文章目录
前记nim攻防基础FFI内存加载加解密、编码 后记C#类型转换表nim基础
前记
随便编写一个c#调用winapi并用vs生成dll,同时用csc生成exe
using System;using System.Runtime.InteropServices;namespace coleak{ class winfun { [DllImport("User32.dll")] public static extern int MessageBox(IntPtr h, string m, string c, uint type); [DllImport("kernel32.dll", EntryPoint = "Beep")] public static extern bool mymethod(uint frequency, uint duration); } class Program { static void Main(string[] args) { winfun winfun = new winfun(); winfun.MessageBox((IntPtr)0, "yueyy", "coleak",(uint) 0); Random random = new Random(); for (int i = 0; i < 10000; i++) { winfun.mymethod((uint)random.Next(10000), 100); } Console.ReadLine(); } }}/*BOOL Beep(DWORD dwFreq,DWORD dwDuration);int MessageBox( [in, optional] HWND hWnd, [in, optional] LPCTSTR lpText, [in, optional] LPCTSTR lpCaption, [in] UINT uType);*/优点：隐藏导入表，仅存在mscoree.dll
缺点：在dnspy下均直接出源码
nim攻防基础
为了更加OPSEC，考虑使用nim代替c#核心部分，nim防止反编译同时也不暴露导入函数
FFI
proc MessageBoxA*(hWnd: int, lpText: cstring, lpCaption: cstring, uType: int32): int32 {.discardable, dynlib: "user32", importc.}MessageBoxA(0, "Hello, world !", "MessageBox Example", 0)proc WinExec*(lpCmdLine:cstring,uCmdShow:int32): int32 {.discardable,dynlib:"kernel32",importc.}WinExec("calc.exe",0)proc printf(format: cstring): cint {.importc, varargs,discardable.}#discardable忽略返回值否则报错printf("My name is %s and I am %d years old!\n", "coleak", 20)proc mycmp(a, b: cstring): cint {.importc: "strcmp", nodecl.} #=proc strcmp(a, b: cstring): cint {.importc, nodecl.}let cmp = strcmp("Easy!", "Easy!")echo cmp嵌入c
when not defined(c): {.error: "Must be compiled in c mode"}{.emit: """#include <stdio.h>int Test() { char name[100]={0}; scanf("%s",name); printf("嵌入成功,%s",name); return 0; } // end main """.}proc Test(): int {.importc: "Test", nodecl,discardable.}when isMainModule: discard Test()内存加载
读取字节流
import osvar buf: array[4096,byte]var f: Filef = open(r"D:\c_project\nim\test.exe")discard readBytes(f, buf,0,4096)f.close()echo bufc.exe>aaa.txt
import winim/clrimport sugarimport osvar buf: array[4096,byte]buf = [77, 90, ..., 0]var assembly = load(buf)var arr = toCLRVariant(commandLineParams(), VT_BSTR)assembly.EntryPoint.Invoke(nil, toCLRVariant([arr]))c#虽然没有暴露导入信息，但是在hxd下会暴露字符串信息，因此在 Nim 编译的可执行文件中检测 .NET 程序集仍然很容易，还可以用hxd轻松搜到nim加载的程序集中存在的user32.dll字符信息和exe关键词
加解密、编码
base64
import base64import osimport strformatfunc toByteSeq*(str: string): seq[byte] {.inline.} = # Converts a string to the corresponding byte sequence @(str.toOpenArrayByte(0, str.high))let inFile: string = paramStr(1)let inFileContents: string = readFile(inFile)# To load this .NET assembly we need a byte array or sequencevar bytesequence: seq[byte] = toByteSeq(inFileContents)let encoded = encode(bytesequence)echo fmt"[*] Encoded: {encoded}"import base64import osimport strformatimport winim/clrimport sugarimport osfunc toByteSeq*(str: string): seq[byte] {.inline.} = # Converts a string to the corresponding byte sequence @(str.toOpenArrayByte(0, str.high))let encoded = r"TVqQAAMAAAAEAAAA//8...AAA=="let decoded = decode(encoded)let mys=toByteSeq(decoded)var assembly = load(mys)var arr = toCLRVariant(commandLineParams(), VT_BSTR)assembly.EntryPoint.Invoke(nil, toCLRVariant([arr]))可以换成别的方式加密.NET 程序集，用于运行时解密
后记
C#类型转换表
| Windows | C# |
|---|---|
| BOOL | int |
| BOOLEAN | byte |
| BYTE | byte |
| UCHAR | byte |
