T09 · Insecure Skill Coding Practices
Warning
- Location
- scripts/generate_sop.sh:4
- Finding
- Path Traversal Allows File Creation or Overwrite Outside the SOP Output Directory## Vulnerability Details **File Location**: `scripts/generate_sop.sh`, lines 4-9 **Vulnerability Type**: Path traversal and unsafe file overwrite **Risk Level**: Medium ### Vulnerable Code ```bash TASK_NAME=$1 shift mkdir -p SOPs FILE="SOPs/${TASK_NAME// /_}.md" echo "# SOP: $TASK_NAME" > "$FILE" ``` ### Technical Analysis The script uses the first command-line argument to construct an output path. Its only sanitization replaces spaces with underscores; directory separators, `..` path components, and other filesystem-significant input remain unchanged. For example, a task name of `../README` produces the path: ```text SOPs/../README.md ``` This resolves to `README.md` outside the intended `SOPs/` directory. The `>` redirection creates the destination or truncates it if it already exists. The script also does not reject symbolic-link destinations, so filesystem links may redirect the write to another location. Quoting `"$FILE"` prevents shell word splitting and command substitution during path use, but it does not prevent path traversal because traversal is handled by filesystem path resolution. ### Attack Path 1. An attacker or untrusted caller controls the task-name argument supplied to `generate_sop.sh`. 2. The attacker supplies a traversal-bearing name, such as `../README`. 3. The script constructs `SOPs/../README.md`. 4. Filesystem path resolution places the destination outside `SOPs/`. 5. The redirection operator creates or truncates the destination file. 6. The script writes attacker-controlled task and workflow-step content into that file. Exploitation is limited to locations writable by the account executing the script and normally to filenames ending in `.md`. Existing symbolic links may expand the effective write target. ### Impact Assessment Successful exploitation allows creation or overwrite of writable Markdown files outside the documented output directory. This can corrupt pro ...[truncated 410 chars]
- Remediation
- ## Remediation Suggestions 1. Reject task names containing `/`, `\`, `..`, control characters, or an empty value. 2. Convert task names to a strict filename slug using an allowlist such as `[A-Za-z0-9_-]`. 3. Resolve the output directory and destination parent to canonical paths, then verify that the destination remains beneath the canonical `SOPs/` directory. 4. Refuse symbolic-link destinations and consider checking each relevant path component. 5. Avoid silently truncating existing files. Use an exclusive creation mechanism or require explicit authorization before overwriting. 6. Return a nonzero status when validation or safe file creation fails. Example validation approach: ```bash set -euo pipefail TASK_NAME=${1-} [[ -n "$TASK_NAME" ]] || { printf 'Error: task name is required\n' >&2 exit 1 } [[ "$TASK_NAME" != *"/"* && "$TASK_NAME" != *"\\"* && "$TASK_NAME" != *".."* ]] || { printf 'Error: invalid task name\n' >&2 exit 1 } SAFE_NAME=$(printf '%s' "$TASK_NAME" | sed 's/[^A-Za-z0-9_-]/_/g') mkdir -p -- SOPs FILE="SOPs/${SAFE_NAME}.md" [[ ! -e "$FILE" && ! -L "$FILE" ]] || { printf 'Error: destination already exists\n' >&2 exit 1 } ```