T03 · Remote Payload Retrieval and Execution
- Location
SKILL.md:240- Finding
Unverified Remote Bun Installer Execution
- Content
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Vulnerability Details
File Location:
SKILL.md:240-243
Vulnerability Type: Remote payload retrieval and execution
Risk Level: HighComplete Code Snippet:
bash # macOS/Linux curl -fsSL https://bun.sh/install | bash # Windows (PowerShell) iwr https://bun.sh/install -outfile "install.ps1"; ./install.ps1Technical Analysis
The installation instructions retrieve mutable scripts from
https://bun.sh/installand execute them without pinning an immutable version or verifying a checksum or digital signature. The Unix command pipes the response directly into Bash, while the Windows command downloads the response and immediately executes it with PowerShell.Although
bun.shis presented as Bun's official installation endpoint, its response is external to the audited package and can change after review. Consequently, the code ultimately executed is not represented by the reviewed project contents. A compromise of the endpoint, its distribution infrastructure, or the network trust path could substitute arbitrary commands.This behavior is not required for the stock screener itself. Installing the documented runtime is a legitimate prerequisite, but executing an unverified remote installer grants substantially broader capability than the minimum needed to explain that prerequisite.
Attack Path
- A user or automated agent follows the installation instructions in
SKILL.md. - The command requests a mutable script from
https://bun.sh/install. - The response is not checked against a pinned checksum or trusted signature.
- Bash or PowerShell executes the response with the invoking user's privileges.
- If the remote response has been maliciously replaced, it can execute arbitrary commands, read user-accessible files, install additional software, or modify the user's environment.
Impact Assessment
Successful exploitation provides arbitrary code execution with the privileges of the ...[truncated 484 chars]
- A user or automated agent follows the installation instructions in
- Remediation
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Remediation Suggestions
- Remove instructions that pipe network responses directly into a shell or immediately execute downloaded scripts.
- Prefer a trusted operating-system package manager or another installation channel that performs package integrity and provenance verification.
- If a standalone installer is necessary, pin an explicit Bun release and immutable artifact URL.
- Publish the expected cryptographic checksum or signature and require verification before execution.
- Download the installer to a local file, inspect or verify it, and only then execute it as a separate deliberate step.
- Explicitly instruct users not to run the installer with elevated privileges unless a documented installation step strictly requires them.
- Keep runtime installation separate from Skill execution so the stock screener runs only with ordinary user privileges.