\browser\media\shellIntegration.ps1`
`Image`	ends_with	`\bash.exe` corpus 17 (sigma 17) `\powershell.exe` corpus 143 (sigma 143) `\pwsh.exe` corpus 140 (sigma 140) `\wsl.exe` corpus 8 (sigma 8)
`ParentCommandLine`	match	`.vscode-server`
`ParentImage`	ends_with	`\server\node.exe`
`ParentImage`	match	`\servers\Stable-`