9 | A tool that detects presence of a Responder in the network
10 |
11 |
12 |
13 |
14 | Identifies compromised machines before hackers run away with the loot (hashes)
15 |
16 |
17 |
18 |
19 | Respounder sends LLMNR name resolution requests for made-up hostnames that do not exist.
20 | In a normal non-adversarial network we do not expect such names to resolve.
21 | However, a responder, if present in the network, will resolve such queries
22 | and therefore will be forced to reveal itself.
23 |
24 | ## Download
25 |
26 | ### Latest Releases
27 | Respounder is available for 32/64 bit linux, OS X and Windows systems.
28 | Latest versions can be downloaded from the
29 | [Release](https://github.com/codeexpress/respounder/releases) tab above.
30 |
31 | ### Build from source
32 | This is a golang project with no dependencies. Assuming you have golang compiler installed,
33 | the following will build the binary from scratch
34 | ```
35 | $ git clone https://github.com/codeexpress/respounder
36 | $ cd respounder
37 | $ go build -o respounder respounder.go
38 | ```
39 |
40 | ## Usage
41 |
42 | Running `respounder` is as simple as invoking it on the command line.
43 | Example invocation:
44 | ```bash
45 | $ ./respounder
46 |
47 |
48 | .´/
49 | / ( .----------------.
50 | [ ]░░░░░░░░░░░|// RESPOUNDER //|
51 | ) ( '----------------'
52 | '-'
53 |
54 | [wlan0] Sending probe from 192.168.0.19... responder not detected
55 | [vmnet1] Sending probe from 172.16.211.1... responder not detected
56 | [vmnet8] Sending probe from 172.16.55.1... responder detected at 172.16.55.128
57 | ```
58 |
59 | ### Flags
60 |
61 | ```
62 | $ ./respounder [-json] [-debug] [-hostname testhostname | -rhostname]
63 |
64 | Flags:
65 | -json
66 | Prints a JSON to STDOUT if a responder is detected on
67 | the network. Other text is sent to STDERR
68 | -debug
69 | Creates a debug.log file with a trace of the program
70 | -interface string
71 | Interface where responder will be searched (eg. eth0).
72 | Not specifying this flag will search on all interfaces.
73 | -hostname string
74 | Hostname to search for (default "aweirdcomputername")
75 | -rhostname
76 | Searches for a hostname comprised of random string instead
77 | of the default hostname ("aweirdcomputername")
78 | ```
79 |
80 | ### Typical usage scenario
81 |
82 | #### Personal
83 | Detect rogue hosts running responder on public Wi-Fi networks
84 | e.g. like airports, cafés and avoid joining such networks
85 | (especially if you are running windows OS)
86 |
87 | #### Corporate
88 | Detect network compromises as soon as they happen by running respounder
89 | in a loop
90 |
91 | For eg. the following `crontab` runs respounder every minute and logs a JSON file to syslog
92 | whenever a responder is detected.
93 | ```bash
94 | * * * * * /path/to/respounder -json | /usr/bin/logger -t responder-detected
95 | ```
96 |
97 | Example `syslog` entry:
98 | ```bash
99 | code@express:~/$ sudo tail -f /var/log/syslog
100 | Feb 9 03:44:07 responder-detected: [{"interface":"vmnet8","responderIP":"172.16.55.128","sourceIP":"172.16.55.1"}]
101 | ```
102 |
103 | ## Demo
104 | 
105 |
106 | ## Coming Up Next: Android App
107 | There are plans to port this tool to an android app so that adversarial Wi-Fi networks
108 | (eg. WiFi Pineapple or WiFi Pumpkin running responder) can be
109 | detected right from a mobile phone.
110 |
--------------------------------------------------------------------------------
/respounder.go:
--------------------------------------------------------------------------------
1 | package main
2 |
3 | import (
4 | "crypto/sha1"
5 | "encoding/hex"
6 | "encoding/json"
7 | "flag"
8 | "fmt"
9 | "io/ioutil"
10 | "log"
11 | "math/rand"
12 | "net"
13 | "os"
14 | "strings"
15 | "time"
16 | )
17 |
18 | const (
19 | Banner = `
20 |
21 | .´/
22 | / ( .----------------.
