T03 · Remote Payload Retrieval and Execution
- Location
SKILL.md:88- Finding
Unverified Remote Installation Script Executed Directly by Shell
- Content
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Vulnerability Details
File Location:
SKILL.md, line 88
Vulnerability Type: Remote payload retrieval and execution
Risk Level: HighVulnerable Code
bash curl -sL https://aka.ms/InstallAzureCliLinux | bashTechnical Analysis
The Linux installation instructions download a remote script from an
aka.msredirect and pipe its contents directly intobash. Althoughaka.msis associated with Microsoft and installing Azure CLI is relevant to the Skill's declared functionality, the command does not pin the retrieved artifact, disclose the final redirect destination, or verify a cryptographic checksum or signature before execution.The effective payload can therefore change after the Skill has been reviewed. The use of
-sLalso silently follows redirects, reducing visibility into the source and download process. If the redirect, final hosting location, delivery infrastructure, or remote script were compromised, an attacker could supply arbitrary shell commands. Those commands would execute immediately with the privileges of the user running the installation command.Direct execution of unverified remote content is not the minimum privilege or minimum-risk mechanism necessary to install Azure CLI. A signed operating-system package repository or a separately downloaded and verified installer would provide the required functionality with a narrower trust boundary.
Attack Path
- A user or AI Agent follows the Linux installation instructions in
SKILL.md. curlconnects to the shortened URL and silently follows its redirect.- The remote endpoint returns the current installer script. Its content is not pinned or locally inspected.
- The script is streamed directly to
bashwithout checksum or signature verification. - If the remote delivery path has been compromised, attacker-controlled shell commands execute immediately.
- Those commands can perform any action allowed to the invoking account and may obtain greater s ...[truncated 927 chars]
- A user or AI Agent follows the Linux installation instructions in
- Remediation
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Remediation Suggestions
- Replace the
curl | bashpipeline with Microsoft's documented signed package-repository installation procedure for the target Linux distribution. - Pin the Azure CLI package to an approved version where operationally feasible.
- Verify repository signing keys through an independently documented fingerprint and require package-signature validation.
- If a script-based installer is unavoidable:
- Use a documented final HTTPS URL instead of an opaque shortened redirect.
- Download the script to a local file without executing it.
- Verify a vendor-published cryptographic checksum or digital signature.
- Inspect the downloaded script before execution.
- Execute it as an unprivileged user unless a specific installation step demonstrably requires elevation.
- Apply elevated privileges only to the narrowly scoped commands that require them.
- Avoid silent download flags in security-sensitive installation documentation so users can observe failures and redirects.
- Document the expected source, version, hash, required privileges, and files or system settings modified by the installation process.
A safer conceptual workflow is:
bash curl --fail --show-error --location \ --output azure-cli-installer.sh \ "https://documented.vendor.example/pinned/installer.sh" echo "EXPECTED_SHA256 azure-cli-installer.sh" | sha256sum --check less azure-cli-installer.sh bash azure-cli-installer.shThe placeholder URL and checksum must be replaced with independently verified, vendor-published values. A signed distribution package remains preferable.
- Replace the