├── .gitignore ├── LICENSE ├── Makefile ├── README.md └── respounder.go /.gitignore: -------------------------------------------------------------------------------- 1 | # Binaries for programs and plugins 2 | *.exe 3 | *.dll 4 | *.so 5 | *.dylib 6 | binaries/ 7 | 8 | # Test binary, build with `go test -c` 9 | *.test 10 | 11 | # Output of the go coverage tool, specifically when used with LiteIDE 12 | *.out 13 | 14 | # Project-local glide cache, RE: https://github.com/Masterminds/glide/issues/736 15 | .glide/ 16 | 17 | # log files 18 | *.log 19 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /Makefile: -------------------------------------------------------------------------------- 1 | all: 2 | GOOS=windows GOARCH=386 go build -o binaries/respounder-win32.exe respounder.go 3 | GOOS=windows GOARCH=amd64 go build -o binaries/respounder-win64.exe respounder.go 4 | GOOS=linux GOARCH=386 go build -o binaries/respounder-linux32 respounder.go 5 | GOOS=linux GOARCH=amd64 go build -o binaries/respounder-linux64 respounder.go 6 | GOOS=darwin GOARCH=386 go build -o binaries/respounder-osx32 respounder.go 7 | GOOS=darwin GOARCH=amd64 go build -o binaries/respounder-osx64 respounder.go 8 | 9 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | 2 | 3 | # res·pound·er 4 | /rɪˈspaʊnd dər/ 5 | noun 6 | 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 | ![Respounder in action](https://i.imgur.com/ymcDRnJ.gif) 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 | --------------------------------------------------------------------------------