🛡️ Sentinel: [CRITICAL] Fix insecure temporary file usage in apt installer#55
🛡️ Sentinel: [CRITICAL] Fix insecure temporary file usage in apt installer#55
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…aller The `tools/os_installers/apt.sh` script previously downloaded the `yq` binary to a hardcoded, predictable path (`/tmp/yq`) before using `sudo` to move it. This exposes the system to symlink attacks or arbitrary file overwrite vulnerabilities by local attackers. This commit updates the script to securely generate a random temporary directory using `mktemp -d`. The `yq` binary is downloaded into this directory, moved securely, and the temporary directory is cleaned up afterward. A corresponding journal entry detailing this vulnerability and its prevention was also added to `.jules/sentinel.md`. Co-authored-by: kidchenko <5432753+kidchenko@users.noreply.github.com>
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📝 WalkthroughWalkthroughA security vulnerability in an installer script is documented through a new advisory file, and the apt.sh installer script is refactored to use secure temporary directory creation (mktemp -d) instead of hardcoding /tmp/yq, eliminating potential symlink attack vectors during privileged operations. Changes
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Actionable comments posted: 1
🧹 Nitpick comments (1)
tools/os_installers/apt.sh (1)
234-238: Consider adding trap-based cleanup for robustness.If
wgetorsudo mvfails, the script exits (due toset -eon line 7) before reaching line 238, leaving the temporary directory behind. While not a security issue, this can accumulate leaked temp directories over time.♻️ Proposed refactor using trap for cleanup
if ! command -v yq &> /dev/null; then YQ_VERSION="v4.44.6" tmp_dir=$(mktemp -d) + trap 'rm -rf "$tmp_dir"' EXIT wget "https://github.com/mikefarah/yq/releases/download/${YQ_VERSION}/yq_linux_amd64" -O "$tmp_dir/yq" sudo mv "$tmp_dir/yq" /usr/local/bin/yq sudo chmod +x /usr/local/bin/yq - rm -rf "$tmp_dir" + trap - EXIT + rm -rf "$tmp_dir" fiThe
trapensures cleanup happens even if the script exits early due to errors.🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@tools/os_installers/apt.sh` around lines 234 - 238, The tmp_dir created by mktemp can be left behind if wget or sudo mv fails; add a trap-based cleanup so the temp dir is removed on exit. After creating tmp_dir with tmp_dir=$(mktemp -d) (and before any failing commands like wget, sudo mv, chmod), install a trap that runs rm -rf "$tmp_dir" on EXIT (and optionally ERR), ensure the trap only runs when tmp_dir is non-empty, and if you need to keep the file on success, explicitly remove tmp_dir and/or remove the trap after successful install; reference tmp_dir, mktemp, wget, yq and the mv/chmod steps when making the change.
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Inline comments:
In @.jules/sentinel.md:
- Around line 1-4: Change the H2 heading "2024-05-15 - Insecure Temporary File
Creation in Installer Script" to a top-level H1 heading, add a blank line after
that heading, and reflow the following description lines (the vulnerability,
learning, and prevention bullets) to wrap at or below 80 characters so no lines
exceed the lint limit; ensure bullet markers and paragraph breaks are preserved
while keeping the same content.
---
Nitpick comments:
In `@tools/os_installers/apt.sh`:
- Around line 234-238: The tmp_dir created by mktemp can be left behind if wget
or sudo mv fails; add a trap-based cleanup so the temp dir is removed on exit.
After creating tmp_dir with tmp_dir=$(mktemp -d) (and before any failing
commands like wget, sudo mv, chmod), install a trap that runs rm -rf "$tmp_dir"
on EXIT (and optionally ERR), ensure the trap only runs when tmp_dir is
non-empty, and if you need to keep the file on success, explicitly remove
tmp_dir and/or remove the trap after successful install; reference tmp_dir,
mktemp, wget, yq and the mv/chmod steps when making the change.
ℹ️ Review info
⚙️ Run configuration
Configuration used: defaults
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Run ID: 2d47d2f6-7d47-41ad-afea-96055e3758f8
📒 Files selected for processing (2)
.jules/sentinel.mdtools/os_installers/apt.sh
| ## 2024-05-15 - Insecure Temporary File Creation in Installer Script | ||
| **Vulnerability:** Hardcoded temporary file path `/tmp/yq` used before a `sudo mv` operation, which can lead to symlink attacks or arbitrary code execution by local attackers. | ||
| **Learning:** Hardcoding paths in world-writable directories like `/tmp` is dangerous, especially in scripts that escalate privileges (`sudo`). An attacker can exploit this predictable path before the script has a chance to secure it. | ||
| **Prevention:** Always use securely generated random directories (e.g., `mktemp -d`) for temporary files, especially in privileged operations. |
There was a problem hiding this comment.
Address markdown linting violations.
The documentation linter is failing with multiple issues:
- Line 1: First line should be a top-level heading (H1
#) instead of H2 (##) - Line 1: Missing blank line after heading
- Lines 2-4: Lines exceed 80 characters
📝 Proposed fix for linting issues
-## 2024-05-15 - Insecure Temporary File Creation in Installer Script
-**Vulnerability:** Hardcoded temporary file path `/tmp/yq` used before a `sudo mv` operation, which can lead to symlink attacks or arbitrary code execution by local attackers.
