CRC32 brute force for dridex network requests

main.go

package main

import (
	"fmt"
	"hash/crc32"
)

const (
	MAXCHARLEN = 6
)

var (
	crcTable     *crc32.Table    = crc32.MakeTable(crc32.IEEE)
	seenCommands map[uint32]bool = map[uint32]bool{
		0x011f0411: true, // bot
		0x44c8f818: true, // list
		0xee7cbe69: true, // dmod6
		0x7775efd3: true, // dmod5
		0xf81ddc32: true, // dmod11
	}
)

func generateCombinations(alphabet string, length int) <-chan string {
	c := make(chan string)

	go func(c chan string) {
		defer close(c)

		addLetter(c, "", alphabet, length) // start with empty string
	}(c)

	return c // return chan
}

func addLetter(c chan string, combo string, alphabet string, length int) {
	if length <= 0 {
		return
	}

	var newCombo string
	for _, ch := range alphabet {
		newCombo = combo + string(ch)
		c <- newCombo
		addLetter(c, newCombo, alphabet, length-1)
	}
}

func hashFuncCrc32(val []byte) uint32 {
	return crc32.Checksum(val, crcTable)
}

func main() {
	for combination := range generateCombinations("abcdefghijklmnopqrstuvwxyz0123456789", MAXCHARLEN) {
		crc := hashFuncCrc32([]byte(combination))
		if seenCommands[crc] {
			fmt.Printf("found matching hash: %s = 0x%x\n", combination, crc)
		}
	}
}