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Introduction:
The modern software development lifecycle relies heavily on automated CI/CD pipelines, creating a high-value target for sophisticated adversaries. The recent supply chain attack attributed to TeamPCP, which expanded from a Trivy breach to target Checkmarx GitHub Actions, demonstrates a critical evolution in how attackers leverage stolen CI credentials to propagate compromises across an organization’s entire repository ecosystem. This attack highlights a dangerous shift where initial access is no longer the final goal but a stepping stone to inject malicious code directly into trusted build workflows, effectively weaponizing the very automation designed to secure software.
Learning Objectives:
- Understand the mechanics of a cascading CI/CD supply chain attack and how stolen tokens are reused for lateral movement.
- Learn to audit GitHub Actions workflows for exposed secrets and insecure practices that facilitate credential theft.
- Implement proactive detection and mitigation strategies to harden CI pipelines against similar credential-stealing attacks.
You Should Know:
- Dissecting the TeamPCP Attack Vector: From Trivy to Checkmarx
The core of this attack lies in the exploitation of CI/CD trust relationships. In the initial Trivy breach, attackers successfully exfiltrated CI credentials—specifically GitHub Personal Access Tokens (PATs) or workflow secrets—from the compromised environment. TeamPCP then expanded this attack to Checkmarx GitHub Actions by reusing these stolen tokens. The modus operandi is a classic “island hopping” maneuver: once a token with sufficient scope (typically `repo` and `workflow` permissions) is stolen, attackers can push malicious commits to any repository the token has access to.
This is not a vulnerability within Checkmarx’s code itself but a compromise of the token’s integrity. The attack simulates a trusted developer, executing commands like `git push` to inject malicious code or alter workflow YAML files. This creates a cascading effect where each newly compromised repository becomes a new launchpad, exfiltrating its own set of secrets and perpetuating the attack chain.
To understand this from a defensive perspective, we can simulate the audit log analysis for such an event. On a Linux system, you can use the GitHub CLI (gh) to audit recent workflow runs for unexpected actors:
List recent workflow runs for a repository to spot anomalies gh run list --repo owner/repo --limit 10 Examine the specific job logs for credential access attempts gh run view <run-id> --repo owner/repo --log To check for unexpected pushes, use the GitHub API via curl curl -H "Authorization: token $GITHUB_TOKEN" \ https://api.github.com/repos/owner/repo/commits?author=unexpected-user
On Windows, PowerShell can be used with the `Invoke-RestMethod` cmdlet to query the same API, focusing on `commits` and `workflow_runs` endpoints to identify unusual activity patterns, such as commits from external actors or workflows running with altered YAML.
2. Hardening CI/CD Against Stolen Token Reuse
Preventing the reuse of stolen tokens requires a shift from static secrets to ephemeral, scoped credentials. The attack succeeded because a compromised token was valid and reusable. To mitigate this, organizations must implement OIDC (OpenID Connect) for cloud deployments and use GitHub’s fine-grained personal access tokens (PATs) with the principle of least privilege.
The following step-by-step guide demonstrates how to replace a long-lived repository secret with OIDC for AWS deployment in a GitHub Actions workflow, drastically reducing the blast radius of a token leak.
Step 1: Configure the Cloud Provider (AWS)
Create an OIDC identity provider in AWS IAM. This links your GitHub repository to AWS without storing a static key.
Linux/macOS CLI using aws cli to create an OIDC provider aws iam create-open-id-connect-provider \ --url https://token.actions.githubusercontent.com \ --client-id-list sts.amazonaws.com \ --thumbprint-list "6938fd4d98bab03faadb97b34396831e3780aea1"
Note: On Windows, this can be executed via AWS CLI in PowerShell with the same syntax.