-**Learning:** Hardcoding paths in world-writable directories like `/tmp` is dangerous, especially in scripts that escalate privileges (`sudo`). An attacker can exploit this predictable path before the script has a chance to secure it.
-**Prevention:** Always use securely generated random directories (e.g., `mktemp -d`) for temporary files, especially in privileged operations.
+# Sentinel Security Journal
+
+## 2024-05-15 - Insecure Temporary File Creation in Installer Script
+
+**Vulnerability:** Hardcoded temporary file path `/tmp/yq` used before a
+`sudo mv` operation, which can lead to symlink attacks or arbitrary code
+execution by local attackers.
+
+**Learning:** Hardcoding paths in world-writable directories like `/tmp` is
+dangerous, especially in scripts that escalate privileges (`sudo`). An
+attacker can exploit this predictable path before the script has a chance to
+secure it.
+
+**Prevention:** Always use securely generated random directories (e.g.,
+`mktemp -d`) for temporary files, especially in privileged operations.This adds a top-level heading, blank lines around headings, and wraps long lines to meet the 80-character limit.
📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| ## 2024-05-15 - Insecure Temporary File Creation in Installer Script | |
| **Vulnerability:** Hardcoded temporary file path `/tmp/yq` used before a `sudo mv` operation, which can lead to symlink attacks or arbitrary code execution by local attackers. | |
| **Learning:** Hardcoding paths in world-writable directories like `/tmp` is dangerous, especially in scripts that escalate privileges (`sudo`). An attacker can exploit this predictable path before the script has a chance to secure it. | |
| **Prevention:** Always use securely generated random directories (e.g., `mktemp -d`) for temporary files, especially in privileged operations. | |
| # Sentinel Security Journal | |
| ## 2024-05-15 - Insecure Temporary File Creation in Installer Script | |
| **Vulnerability:** Hardcoded temporary file path `/tmp/yq` used before a | |
| `sudo mv` operation, which can lead to symlink attacks or arbitrary code | |
| execution by local attackers. | |
| **Learning:** Hardcoding paths in world-writable directories like `/tmp` is | |
| dangerous, especially in scripts that escalate privileges (`sudo`). An | |
| attacker can exploit this predictable path before the script has a chance to | |
| secure it. | |
| **Prevention:** Always use securely generated random directories (e.g., | |
| `mktemp -d`) for temporary files, especially in privileged operations. |
🧰 Tools
🪛 GitHub Check: Lint Documentation
[failure] 4-4: Line length
.jules/sentinel.md:4:81 MD013/line-length Line length [Expected: 80; Actual: 142] https://github.com/DavidAnson/markdownlint/blob/v0.34.0/doc/md013.md
[failure] 3-3: Line length
.jules/sentinel.md:3:81 MD013/line-length Line length [Expected: 80; Actual: 234] https://github.com/DavidAnson/markdownlint/blob/v0.34.0/doc/md013.md
[failure] 2-2: Line length
.jules/sentinel.md:2:81 MD013/line-length Line length [Expected: 80; Actual: 175] https://github.com/DavidAnson/markdownlint/blob/v0.34.0/doc/md013.md
[failure] 1-1: First line in a file should be a top-level heading
.jules/sentinel.md:1 MD041/first-line-heading/first-line-h1 First line in a file should be a top-level heading [Context: "## 2024-05-15 - Insecure Tempo..."] https://github.com/DavidAnson/markdownlint/blob/v0.34.0/doc/md041.md
[failure] 1-1: Headings should be surrounded by blank lines
.jules/sentinel.md:1 MD022/blanks-around-headings Headings should be surrounded by blank lines [Expected: 1; Actual: 0; Below] [Context: "## 2024-05-15 - Insecure Temporary File Creation in Installer Script"] https://github.com/DavidAnson/markdownlint/blob/v0.34.0/doc/md022.md
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In @.jules/sentinel.md around lines 1 - 4, Change the H2 heading "2024-05-15 -
Insecure Temporary File Creation in Installer Script" to a top-level H1 heading,
add a blank line after that heading, and reflow the following description lines
(the vulnerability, learning, and prevention bullets) to wrap at or below 80
characters so no lines exceed the lint limit; ensure bullet markers and
paragraph breaks are preserved while keeping the same content.
1 participant
The
tools/os_installers/apt.shscript previously downloaded theyqbinary to a hardcoded, predictable path (/tmp/yq) before usingsudoto move it. This exposes the system to symlink attacks or arbitrary file overwrite vulnerabilities by local attackers.This PR updates the script to securely generate a random temporary directory using
mktemp -d. Theyqbinary is downloaded into this directory, moved securely, and the temporary directory is cleaned up afterward.A corresponding journal entry detailing this vulnerability and its prevention was also added to
.jules/sentinel.md.PR created automatically by Jules for task 9798981713892148457 started by @kidchenko
Summary by CodeRabbit