🛡️ Sentinel: [HIGH] Fix insecure temporary file handling#50
🛡️ Sentinel: [HIGH] Fix insecure temporary file handling#50
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…lers - Addressed a security concern in `tools/os_installers/apt.sh` where a downloaded binary was saved to a hardcoded predictable path in `/tmp/` before being moved with elevated privileges (`sudo`). - Replaced the hardcoded path with a securely generated directory using `mktemp -d` to prevent local privilege escalation and symlink attacks. - Documented the learning in `.jules/sentinel.md`. Co-authored-by: kidchenko <5432753+kidchenko@users.noreply.github.com>
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📝 WalkthroughWalkthroughA new security advisory documentation file is added, and an OS installer script is updated to use secure temporary directory creation instead of a hardcoded temporary path for the yq binary download and installation process. Changes
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Actionable comments posted: 2
🧹 Nitpick comments (1)
tools/os_installers/apt.sh (1)
234-238: Register anEXITtrap forYQ_TMP_DIRcleanup.This fixes the predictable temp path, but cleanup is still best-effort. With
set -e, any failure before Line 238 leaves the temp directory behind.Proposed change
YQ_VERSION="v4.44.6" YQ_TMP_DIR=$(mktemp -d) + trap 'rm -rf "$YQ_TMP_DIR"' EXIT wget "https://github.com/mikefarah/yq/releases/download/${YQ_VERSION}/yq_linux_amd64" -O "$YQ_TMP_DIR/yq" sudo mv "$YQ_TMP_DIR/yq" /usr/local/bin/yq sudo chmod +x /usr/local/bin/yq rm -rf "$YQ_TMP_DIR" + trap - EXIT🤖 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 temp directory created in the YQ installation block (YQ_TMP_DIR=$(mktemp -d)) can be left behind if the script exits early; add a trap to delete "$YQ_TMP_DIR" on EXIT so cleanup always runs. Specifically, after creating YQ_TMP_DIR, register a trap 'trap "rm -rf \"$YQ_TMP_DIR\"" EXIT' (or equivalent) and ensure the existing explicit rm -rf "$YQ_TMP_DIR" remains (the trap will be a no-op if already removed); reference YQ_TMP_DIR, mktemp, and the existing rm -rf line when applying 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:
- Line 1: The advisory heading currently reads "## 2025-03-06 - [Insecure
Temporary File Usage in OS Installer]" but should reflect the PR date; update
that heading to "## 2026-03-06 - [Insecure Temporary File Usage in OS
Installer]" so the record matches PR `#50`'s March 6, 2026 creation date; edit the
top-line heading string in .jules/sentinel.md to replace 2025-03-06 with
2026-03-06.
- Around line 1-4: The new entry titled "2025-03-06 - [Insecure Temporary File
Usage in OS Installer]" violates markdownlint rules MD041, MD022 and MD013; fix
it by ensuring the document has a single top-level heading (add an H1 before
this entry or change this heading to a lower-level heading consistent with the
file’s structure to satisfy MD041), ensure there is exactly one blank line after
the heading (MD022), and wrap long lines in the body to respect the repository
line-length policy (MD013) by breaking the long sentences (e.g., the
Vulnerability/Learning/Prevention lines) into shorter lines or paragraphs
without changing content meaning.
---
Nitpick comments:
In `@tools/os_installers/apt.sh`:
- Around line 234-238: The temp directory created in the YQ installation block
(YQ_TMP_DIR=$(mktemp -d)) can be left behind if the script exits early; add a
trap to delete "$YQ_TMP_DIR" on EXIT so cleanup always runs. Specifically, after
creating YQ_TMP_DIR, register a trap 'trap "rm -rf \"$YQ_TMP_DIR\"" EXIT' (or
equivalent) and ensure the existing explicit rm -rf "$YQ_TMP_DIR" remains (the
trap will be a no-op if already removed); reference YQ_TMP_DIR, mktemp, and the
existing rm -rf line when applying the change.
ℹ️ Review info
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Configuration used: defaults
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📒 Files selected for processing (2)
.jules/sentinel.mdtools/os_installers/apt.sh
| @@ -0,0 +1,4 @@ | |||
| ## 2025-03-06 - [Insecure Temporary File Usage in OS Installer] | |||
There was a problem hiding this comment.
Fix the advisory date in the heading.
Line 1 says 2025-03-06, but PR #50 was opened on March 6, 2026. If this heading is meant to record when the advisory was added, it is off by one year and will make the journal misleading.
🧰 Tools
🪛 GitHub Check: Lint Documentation
[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: "## 2025-03-06 - [Insecure Temp..."] 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: "## 2025-03-06 - [Insecure Temporary File Usage in OS Installer]"] 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 at line 1, The advisory heading currently reads "##
2025-03-06 - [Insecure Temporary File Usage in OS Installer]" but should reflect
the PR date; update that heading to "## 2026-03-06 - [Insecure Temporary File
Usage in OS Installer]" so the record matches PR `#50`'s March 6, 2026 creation
date; edit the top-line heading string in .jules/sentinel.md to replace
2025-03-06 with 2026-03-06.
| ## 2025-03-06 - [Insecure Temporary File Usage in OS Installer] | ||
| **Vulnerability:** A script (`tools/os_installers/apt.sh`) was hardcoding the temporary download path for a binary (`/tmp/yq`) before moving it to its final destination using `sudo mv`. | ||
| **Learning:** Hardcoding paths in shared temporary directories like `/tmp` creates a Time-of-Check to Time-of-Use (TOCTOU) race condition and enables symlink attacks. An attacker could pre-create a symlink at `/tmp/yq` pointing to a sensitive file, causing it to be overwritten or modified when the script executes with elevated privileges (`sudo`). | ||
| **Prevention:** Use `mktemp -d` to securely generate a unique temporary directory for downloads or intermediate files, rather than relying on predictable paths, especially before executing commands with elevated privileges. |
There was a problem hiding this comment.