23 | [ ]░░░░░░░░░░░|// RESPOUNDER //|
24 | ) ( '----------------'
25 | '-'
26 | `
27 |
28 | Version = 1.2
29 | TimeoutSec = 3
30 | BcastAddr = "224.0.0.252"
31 | LLMNRPort = 5355
32 | DefaultHostname = "aweirdcomputername"
33 | )
34 |
35 | const (
36 | def = 0x00
37 | newHostname = 0x01
38 | randHostname = 0x02
39 | )
40 |
41 | var (
42 | // stdout is default output
43 | outFile = os.Stdout
44 |
45 | // default logger is set to abyss
46 | logger = log.New(ioutil.Discard, "", 0)
47 |
48 | // argument flags
49 | jsonPtr = flag.Bool("json", false,
50 | `Prints a JSON to STDOUT if a responder is detected in the subnet.
51 | Other text is sent to STDERR`)
52 |
53 | debugPtr = flag.Bool("debug", false,
54 | `Creates a debug.log file with a trace of the program`)
55 |
56 | hostnamePtr = flag.String("hostname", DefaultHostname,
57 | `Hostname to search for`)
58 |
59 | randHostnamePtr = flag.Bool("rhostname", false,
60 | `Searches for a hostname comprised of random string instead
61 | of the default hostname ("`+DefaultHostname+`")`)
62 |
63 | interfacePtr = flag.String("interface", "",
64 | `Interface where responder will be searched (eg. eth0).
65 | Not specifying this flag will search on all interfaces.`)
66 |
67 | hostnameType byte
68 | )
69 |
70 | func init() {
71 | rand.Seed(time.Now().UnixNano())
72 | }
73 |
74 | func main() {
75 | initFlags()
76 | flag.Parse()
77 |
78 | if *hostnamePtr != DefaultHostname {
79 | hostnameType = newHostname
80 | } else if *randHostnamePtr {
81 | hostnameType = randHostname
82 | } else {
83 | hostnameType = def
84 | }
85 |
86 | fmt.Fprintln(os.Stderr, Banner)
87 |
88 | interfaces, _ := net.Interfaces()
89 | logger.Println("======== Starting RESPOUNDER ========")
90 | logger.Printf("List of all interfaces: \n %+v\n", interfaces)
91 |
92 | var resultMap []map[string]string
93 |
94 | // send probe on specific interface if -interface flag is set
95 | if *interfacePtr != "" {
96 | inf, err := net.InterfaceByName(*interfacePtr)
97 | if err != nil {
98 | fmt.Printf("Invalid interface '%s'. List of valid interfaces are:\n", *interfacePtr)
99 | for _, inf := range interfaces {
100 | fmt.Println("- " + inf.Name)
101 | }
102 | return
103 | }
104 | detailsMap := checkResponderOnInterface(*inf)
105 | if len(detailsMap) > 0 {
106 | resultMap = append(resultMap, detailsMap)
107 | }
108 | } else { // send probes from all interfaces if -interface flag isn't set
109 | for _, inf := range interfaces {
110 | detailsMap := checkResponderOnInterface(inf)
111 | if len(detailsMap) > 0 {
112 | resultMap = append(resultMap, detailsMap)
113 | }
114 | }
115 | }
116 |
117 | if *debugPtr {
118 | fmt.Fprintln(os.Stderr, "Debug file 'debug.log' created.")
119 | }
120 |
121 | if *jsonPtr {
122 | resultJSON, _ := json.Marshal(resultMap)
123 | fmt.Println(string(resultJSON))
124 | }
125 | logger.Println("======== Ending RESPOUNDER Session ========")
126 | }
127 |
128 | // Test presence of responder on a given interface
129 | func checkResponderOnInterface(inf net.Interface) map[string]string {
130 | var json map[string]string
131 | addrs, _ := inf.Addrs()
132 | logger.Printf("List of all addresses on interface [%s]: %+v\n",
133 | inf.Name, addrs)
134 | ip := getValidIPv4Addr(addrs)
135 | logger.Printf("Bind IP address for interface %+v is %+v\n",
136 | inf.Name, ip)
137 |
138 | if ip != nil {
139 | fmt.Fprintf(outFile, "%-10s Sending probe from %s...\t",
140 | "["+inf.Name+"]", ip)
141 | responderIP := sendLLMNRProbe(ip)
142 | if responderIP != "" {
143 | fmt.Fprintf(outFile, "responder detected at %s\n", responderIP)
144 | json = map[string]string{
145 | "interface": inf.Name,
146 | "sourceIP": ip.String(),
147 | "responderIP": responderIP,
148 | }
149 | } else {
150 | fmt.Fprintln(outFile, "responder not detected")
151 | }
152 | }
153 | return json
154 | }
155 |
156 | // Creates and sends a LLMNR request to the UDP multicast address.
