45 lines
1.7 KiB
Go
45 lines
1.7 KiB
Go
package services
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import (
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"bufio"
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"net"
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"strings"
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"time"
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)
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func NewTelnetHandler(log LoggerFunc) Handler {
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return func(conn net.Conn) {
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defer conn.Close()
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remote := conn.RemoteAddr().String()
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_, _ = conn.Write([]byte("\r\nUbuntu 20.04.3 LTS\r\n\r\nlogin: "))
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conn.SetDeadline(time.Now().Add(2 * time.Minute))
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scanner := bufio.NewScanner(conn)
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var username string
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expectingPassword := false
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inShell := false
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for scanner.Scan() {
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line := strings.TrimSpace(scanner.Text())
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if inShell {
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// fake shell: log the command and respond with minimal output
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cmd := line
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if cmd == "exit" || cmd == "logout" { _, _ = conn.Write([]byte("logout\r\n")); return }
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log(Record{Timestamp: Now(), RemoteAddr: remoteIP(remote), RemotePort: remotePort(remote), Service: "telnet", Details: map[string]string{"event":"shell_cmd","cmd":cmd}})
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_, _ = conn.Write([]byte("sh: " + cmd + ": command not found\r\n$ "))
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continue
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}
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if !expectingPassword {
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username = line
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log(Record{Timestamp: Now(), RemoteAddr: remoteIP(remote), RemotePort: remotePort(remote), Service: "telnet", Details: map[string]string{"event":"username_attempt","username":username}})
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_, _ = conn.Write([]byte("Password: "))
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expectingPassword = true
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} else {
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password := line
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log(Record{Timestamp: Now(), RemoteAddr: remoteIP(remote), RemotePort: remotePort(remote), Service: "telnet", Details: map[string]string{"event":"password_attempt","username":username,"password":password}})
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// drop into a fake shell prompt to encourage interaction
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_, _ = conn.Write([]byte("\r\nWelcome to Ubuntu 20.04.3 LTS (GNU/Linux 5.4.0-42-generic x86_64)\r\n$ "))
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inShell = true
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}
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}
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}
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}
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