Additional critical fixes: malware-scanner.sh - input validation & error handling

ADDITIONAL ISSUES FIXED (7 major issues):

1. MISSING INPUT VALIDATION - Lines 2743, 2785
   - Domain input now validated with regex (prevents injection, special chars)
   - Custom path now validated for existence and readability
   - Rejects invalid domain formats before processing

2. MALDET AVAILABILITY CHECK - Line 3035
   - maldet_scan_submenu() now verifies maldet is installed before running
   - Prevents crashes when user selects maldet menu but scanner isn't installed
   - Shows helpful message directing user to installation

3. DIRECTORY CREATION ERROR HANDLING - Line 1283
   - mkdir now checks for success, returns error on failure
   - chmod also checked with error handling
   - Prevents silent failures when /opt not writable or disk full

4. SESSION DIRECTORY RACE CONDITION - Line 1273
   - Added $$  (process ID) and $RANDOM to session naming
   - Prevents collision when multiple users run simultaneously
   - Unique naming: malware-YYYYMMDD-HHMMSS-PID-RANDOM

5. CONTROL PANEL DETECTION VALIDATION - Line 2598
   - Added check to verify control panel not "unknown" after detection
   - Prevents scanning with wrong directory structure
   - Shows clear error message with remediation steps

6. ARRAY BOUNDS VALIDATION - Line 3347
   - Check available_scanners array not empty before displaying
   - Prevents crashes when no scanners installed
   - Shows helpful message to install scanners first

7. CUSTOM PATH READABILITY - Line 2793
   - Validates path is readable (not just existent)
   - Prevents scanning paths with permission errors

VALIDATION & TESTING:
✓ Syntax validation passed
✓ All input validation patterns tested
✓ Error handling branches verified
✓ Race condition fix verified (unique naming)

CODE QUALITY IMPROVEMENTS:
- Better error messages guide user to solutions
- Defensive programming prevents crashes
- Input sanitization prevents injection attacks
- Array bounds checked before access

modules/security/malware-scanner.sh

@@ -1269,8 +1269,8 @@ generate_standalone_scanner() {
         return 1
     fi
 
-    # Create session ID and directory
-    local session_id="malware-$(date +%Y%m%d-%H%M%S)"
+    # Create session ID and directory (with PID and random for collision avoidance)
+    local session_id="malware-$(date +%Y%m%d-%H%M%S)-$$-$RANDOM"
     local session_dir="/opt/${session_id}"
 
     echo ""
@@ -1279,8 +1279,19 @@ generate_standalone_scanner() {
     echo "Location: $session_dir"
     echo ""
 
-    # Create directory structure
-    mkdir -p "$session_dir"/{logs,results}
+    # Create directory structure with error checking
+    mkdir -p "$session_dir"/{logs,results} || {
+        echo -e "${RED}ERROR: Failed to create scan directory: $session_dir${NC}"
+        echo "Check that /opt is writable and has sufficient disk space"
+        read -p "Press Enter to continue..."
+        return 1
+    }
+
+    chmod 755 "$session_dir" || {
+        echo -e "${RED}ERROR: Failed to set permissions on $session_dir${NC}"
+        read -p "Press Enter to continue..."
+        return 1
+    }
 
     # Create standalone scan script
     cat > "$session_dir/scan.sh" << 'STANDALONE_EOF'
@@ -2585,6 +2596,25 @@ launch_standalone_scanner_menu() {
     echo ""
 
     if ! detect_control_panel; then
+        echo -e "${RED}ERROR: Control panel detection failed${NC}"
+        echo ""
+        echo "Cannot determine correct directory structure for scan."
+        echo "Your system may be using an unsupported control panel or"
+        echo "be configured as standalone."
+        echo ""
+        read -p "Press Enter to continue..."
+        return 1
+    fi
+
+    # Verify detection didn't just set to "unknown"
+    if [ "$CONTROL_PANEL" = "unknown" ]; then
+        echo -e "${RED}ERROR: Unable to detect control panel${NC}"
+        echo ""
+        echo "Cannot safely scan without knowing the directory structure."
+        echo "You can still:"
+        echo "  • Use custom path scanning option"
+        echo "  • Manually configure paths for your control panel"
+        echo ""
         read -p "Press Enter to continue..."
         return 1
     fi
@@ -2748,6 +2778,16 @@ launch_standalone_scanner_menu() {
                 return 1
             fi
 
+            # Validate domain format (prevent injection and invalid domains)
+            # Accepts: example.com, sub.example.com, etc.
+            # Rejects: special chars, spaces, wildcards, shell metacharacters
+            if [[ ! "$domain" =~ ^[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(\.[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$ ]]; then
+                echo -e "${RED}Invalid domain format${NC}"
+                echo "Domain must contain only letters, numbers, hyphens, and dots"
+                read -p "Press Enter to continue..."
+                return 1
+            fi
+
             # Find docroot for domain (FIXED: more specific matching with word boundaries)
             # Escape domain for use in regex (handle dots, hyphens, etc.)
             local domain_escaped=$(printf '%s\n' "$domain" | sed 's/[.]/\\./g' | sed 's/-/\\-/g')
@@ -2786,6 +2826,13 @@ launch_standalone_scanner_menu() {
                 return 1
             fi
 
+            # Verify path is readable
+            if [ ! -r "$custom_path" ]; then
+                echo -e "${RED}Path is not readable (permission denied): $custom_path${NC}"
+                read -p "Press Enter to continue..."
+                return 1
+            fi
+
             scan_paths=("$custom_path")
             scan_description="custom path $custom_path"
             ;;
@@ -3016,6 +3063,18 @@ delete_standalone_sessions() {
 # Main scan menu
 # Maldet-specific scan menu (dedicated section for fastest scanner)
 maldet_scan_submenu() {
+    # Verify Maldet is installed before proceeding
+    if ! is_scanner_cached "maldet"; then
+        echo ""
+        echo -e "${RED}ERROR: Maldet is not installed${NC}"
+        echo ""
+        echo "To install Maldet, use option 10 from the main menu:"
+        echo "  Main Menu → Install Maldet (fast, Linux-specific)"
+        echo ""
+        read -p "Press Enter to return to main menu..."
+        return 1
+    fi
+
     while true; do
         echo ""
         print_header "Maldet Scanner - Linux Malware Detection"
@@ -3284,6 +3343,15 @@ view_scan_results() {
         1)
             # Toolkit scan results
             echo ""
+
+            # Check if any scanners are available
+            if [ ${#available_scanners[@]} -eq 0 ]; then
+                echo -e "${YELLOW}No scanners are currently installed${NC}"
+                echo "Use option 13 from main menu to install scanners"
+                read -p "Press Enter to continue..."
+                return 1
+            fi
+
             echo "Select scanner to view results:"
             local i=1
             for scanner in "${available_scanners[@]}"; do