T08 · Insecure Dependencies
Error
- Location
- SKILL.md:43
- Finding
- Unverified Mutable Binary Installed into a Trusted System Path## Vulnerability Details **File Location**: `SKILL.md`, lines 43–48 **Vulnerability Type**: Unverified third-party binary installation **Risk Level**: High ### Vulnerable Code ```bash WSL/Linux generic binary install: ```bash curl -fsSL https://github.com/cloudflare/cloudflared/releases/latest/download/cloudflared-linux-amd64 -o /usr/local/bin/cloudflared sudo chmod +x /usr/local/bin/cloudflared ``` ``` ### Technical Analysis The installation procedure retrieves the `cloudflared` executable from a mutable `latest` release URL and places it directly into the trusted system executable directory `/usr/local/bin`. It does not pin an explicit version or validate the downloaded artifact using a cryptographic checksum or signature. HTTPS authenticates the transport endpoint but does not independently establish the integrity and provenance of the delivered executable. The effective payload may change after the Skill has been reviewed whenever the upstream `latest` release changes. Compromise of the upstream release process, repository account, release artifact, or delivery infrastructure could consequently substitute a malicious executable. The instructions then make the downloaded file executable. Later operations described by the Skill invoke `cloudflared`, causing the substituted payload to execute. Writing directly to `/usr/local/bin` also risks leaving an incomplete or corrupted executable if the transfer is interrupted. On systems where that directory is not writable by the current user, the download command will fail; the dangerous installation path applies when the command is run with sufficient permissions or the directory is otherwise writable. ### Attack Path 1. An attacker compromises or influences the upstream release artifact, associated release account, redirect destination, or delivery path. 2. The mutable `latest` URL begins serving an attacker-controlled `cloudflared-linux-amd64` payload. 3. A user or agen ...[truncated 1223 chars]
- Remediation
- ## Remediation Suggestions 1. Pin `cloudflared` to an explicitly reviewed version instead of using the mutable `latest` URL. 2. Download the executable and its official checksum or signature into a newly created temporary directory. 3. Verify the artifact with a cryptographically authenticated checksum or vendor signing key before making it executable. 4. Abort installation on any download, signature, checksum, ownership, or permission failure. 5. Install only the verified temporary artifact using a privileged, atomic operation such as `sudo install`, rather than downloading directly into `/usr/local/bin`. 6. Ensure the destination is owned by `root` and is not writable by unprivileged users. 7. Prefer Cloudflare's authenticated platform package repository where available, while retaining explicit version controls where reproducible installation is required. 8. Re-run `cloudflared --version` after installation and verify that the reported version exactly matches the pinned version. Example hardened flow: ```bash set -euo pipefail version='PINNED_REVIEWED_VERSION' tmp_dir="$(mktemp -d)" trap 'rm -rf "$tmp_dir"' EXIT curl --fail --silent --show-error --location \ "https://github.com/cloudflare/cloudflared/releases/download/${version}/cloudflared-linux-amd64" \ --output "$tmp_dir/cloudflared" curl --fail --silent --show-error --location \ "https://github.com/cloudflare/cloudflared/releases/download/${version}/cloudflared-linux-amd64.sha256" \ --output "$tmp_dir/cloudflared.sha256" ( cd "$tmp_dir" sha256sum --check cloudflared.sha256 ) sudo install -o root -g root -m 0755 \ "$tmp_dir/cloudflared" /usr/local/bin/cloudflared cloudflared --version ``` The exact checksum filename and verification mechanism should follow the artifacts officially published for the pinned Cloudflare release. If vendor signatures are available, signature verification should be preferred or used in addition to chec ...[truncated 18 chars]