157 | func sendLLMNRProbe(ip net.IP) string {
158 | var cName string
159 | responderIP := ""
160 | // 2 byte random transaction id eg. 0x8e53
161 | randomTransactionID := fmt.Sprintf("%04x", rand.Intn(65535))
162 |
163 | switch hostnameType {
164 | case def, newHostname:
165 | cName = string(*hostnamePtr)
166 | case randHostname:
167 | cName = randomHostname()
168 | }
169 |
170 | cNameLen := fmt.Sprintf("%02x", len(cName))
171 | encCName := hex.EncodeToString([]byte(cName))
172 | // LLMNR request in raw bytes
173 | llmnrRequest := randomTransactionID +
174 | "00000001000000000000" + cNameLen + encCName + "0000010001"
175 | n, _ := hex.DecodeString(llmnrRequest)
176 |
177 | remoteAddr := net.UDPAddr{IP: net.ParseIP(BcastAddr), Port: LLMNRPort}
178 |
179 | conn, err := net.ListenUDP("udp", &net.UDPAddr{IP: ip})
180 | if err != nil {
181 | fmt.Printf("Could not bind to the interface. Is it disabled? ")
182 | logger.Printf("Bind error: %+v\nSource IP: %v\n", err, ip)
183 | return responderIP // return with IP = ''
184 | }
185 |
186 | defer conn.Close()
187 | _, _ = conn.WriteToUDP(n, &remoteAddr)
188 |
189 | conn.SetReadDeadline(time.Now().Add(TimeoutSec * time.Second))
190 | buffer := make([]byte, 1024)
191 | bytes, clientIP, err := conn.ReadFromUDP(buffer)
192 | if err == nil { // no timeout (or any other) error
193 | responderIP = strings.Split(clientIP.String(), ":")[0]
194 | logger.Printf("LLMNR request payload was: %x\n", n)
195 | logger.Printf("Data received on %s from responder IP %s: %x\n",
196 | ip, clientIP, buffer[:bytes])
197 | } else {
198 | logger.Printf("Error getting response: %s\n", err)
199 | }
200 | return responderIP
201 | }
202 |
203 | // Calculate random hostname by taking random length
204 | // of the SHA1 of current time.
205 | func randomHostname() string {
206 | currentTime := time.Now().Format("2006-01-02 15:04:05")
207 | h := sha1.New()
208 | h.Write([]byte(currentTime))
209 | bs := h.Sum(nil)
210 | randomSlice := bs[:(rand.Intn(len(bs)-3) + 3)]
211 | randomName := fmt.Sprintf("%x\n", randomSlice)
212 | return randomName
213 | }
214 |
215 | // From all the IP addresses of this interface,
216 | // extract the IPv4 address where we'll bind to
217 | func getValidIPv4Addr(addrs []net.Addr) net.IP {
218 | var ip net.IP
219 | for _, addr := range addrs { // amongst all addrs,
220 | ip = addr.(*net.IPNet).IP.To4() // pick the IPv4 addr
221 | if ip != nil && ip.String() != "127.0.0.1" {
222 | break
223 | }
224 | }
225 | return ip
226 | }
227 |
228 | // parses cmd line flag and set appropriate variables
229 | func initFlags() {
230 | flag.Usage = func() {
231 | fmt.Fprintf(os.Stderr, "Respounder version %1.1f\n", Version)
232 | fmt.Fprintf(os.Stderr, "Usage: $ respounder [-json] [-debug] [-interface ] [-hostname | -rhostname]")
233 | fmt.Fprintf(os.Stderr, "\n\nFlags:\n")
234 | flag.PrintDefaults()
235 | }
236 |
237 | flag.Parse()
238 | if *jsonPtr {
239 | outFile = os.Stderr
240 | }
241 | if *debugPtr {
242 | f, err := os.OpenFile("debug.log",
243 | os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
244 | if err != nil {
245 | panic(err)
246 | }
247 | logger = log.New(f, "", 0)
248 | logger.SetPrefix("[" + time.Now().Format("02-Jan-2006 15:04:05 MST") + "]: ")
249 | }
250 | }
251 |
--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
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2 |
3 | # res·pound·er
4 | /rɪˈspaʊnd dər/
5 | noun
6 |