| UINT8 | byte |
| CCHAR | byte |
| CHAR | sbyte |
| CHAR | sbyte |
| INT8 | sbyte |
| CSHORT | short |
| INT16 | short |
| SHORT | short |
| ATOM | ushort |
| UINT16 | ushort |
| USHORT | ushort |
| WORD | ushort |
| INT | int |
| INT32 | int |
| LONG | int |
| LONG32 | int |
| CLONG | uint |
| DWORD | uint |
| DWORD32 | uint |
| UINT | uint |
| UINT32 | uint |
| ULONG | uint |
| ULONG32 | uint |
| INT64 | long |
| LARGE_INTEGER | long |
| LONG64 | long |
| LONGLONG | long |
| QWORD | long |
| DWORD64 | ulong |
| UINT64 | ulong |
| ULONG64 | ulong |
| ULONGLONG | ulong |
| ULARGE_INTEGER | ulong |
| HRESULT | int |
| NTSTATUS | int |
nim基础
语法速记
一、分支允许使用逗号分隔的值列表
let name = readLine(stdin)case nameof "": echo "Poor soul, you lost your name?"of "name": echo "Very funny, your name is name."of "Dave", "Frank": echo "Cool name!"else: echo "Hi, ", name, "!"二、of全覆盖
from strutils import parseIntecho "A number please: "let n = parseInt(readLine(stdin))case nof 0..2, 4..7: echo "The number is in the set: {0, 1, 2, 4, 5, 6, 7}"of 3, 8: echo "The number is 3 or 8"else: discard三、迭代器
echo "Counting down from 10 to 1: "for i in countup(1, 5): echo ifor i in countdown(6, 2): echo ifor i in 10..19: echo ifor i in 1..<19: echo i四、块语句
block myblock: echo "entering block" while true: echo "looping" break # 跳出循环,但不跳出块 echo "still in block"block myblock2: echo "entering block" while true: echo "looping" break myblock2 # 跳出块 (和循环) echo "still in block"五、缩进原则
# 单个赋值语句不需要缩进:if x: x = false# 嵌套if语句需要缩进:if x: if y: y = false else: y = true# 需要缩进, 因为条件后有两个语句：if x: x = false y = false六、函数
proc yes(question: string): bool = echo question, " (y/n)" while true: case readLine(stdin) of "y", "Y", "yes", "Yes": return true of "n", "N", "no", "No": return false else: echo "Please be clear: yes or no"if yes("Should I delete all your important files?"): echo "I'm sorry , I'm afraid I can't do that."else: echo "I think you know what the problem is just as well as I do." proc add(a:int,b:int):int= return a+becho add(1,89)proc sumTillNegative(x: varargs[int]): int = for i in x: if i < 0: return result = result + iecho sumTillNegative() # echos 0echo sumTillNegative(3, 4, 5) # echos 12函数定义格式看起来很繁琐，返回值类型放在: bool =
result 总在过程的结尾自动返回如果退出时没有 return语句
七、传实参
proc divmod(a, b: int; res: var int,remainder:var int) = res = a div b # 整除 remainder = a mod b # 整数取模操作var x, y=111divmod(8, 5, x, y) # 修改x和yecho xecho y传递实参用var修饰
八、忽略返回值discard
proc p(x, y: int): int {.discardable.} = return x + yvar c:intc=p(3, 4) # now validecho cp(3, 4)九、数组初始化
type IntArray = array[0..7, int] # 一个索引为0..7的数组 QuickArray = array[6, int] # 一个索引为0..5的数组var x: IntArrayx = [1, 5, 3, 4, 5, 77,9,8]for i in low(x)..high(x): echo x[i]for i in x: echo i for i, v in @[3, 7, 5]: echo "index: ", $i, ", value:", $v# --> index: 0, value:3# --> index: 1, value:4# --> index: 2, value:5十、结构体
type Person = object name: string age: intvar person1 = Person(name: "Peter", age: 30)echo person1.name # "Peter"echo person1.age # 30var person2 = person1 # 复制person 1十一、读写文件
#字节流import osvar buf: array[100,byte]var f: Filef = open("D:\\c_project\\nim\\d.exe")discard readBytes(f, buf,0,9)f.close()echo buf#文本文件var file:Filefile = open(r"D:\c_project\nim\d.txt")echo file.readAll()file.close()let text = "Cats are very cool!"writeFile("cats.txt", text)十二、绝对路径默认目录为shell路径