Add strings command

cmd/strings.go

@@ -0,0 +1,81 @@
+/*
+Copyright © 2024 Alessandro Riva
+
+Licensed under the MIT License.
+See the LICENSE file for details.
+*/
+package cmd
+
+import (
+	"bufio"
+	"fmt"
+	"github.com/fatih/color"
+	"github.com/spf13/cobra"
+	"log"
+	"os"
+	"unicode"
+)
+
+var minLength int
+var asciiOnly bool
+
+var stringsCmd = &cobra.Command{
+	Use:   "strings [file]",
+	Short: "Extract printable strings from a file",
+	Long:  `The strings command scans a binary or any file for printable sequences of characters. Useful for malware analysis or file inspection.`,
+	Args:  cobra.ExactArgs(1),
+	Run: func(cmd *cobra.Command, args []string) {
+		filePath := args[0]
+		extractStrings(filePath)
+	},
+}
+
+func init() {
+	stringsCmd.Flags().IntVarP(&minLength, "min-length", "m", 5, "Minimum length of strings to extract (default is 5)")
+	stringsCmd.Flags().BoolVarP(&asciiOnly, "ascii", "a", false, "Extract only ASCII printable characters")
+	rootCmd.AddCommand(stringsCmd)
+}
+
+// extractStrings extracts printable strings from a file
+func extractStrings(filePath string) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		log.Fatalf("Could not open file: %v", err)
+	}
+	defer file.Close()
+
+	reader := bufio.NewReader(file)
+	var result []rune
+
+	color.Blue("Extracting strings from file: %s (Minimum length: %d)\n", filePath, minLength)
+
+	for {
+		char, _, err := reader.ReadRune()
+		if err != nil {
+			break
+		}
+
+		// Check if the character is printable
+		if isPrintable(char) {
+			result = append(result, char)
+		} else {
+			// If we encounter a non-printable character and result has enough characters, print the string
+			if len(result) >= minLength {
+				fmt.Println(string(result))
+			}
+			result = result[:0] // Reset result
+		}
+	}
+
+	// Print the remaining string if it's long enough
+	if len(result) >= minLength {
+		fmt.Println(string(result))
+	}
+}
+
+func isPrintable(char rune) bool {
+	if asciiOnly {
+		return char >= 32 && char <= 126 // ASCII printable characters
+	}
+	return unicode.IsPrint(char) // General Unicode printable characters
+}