Horizon Alert
Summary of the vulnerability and why it matters
This advisory concerns a critical vulnerability in Emissary, a workflow engine, that could allow an attacker with write access to inject malicious commands into build processes. This could lead to the compromise of code repositories and impact all systems that use them. The primary concern is confirming if Emissary is in use and if the affected versions are present in the environment.
- Workflow files allow malicious command injection.
- Affects code integrity and downstream users.
- Confirm Emissary relevance and exposure.
Attack Path
How an attacker could exploit the issue
An attacker with write access to a repository can compromise the supply chain by injecting malicious commands into GitHub Actions workflow files. This occurs when user-provided inputs are directly embedded into shell commands without proper sanitization, allowing the attacker to execute arbitrary code and poison the build process, affecting all users who depend on the poisoned software.
- Requires repository write access.
- User-controlled inputs in workflow files.
- Leads to code injection and supply chain compromise.
Live Threat
Current exploitation, exposure, and threat context
An attacker with repository write access could inject arbitrary shell commands into GitHub Actions workflow files. This may occur when user-controlled workflow dispatch inputs are interpolated directly into shell commands within these files, potentially leading to the compromise of all systems consuming these workflows.
- Repository code and build processes.
- Via interpolated user inputs in workflows.
- Supply chain compromise affecting downstream users.
Operational Fix
Recommended remediation, mitigation, and detection steps
Application owners responsible for Emissary, alongside platform and security teams, should lead the response to this critical vulnerability. The first step involves identifying all instances of Emissary within your environment, determining their exposure and business criticality, and locating the accountable owner for each instance. This will allow for a prioritized remediation plan, potentially involving vendor coordination if necessary.
- Application and Platform teams own the issue.
- Verify Emissary instances and exposure.
- Plan remediation based on risk assessment.
