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security: harden Claude Code Actions against prompt injection (Comment and Control) #271

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security: harden Claude Code Actions against prompt injection (Comment and Control) #271

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24 changes: 9 additions & 15 deletions .github/workflows/claude-code-review.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -3,27 +3,22 @@ name: Claude Code Review
on:
pull_request:
types: [opened, synchronize, ready_for_review, reopened]
# Optional: Only run on specific file changes
# paths:
# - "src/**/*.ts"
# - "src/**/*.tsx"
# - "src/**/*.js"
# - "src/**/*.jsx"

jobs:
claude-review:
# Optional: Filter by PR author
# if: |
# github.event.pull_request.user.login == 'external-contributor' ||
# github.event.pull_request.user.login == 'new-developer' ||
# github.event.pull_request.author_association == 'FIRST_TIME_CONTRIBUTOR'
# HARDENED (Comment and Control vulnerability — 2026-04-21)
# Only run for trusted PR authors. Untrusted forks cannot trigger this.
if: |
github.event.pull_request.user.login == 'zerodarkthirtyhq' ||
github.event.pull_request.author_association == 'OWNER' ||
github.event.pull_request.author_association == 'MEMBER'

runs-on: ubuntu-latest
# Least-privilege permissions — removed id-token:write (not needed)
permissions:
contents: read
pull-requests: read
issues: read
id-token: write

steps:
- name: Checkout repository
Expand All @@ -39,6 +34,5 @@ jobs:
plugin_marketplaces: 'https://github.com/anthropics/claude-code.git'
plugins: 'code-review@claude-code-plugins'
prompt: '/code-review:code-review ${{ github.repository }}/pull/${{ github.event.pull_request.number }}'
# See https://github.com/anthropics/claude-code-action/blob/main/docs/usage.md
# or https://code.claude.com/docs/en/cli-reference for available options

# HARDENED: Restrict dangerous tools to prevent prompt injection exploitation
claude_args: '--disallowed-tools Bash,Write,WebFetch,Edit,NotebookEdit'
30 changes: 14 additions & 16 deletions .github/workflows/claude.yml
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Expand Up @@ -12,17 +12,24 @@ on:

jobs:
claude:
# HARDENED (Comment and Control vulnerability — 2026-04-21)
# Require @claude mention AND trusted actor. Untrusted users cannot trigger.
if: |
(github.event_name == 'issue_comment' && contains(github.event.comment.body, '@claude')) ||
(github.event_name == 'pull_request_review_comment' && contains(github.event.comment.body, '@claude')) ||
(github.event_name == 'pull_request_review' && contains(github.event.review.body, '@claude')) ||
(github.event_name == 'issues' && (contains(github.event.issue.body, '@claude') || contains(github.event.issue.title, '@claude')))
(
(github.event_name == 'issue_comment' && contains(github.event.comment.body, '@claude')) ||
(github.event_name == 'pull_request_review_comment' && contains(github.event.comment.body, '@claude')) ||
(github.event_name == 'pull_request_review' && contains(github.event.review.body, '@claude')) ||
(github.event_name == 'issues' && (contains(github.event.issue.body, '@claude') || contains(github.event.issue.title, '@claude')))
) && (
github.actor == 'zerodarkthirtyhq' ||
github.event.sender.login == 'zerodarkthirtyhq'
)
runs-on: ubuntu-latest
# Least-privilege — removed id-token:write (not needed)
permissions:
contents: read
pull-requests: read
issues: read
id-token: write
actions: read # Required for Claude to read CI results on PRs
steps:
- name: Checkout repository
Expand All @@ -35,16 +42,7 @@ jobs:
uses: anthropics/claude-code-action@v1
with:
claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}

# This is an optional setting that allows Claude to read CI results on PRs
additional_permissions: |
actions: read

# Optional: Give a custom prompt to Claude. If this is not specified, Claude will perform the instructions specified in the comment that tagged it.
# prompt: 'Update the pull request description to include a summary of changes.'

# Optional: Add claude_args to customize behavior and configuration
# See https://github.com/anthropics/claude-code-action/blob/main/docs/usage.md
# or https://code.claude.com/docs/en/cli-reference for available options
# claude_args: '--allowed-tools Bash(gh pr:*)'

# HARDENED: Restrict dangerous tools to prevent prompt injection exploitation
claude_args: '--disallowed-tools Bash,Write,WebFetch,Edit,NotebookEdit'