T07 · Tool Hijacking and Spoofing
Error
- Location
- summarize.sh:10
- Finding
- Working-Directory Helper Script Hijacking## Vulnerability Details **File Location**: `summarize.sh`, line 10 **Vulnerability Type**: Untrusted helper-script resolution **Risk Level**: High **Vulnerable Code**: ```bash ./extract.sh "$RSS_FILE" ``` ### Technical Analysis The script invokes `extract.sh` relative to the process's current working directory rather than relative to the installed location of `summarize.sh`. This conflicts with the documented ability to run the skill from any path. Consequently, `./extract.sh` can resolve to an attacker-supplied executable in the directory from which the user launches the genuine `summarize.sh`. Quoting `"$RSS_FILE"` protects the RSS argument from shell word splitting but does not protect the helper executable's path. ### Attack Path 1. An attacker creates or controls a directory that the victim will use as the current working directory. 2. The attacker places an executable named `extract.sh` in that directory and embeds arbitrary shell commands in it. 3. The victim invokes the genuine `summarize.sh` by its absolute or relative path while remaining in the attacker-controlled directory. 4. The RSS file check succeeds for the supplied input or a local `news.rss`. 5. At line 10, `summarize.sh` executes the attacker's `./extract.sh` instead of the helper shipped with the skill. 6. The malicious commands run with the invoking user's privileges. ### Impact Assessment Successful exploitation provides arbitrary command execution under the account running the skill. The attacker can access, modify, or delete data available to that user; execute additional local programs; and perform network or persistence actions permitted by the user's privileges. The flaw does not independently elevate privileges beyond those already held by the invoking process, so its scope is limited by that account's permissions.
- Remediation
- ## Remediation Suggestions Resolve the helper relative to the directory containing `summarize.sh`, not the current working directory: ```bash #!/usr/bin/env bash set -euo pipefail SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)" RSS_FILE="${1:-news.rss}" if [[ ! -f "$RSS_FILE" ]]; then printf 'RSS file not found: %s\n' "$RSS_FILE" >&2 exit 1 fi printf '%s\n' 'News highlights (first 10):' "$SCRIPT_DIR/extract.sh" "$RSS_FILE" ``` Additionally: - Ensure the packaged `extract.sh` is owned by a trusted account and is not writable by untrusted users. - Preserve argument quoting and use `--` with supporting utilities where appropriate. - Add a regression test that launches `summarize.sh` from a directory containing a decoy `extract.sh` and verifies that the packaged helper is used. - Consider validating that the resolved helper is a regular executable file before invoking it.