The tj-actions/changed-files workflow allows for command injection in changed filenames, allowing an attacker to execute arbitrary code and potentially leak secrets.
Details
The changed-files action returns a list of files changed in a commit or pull request which provides an escape_json input enabled by default, only escapes " for JSON values.
This could potentially allow filenames that contain special characters such as ; and ` (backtick) which can be used by an attacker to take over the GitHub Runner if the output value is used in a raw fashion (thus being directly replaced before execution) inside a run block. By running custom commands an attacker may be able to steal secrets such as GITHUB_TOKEN if triggered on other events than pull_request. For example on push.
Proof of Concept
Submit a pull request to a repository with a new file injecting a command. For example $(whoami).txt which is a valid filename.
Upon approval of the workflow (triggered by the pull request), the action will get executed and the malicious pull request filename will flow into the List all changed files step below.
- name: List all changed files
run: |
for file in $; do
echo "$file was changed"
done
Example output:
##[group]Run for file in $(whoami).txt; do
for file in $(whoami).txt; do
echo "$file was changed"
done
shell: /usr/bin/bash -e {0}
##[endgroup]
runner.txt was changed
Impact
This issue may lead to arbitrary command execution in the GitHub Runner.
Resolution
A new safe_output input would be enabled by default and return filename paths escaping special characters like ;, ` (backtick), $, (), etc for bash environments.
A safe recommendation of using environment variables to store unsafe outputs.
- name: List all changed files
env:
ALL_CHANGED_FILES: $
run: |
for file in "$ALL_CHANGED_FILES"; do
echo "$file was changed"
done
tj-actions/changed-files (tj-actions/changed-files)
### [`v41.0.0`](https://togithub.com/tj-actions/changed-files/releases/tag/v41.0.0)
[Compare Source](https://togithub.com/tj-actions/changed-files/compare/v40.2.3...v41.0.0)
##### 🔥 🔥 BREAKING CHANGE 🔥 🔥
A new `safe_output` input is now available to prevent outputting unsafe filename characters (Enabled by default). This would escape characters in the filename that could be used for command injection.
> \[!NOTE]
> This can be disabled by setting the `safe_output` to false this comes with a recommendation to store all outputs generated in an environment variable first before using them.
##### Example
```yaml
...
- name: Get changed files
id: changed-files
uses: tj-actions/changed-files@v40
with:
safe_output: false # set to false because we are using an environment variable to store the output and avoid command injection.
- name: List all added files
env:
ADDED_FILES: ${{ steps.changed-files.outputs.added_files }}
run: |
for file in "$ADDED_FILES"; do
echo "$file was added"
done
...
```
##### What's Changed
- chore(deps): update typescript-eslint monorepo to v6.15.0 by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1801](https://togithub.com/tj-actions/changed-files/pull/1801)
- Upgraded to v40.2.3 by [@tj-actions-bot](https://togithub.com/tj-actions-bot) in [https://github.com/tj-actions/changed-files/pull/1800](https://togithub.com/tj-actions/changed-files/pull/1800)
- chore(deps): update dependency eslint-plugin-prettier to v5.1.0 by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1802](https://togithub.com/tj-actions/changed-files/pull/1802)
- chore(deps): lock file maintenance by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1803](https://togithub.com/tj-actions/changed-files/pull/1803)
- chore(deps): update dependency eslint-plugin-prettier to v5.1.1 by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1804](https://togithub.com/tj-actions/changed-files/pull/1804)
- fix: update safe output regex and the docs by [@tj-actions-bot](https://togithub.com/tj-actions-bot) in [https://github.com/tj-actions/changed-files/pull/1805](https://togithub.com/tj-actions/changed-files/pull/1805)
- Revert "chore(deps): update actions/download-artifact action to v4" by [@jackton1](https://togithub.com/jackton1) in [https://github.com/tj-actions/changed-files/pull/1806](https://togithub.com/tj-actions/changed-files/pull/1806)
- Update README.md by [@jackton1](https://togithub.com/jackton1) in [https://github.com/tj-actions/changed-files/pull/1808](https://togithub.com/tj-actions/changed-files/pull/1808)
- chore(deps): lock file maintenance by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1809](https://togithub.com/tj-actions/changed-files/pull/1809)
- Updated README.md by [@tj-actions-bot](https://togithub.com/tj-actions-bot) in [https://github.com/tj-actions/changed-files/pull/1810](https://togithub.com/tj-actions/changed-files/pull/1810)
**Full Changelog**: https://github.com/tj-actions/changed-files/compare/v40...v41.0.0
Configuration
📅 Schedule: Branch creation - "" (UTC), Automerge - At any time (no schedule defined).
🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.
â™» Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.
🔕 Ignore: Close this PR and you won't be reminded about this update again.
[ ] If you want to rebase/retry this PR, check this box
This PR has been generated by Mend Renovate. View repository job log here.
This PR contains the following updates:
v40.2.3
->v41.0.0
GitHub Vulnerability Alerts
CVE-2023-51664
Summary
The
tj-actions/changed-files
workflow allows for command injection in changed filenames, allowing an attacker to execute arbitrary code and potentially leak secrets.Details
The
changed-files
action returns a list of files changed in a commit or pull request which provides anescape_json
input enabled by default, only escapes"
for JSON values.This could potentially allow filenames that contain special characters such as
;
and ` (backtick) which can be used by an attacker to take over the GitHub Runner if the output value is used in a raw fashion (thus being directly replaced before execution) inside arun
block. By running custom commands an attacker may be able to steal secrets such asGITHUB_TOKEN
if triggered on other events thanpull_request
. For example onpush
.Proof of Concept
$(whoami).txt
which is a valid filename.List all changed files
step below.Example output:
Impact
This issue may lead to arbitrary command execution in the GitHub Runner.
Resolution
A new
safe_output
input would be enabled by default and return filename paths escaping special characters like ;, ` (backtick), $, (), etc for bash environments.A safe recommendation of using environment variables to store unsafe outputs.
Resources
Release Notes
tj-actions/changed-files (tj-actions/changed-files)
### [`v41.0.0`](https://togithub.com/tj-actions/changed-files/releases/tag/v41.0.0) [Compare Source](https://togithub.com/tj-actions/changed-files/compare/v40.2.3...v41.0.0) ##### 🔥 🔥 BREAKING CHANGE 🔥 🔥 A new `safe_output` input is now available to prevent outputting unsafe filename characters (Enabled by default). This would escape characters in the filename that could be used for command injection. > \[!NOTE] > This can be disabled by setting the `safe_output` to false this comes with a recommendation to store all outputs generated in an environment variable first before using them. ##### Example ```yaml ... - name: Get changed files id: changed-files uses: tj-actions/changed-files@v40 with: safe_output: false # set to false because we are using an environment variable to store the output and avoid command injection. - name: List all added files env: ADDED_FILES: ${{ steps.changed-files.outputs.added_files }} run: | for file in "$ADDED_FILES"; do echo "$file was added" done ... ``` ##### What's Changed - chore(deps): update typescript-eslint monorepo to v6.15.0 by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1801](https://togithub.com/tj-actions/changed-files/pull/1801) - Upgraded to v40.2.3 by [@tj-actions-bot](https://togithub.com/tj-actions-bot) in [https://github.com/tj-actions/changed-files/pull/1800](https://togithub.com/tj-actions/changed-files/pull/1800) - chore(deps): update dependency eslint-plugin-prettier to v5.1.0 by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1802](https://togithub.com/tj-actions/changed-files/pull/1802) - chore(deps): lock file maintenance by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1803](https://togithub.com/tj-actions/changed-files/pull/1803) - chore(deps): update dependency eslint-plugin-prettier to v5.1.1 by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1804](https://togithub.com/tj-actions/changed-files/pull/1804) - fix: update safe output regex and the docs by [@tj-actions-bot](https://togithub.com/tj-actions-bot) in [https://github.com/tj-actions/changed-files/pull/1805](https://togithub.com/tj-actions/changed-files/pull/1805) - Revert "chore(deps): update actions/download-artifact action to v4" by [@jackton1](https://togithub.com/jackton1) in [https://github.com/tj-actions/changed-files/pull/1806](https://togithub.com/tj-actions/changed-files/pull/1806) - Update README.md by [@jackton1](https://togithub.com/jackton1) in [https://github.com/tj-actions/changed-files/pull/1808](https://togithub.com/tj-actions/changed-files/pull/1808) - chore(deps): lock file maintenance by [@renovate](https://togithub.com/renovate) in [https://github.com/tj-actions/changed-files/pull/1809](https://togithub.com/tj-actions/changed-files/pull/1809) - Updated README.md by [@tj-actions-bot](https://togithub.com/tj-actions-bot) in [https://github.com/tj-actions/changed-files/pull/1810](https://togithub.com/tj-actions/changed-files/pull/1810) **Full Changelog**: https://github.com/tj-actions/changed-files/compare/v40...v41.0.0Configuration
📅 Schedule: Branch creation - "" (UTC), Automerge - At any time (no schedule defined).
🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.
â™» Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.
🔕 Ignore: Close this PR and you won't be reminded about this update again.
This PR has been generated by Mend Renovate. View repository job log here.