T03 · Remote Payload Retrieval and Execution
Error
- Location
- references/cli-installation-guide.md:7
- Finding
- Unverified Remote Content Is Downloaded and Executed as a Shell Script## Vulnerability Details **File Location**: `references/cli-installation-guide.md`, lines 7-13 **Vulnerability Type**: Unverified remote payload retrieval and execution **Risk Level**: High **Vulnerable code:** ```bash # Linux/macOS — download first, then execute curl -sSL -o /tmp/hcloud-install.sh https://support.huaweicloud.com/qs-hcli/hcli_02_003.html bash /tmp/hcloud-install.sh # Or download from: # https://support.huaweicloud.com/qs-hcli/hcli_02_003.html ``` ### Technical Analysis The installation instructions download content from a mutable external URL and immediately execute the resulting file with Bash. No cryptographic signature, expected checksum, version pin, content-type validation, or manual inspection is required before execution. The referenced URL has an `.html` suffix and is presented as a Huawei Cloud documentation page rather than a versioned shell-script artifact. Consequently, the command may download HTML rather than a valid installer. More importantly, any content ultimately returned after redirects is treated as trusted shell code. HTTPS protects the connection in transit when its trust assumptions hold, but it does not establish that the retrieved content is an immutable, reviewed installer. The effective payload can change after this skill package has been audited. Compromise of the remote publishing infrastructure, an authorized but malicious upstream modification, or an unsafe redirect could therefore turn these instructions into arbitrary code execution. Use of the predictable shared path `/tmp/hcloud-install.sh` also creates an avoidable local file-handling weakness. Another local process may be able to interfere with the path between download and execution, depending on host permissions and timing. ### Attack Path 1. An attacker gains control over the content served by the external URL, its redirect destination, or the relevant upstream publishing infrastructure. 2. The attacker cause ...[truncated 1811 chars]
- Remediation
- ## Remediation Suggestions 1. Replace the documentation-page URL with Huawei Cloud's official, versioned installer package or release artifact. 2. Pin an explicit CLI version instead of retrieving mutable latest content. 3. Publish and verify a SHA-256 or stronger digest obtained through a separately trusted channel. Prefer verification of a vendor-provided digital signature. 4. Do not execute a downloaded file until its signature, checksum, expected file type, and source have been validated. 5. Use strict download options such as `curl --fail --show-error --location` so HTTP errors are not silently written and passed to Bash. 6. Use a securely created temporary directory rather than a predictable shared filename, and remove it after installation. 7. Avoid piping or immediately passing remote content to a shell. Provide a review step or use a trusted operating-system package manager where supported. 8. Run installation with the minimum necessary user privileges and explicitly warn users not to execute it from a privileged shell unless required and independently verified. 9. A hardened pattern should resemble: ```bash tmp_dir="$(mktemp -d)" trap 'rm -rf "$tmp_dir"' EXIT curl --fail --show-error --location \ --output "$tmp_dir/hcloud-installer" \ "https://official.example/versioned/hcloud-installer-VERSION" printf '%s %s\n' "PINNED_SHA256" "$tmp_dir/hcloud-installer" | sha256sum --check - # Execute only after signature or checksum verification. bash "$tmp_dir/hcloud-installer" ``` The placeholder URL and digest must be replaced with verified values from official Huawei Cloud release documentation.