Make the new entry markdownlint-clean.
This block currently trips MD041, MD022, and MD013, so ./build.sh lint will stay red until the heading level and line wrapping are fixed.
Proposed change
-## 2025-03-06 - [Insecure Temporary File Usage in OS Installer]
-**Vulnerability:** A script (`tools/os_installers/apt.sh`) was hardcoding the temporary download path for a binary (`/tmp/yq`) before moving it to its final destination using `sudo mv`.
-**Learning:** Hardcoding paths in shared temporary directories like `/tmp` creates a Time-of-Check to Time-of-Use (TOCTOU) race condition and enables symlink attacks. An attacker could pre-create a symlink at `/tmp/yq` pointing to a sensitive file, causing it to be overwritten or modified when the script executes with elevated privileges (`sudo`).
-**Prevention:** Use `mktemp -d` to securely generate a unique temporary directory for downloads or intermediate files, rather than relying on predictable paths, especially before executing commands with elevated privileges.
+# 2026-03-06 - Insecure Temporary File Usage in OS Installer
+
+**Vulnerability:** A script (`tools/os_installers/apt.sh`) hardcoded the
+temporary download path for a binary (`/tmp/yq`) before moving it to its final
+destination with `sudo mv`.
+
+**Learning:** Hardcoding paths in shared temporary directories like `/tmp`
+creates a Time-of-Check to Time-of-Use (TOCTOU) race condition and enables
+symlink attacks. An attacker could pre-create a symlink at `/tmp/yq` pointing
+to a sensitive file, causing it to be overwritten or modified when the script
+executes with elevated privileges (`sudo`).
+
+**Prevention:** Use `mktemp -d` to securely generate a unique temporary
+directory for downloads or intermediate files rather than relying on
+predictable paths, especially before executing commands with elevated
+privileges.📝 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.
| ## 2025-03-06 - [Insecure Temporary File Usage in OS Installer] | |
| **Vulnerability:** A script (`tools/os_installers/apt.sh`) was hardcoding the temporary download path for a binary (`/tmp/yq`) before moving it to its final destination using `sudo mv`. | |
| **Learning:** Hardcoding paths in shared temporary directories like `/tmp` creates a Time-of-Check to Time-of-Use (TOCTOU) race condition and enables symlink attacks. An attacker could pre-create a symlink at `/tmp/yq` pointing to a sensitive file, causing it to be overwritten or modified when the script executes with elevated privileges (`sudo`). | |
| **Prevention:** Use `mktemp -d` to securely generate a unique temporary directory for downloads or intermediate files, rather than relying on predictable paths, especially before executing commands with elevated privileges. | |
| # 2026-03-06 - Insecure Temporary File Usage in OS Installer | |
| **Vulnerability:** A script (`tools/os_installers/apt.sh`) hardcoded the | |
| temporary download path for a binary (`/tmp/yq`) before moving it to its final | |
| destination with `sudo mv`. | |
| **Learning:** Hardcoding paths in shared temporary directories like `/tmp` | |
| creates a Time-of-Check to Time-of-Use (TOCTOU) race condition and enables | |
| symlink attacks. An attacker could pre-create a symlink at `/tmp/yq` pointing | |
| to a sensitive file, causing it to be overwritten or modified when the script | |
| executes with elevated privileges (`sudo`). | |
| **Prevention:** Use `mktemp -d` to securely generate a unique temporary | |
| directory for downloads or intermediate files rather than relying on | |
| predictable paths, especially before executing commands with elevated | |
| privileges. |
🧰 Tools
🪛 GitHub Check: Lint Documentation
[failure] 4-4: Line length
.jules/sentinel.md:4:81 MD013/line-length Line length [Expected: 80; Actual: 223] 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: 349] 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: 185] 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: "## 2025-03-06 - [Insecure Temp..."] 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: "## 2025-03-06 - [Insecure Temporary File Usage in OS Installer]"] 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, The new entry titled "2025-03-06 -
[Insecure Temporary File Usage in OS Installer]" violates markdownlint rules
MD041, MD022 and MD013; fix it by ensuring the document has a single top-level
heading (add an H1 before this entry or change this heading to a lower-level
heading consistent with the file’s structure to satisfy MD041), ensure there is
exactly one blank line after the heading (MD022), and wrap long lines in the
body to respect the repository line-length policy (MD013) by breaking the long
sentences (e.g., the Vulnerability/Learning/Prevention lines) into shorter lines
or paragraphs without changing content meaning.
1 participant
🚨 Severity: HIGH
💡 Vulnerability: A script (
tools/os_installers/apt.sh) was hardcoding the temporary download path for a binary (/tmp/yq) before moving it to its final destination usingsudo mv.🎯 Impact: Hardcoding paths in shared temporary directories like
/tmpcreates a Time-of-Check to Time-of-Use (TOCTOU) race condition and enables symlink attacks. An attacker could pre-create a symlink at/tmp/yqpointing to a sensitive file, causing it to be overwritten or modified when the script executes with elevated privileges (sudo).🔧 Fix: Replaced the hardcoded path with a securely generated directory using
mktemp -dto handle downloads before moving them withsudo. Documented the learning in.jules/sentinel.md.✅ Verification: Run
./build.sh lintto verify thattools/os_installers/apt.shpasses linting and syntax checks successfully. Read.jules/sentinel.mdto confirm the journal entry.PR created automatically by Jules for task 5261296992179502194 started by @kidchenko
Summary by CodeRabbit
Documentation
Bug Fixes