T09 · Insecure Skill Coding Practices
- Location
makefile-generator.sh:4- Finding
Unconditional Overwrite of an Existing Makefile
- Content
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Vulnerability Details
File Location:
makefile-generator.sh, lines 4–19
Vulnerability Type: Unsafe destructive file overwrite
Risk Level: LowVulnerable Code
bash cat > Makefile << 'MK' .PHONY: install test build clean dev install: npm install test: npm test build: npm run build dev: npm run dev clean: rm -rf node_modules dist MKTechnical Analysis
The script writes generated content directly to
Makefileusing truncating shell redirection. If a file with that name already exists in the current working directory, its contents are silently and immediately destroyed. The script does not check for an existing file, request confirmation, create a backup, or perform an atomic replacement.Because the output path is relative, the affected file depends entirely on the directory from which the user invokes the script. This is an insecure coding practice that can cause local data loss, although it does not independently enable privilege escalation or execution with permissions beyond those already held by the invoking user.
Attack Path
- A user has an existing project containing a customized
Makefile. - The user invokes
makefile-generator.shfrom the project root, expecting generation behavior consistent with the documentation. - Shell redirection opens the existing
Makefilewith truncation before writing the static template. - The original build, test, deployment, or maintenance targets are irreversibly replaced unless they are recoverable through version control or a separate backup.
- Subsequent automation may fail or behave differently because it now uses the replacement Makefile.
Impact Assessment
The issue can destroy an existing
Makefileaccessible to the invoking account and disrupt local or CI build workflows. Lost content may include project-specific build, test, cleanup, or deployment procedures. The effect is limited to files writable by the current user; no additional privileges, r ...[truncated 61 chars]- A user has an existing project containing a customized
- Remediation
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Remediation Suggestions
- Check whether
Makefilealready exists and refuse to overwrite it by default. - Require an explicit
--forceoption before replacing an existing file. - Support an explicit output path rather than relying solely on the current working directory.
- Write generated content to a securely created temporary file in the destination directory, validate successful generation, and then rename it atomically.
- If forced replacement is requested, optionally preserve the original as a backup.
- Return a nonzero exit status with a clear message when generation cannot proceed safely.
Example guard:
bash output="Makefile" if [[ -e "$output" && "$force" != "true" ]]; then printf 'Error: %s already exists; use --force to overwrite it.\n' "$output" >&2 exit 1 fi- Check whether