Step 2: Create an IAM Role for GitHub Actions
Define a trust policy that allows the specific GitHub repository to assume the role.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Federated": "arn:aws:iam::ACCOUNT-ID:oidc-provider/token.actions.githubusercontent.com"
},
"Action": "sts:AssumeRoleWithWebIdentity",
"Condition": {
"StringEquals": {
"token.actions.githubusercontent.com:aud": "sts.amazonaws.com",
"token.actions.githubusercontent.com:sub": "repo:owner/repo:ref:refs/heads/main"
}
}
}
]
}
Step 3: Update GitHub Actions Workflow
Modify your workflow YAML to use the OIDC role instead of a stored secret.
jobs: deploy: permissions: id-token: write This is mandatory for OIDC contents: read steps: - name: Configure AWS Credentials uses: aws-actions/configure-aws-credentials@v2 with: role-to-assume: arn:aws:iam::ACCOUNT-ID:role/GitHubActionsRole aws-region: us-east-1
3. Detecting Malicious Commits in CI Workflows
Beyond prevention, continuous detection is vital. The TeamPCP attack involved pushing malicious commits. Defenders must monitor for unauthorized or anomalous changes to workflow files (.github/workflows/.yml). A robust detection strategy involves using tools like `truffleHog` or `Gitleaks` not just for secrets, but for scanning the commit history of CI configurations for indicators of compromise (IoCs).
To scan a repository for leaked secrets or suspicious patterns post-breach, use truffleHog:
Linux/macOS trufflehog filesystem --directory /path/to/repo --json --only-verified To scan a specific branch for high-entropy strings that might be tokens trufflehog git https://github.com/owner/repo.git --branch main --entropy
On Windows, the same command runs via WSL or Windows binary. Additionally, configure GitHub’s code scanning alerts to flag when a workflow file is modified by a user who is not a designated repository admin. This can be automated using GitHub’s GraphQL API to query for `PullRequest` events that modify files under `.github/workflows/` and cross-reference the author with a safe-list.
4. Incident Response: Containing a Cascading CI Compromise
If a cascading compromise like TeamPCP’s is suspected, the response must prioritize revoking trust immediately. The following steps outline a containment strategy:
- Revoke and Rotate All Tokens: Immediately expire all GitHub PATs, OAuth tokens, and deploy keys associated with the impacted organization. On Linux, this can be automated via `gh api` to list and delete tokens.
- Disable Actions: Temporarily disable GitHub Actions at the organization level to halt the execution of malicious workflows. This is a critical break-glass procedure.
- Forensic Auditing: Download workflow logs before they expire (GitHub retains them for 90 days). Use `jq` (Linux/macOS) or PowerShell to parse JSON logs for `run` steps that executed unauthorized scripts.
- Revert Malicious Commits: Use `git revert` to undo unauthorized commits, ensuring the commit history remains intact for forensic analysis.
Example: Revoking a Token via GitHub CLI
List all tokens for a user (requires admin permissions) gh api users/<username>/authorizations --jq '.[].id' Revoke a specific token by ID gh api -X DELETE users/<username>/authorizations/<token-id>
What Undercode Say:
- CI/CD is the New Perimeter: Traditional network security is irrelevant when attackers compromise the automation layer. The TeamPCP breach underscores that CI/CD pipelines must be treated with the same zero-trust rigor as production environments.
- Ephemeral Credentials are Mandatory: Long-lived tokens are a single point of failure. The shift to OIDC and fine-grained, time-bound tokens is no longer a best practice but a baseline requirement to prevent the cascading reuse demonstrated in this attack.
- Visibility into Workflow Changes is Lacking: Many organizations monitor code commits but fail to specifically alert on changes to GitHub Actions YAML files. Attackers exploit this blind spot, treating CI configuration changes as “noise” rather than a critical security event.
- The analysis reveals that supply chain attacks are becoming polymorphic; initial compromise is just a means to generate more compromised endpoints. Defenders must implement automated detection for credential exfiltration attempts within build logs, such as monitoring for `curl` commands targeting external IPs or `grep` patterns hunting for `GITHUB_TOKEN` in
${{ secrets. }}.
Prediction:
The TeamPCP attack methodology will become a blueprint for future CI/CD compromises, leading to a surge in “pipeline jacking” incidents. This will force a market-wide adoption of “build-time security” tools that analyze workflow behavior at runtime, rather than just scanning code for vulnerabilities. Consequently, we will likely see GitHub and other CI/CD platforms introduce mandatory OIDC enrollment for enterprise organizations and implement AI-driven anomaly detection to automatically pause workflows exhibiting credential exfiltration behaviors, effectively shifting security left to the very core of the automation process.
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IT/Security Reporter URL:
Reported By: Hackermohitkumar Teampcp – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
