T09 · Insecure Skill Coding Practices
- Location
scripts/script.sh:5- Finding
Locally Stored Signup Records Lack Explicit Access Restrictions
- Content
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Vulnerability Details
File Location:
scripts/script.sh, lines 5–8; the same unrestricted file-creation pattern is repeated for action logs, such as line 134
Vulnerability Type: Insecure permissions for potentially sensitive local data
Risk Level: Mediumbash DATA_DIR="${HOME}/.local/share/signup" mkdir -p "$DATA_DIR" _log() { echo "$(date '+%m-%d %H:%M') $1: $2" >> "$DATA_DIR/history.log"; }A representative action log is also created without an explicit mode:
bash echo "$ts|$input" >> "$DATA_DIR/run.log"Technical Analysis
The script creates its data directory and log files without setting a restrictive
umaskor explicitly applying access permissions. Consequently, the resulting permissions depend entirely on the invoking process's environment.With a permissive
umask, or a common022configuration, generated files can be readable by other local users. The directory may also permit traversal by those users. The records managed by a signup utility can contain names, email addresses, registration details, reports, configuration values, or other personal information.This weakness affects
history.logand the command-specific logs created through shell redirection. Generated export files would be subject to the same inherited permission behavior if the export implementation became reachable.Attack Path
- A legitimate user runs the Skill and supplies signup or registration information.
- The script creates
~/.local/share/signupusing permissions derived from the currentumask. - It writes the supplied values to action logs and
history.log, again relying on inherited default permissions. - On a multi-user system where those defaults permit group or world access, another local account locates the user's home data directory.
- That account traverses the signup directory and reads the generated records.
Exploitation requires local system access and filesys ...[truncated 597 chars]
- Remediation
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Remediation Suggestions
Establish restrictive permissions before creating any storage:
bash umask 077 DATA_DIR="${HOME}/.local/share/signup" mkdir -p -m 700 "$DATA_DIR" chmod 700 "$DATA_DIR"Ensure every generated data or export file is owned by the invoking user and has mode
600. Existing files should also be corrected safely:bash find "$DATA_DIR" -type f -exec chmod 600 {} +Before writing, verify that the data directory is owned by the current user and is not a symbolic link. Where feasible, open files using mechanisms that reject symbolic links and create them atomically with exclusive, restrictive permissions.
Document that signup inputs are persisted locally, advise users not to enter secrets unnecessarily, and add automated tests that execute the script under permissive
umaskvalues to confirm that directories remain mode700and files remain mode600.