Nearly 1 million Windows systems are still unpatched and have been found vulnerable to a recently disclosed critical, wormable, remote code execution vulnerability in the Windows Remote Desktop Protocol (RDP)—two weeks after Microsoft releases the security patch.

If exploited, the vulnerability could allow an attacker to easily cause havoc around the world, potentially much worse than what WannaCry and NotPetya like wormable attacks did in 2017.

Dubbed BlueKeep and tracked as CVE-2019-0708, the vulnerability affects Windows 2003, XP, Windows 7, Windows Server 2008 and 2008 R2 editions and could spread automatically on unprotected systems.

The vulnerability could allow an unauthenticated, remote attacker to execute arbitrary code and take control of a targeted computer just by sending specially crafted requests to the device's Remote Desktop Service (RDS) via the RDP—without requiring any interaction from a user.

Describing the BlueKeep vulnerability as being Wormable that could allow malware to propagate to vulnerable systems just like WannaCry, Microsoft released a security fix to address the vulnerability with its May 2019 Patch Tuesday updates.

However, the latest Internet scan performed by Robert Graham, head of offensive security research firm Errata Security, revealed that, unfortunately, roughly 950,000 publicly accessible machines on the Internet are vulnerable to the BlueKeep bug.

This clearly means that even after the security patch is out, not every user and organisation has deployed it to address the issue, posing a massive risk to individuals and organizations, including industrial and healthcare environments.

Graham used "rdpscan," a quick scanning tool he built on top of his masscan port scanner that can scan the entire Internet for systems still vulnerable to the BlueKeep vulnerability, and found a whole 7 million systems that were listening on port 3389, of which around 1 million systems are still vulnerable.

"Hackers are likely to figure out a robust exploit in the next month or two and cause havoc with these machines," the researcher says.

"That means when the worm hits, it'll likely compromise those million devices. This will likely lead to an event as damaging as WannaCry, and notPetya from 2017 -- potentially worse, as hackers have since honed their skills exploiting these things for ransomware and other nastiness."

The BlueKeep vulnerability has so much potential to wreak havoc worldwide that it forced Microsoft to release patches for not only the supported Windows versions but also Windows XP, Windows Vista and Windows Server 2003, which no longer receive mainstream support from the company but are still widely used.

Not just researchers, malicious hackers and cybercriminals have also started scanning the Internet for vulnerable Windows systems to target them with malware, GreyNoise Intelligence said.

"GreyNoise is observing sweeping tests for systems vulnerable to the RDP "BlueKeep" (CVE-2019-0708) vulnerability from several dozen hosts around the Internet. This activity has been observed from exclusively Tor exit nodes and is likely being executed by a single actor," the tweet says.

However, fortunately, so far no security researcher has yet publicly published any proof-of-concept exploit code for BlueKeep, though a few of them have confirmed to have successfully developed a working exploit.

Are you still waiting for me to tell you what you should do next? Go and fix the goddamn vulnerability if you are using one of them.

If fixing the flaw in your organisation is not possible anytime sooner, then you can take these mitigations:

• Disable RDP services, if not required.
• Block port 3389 using a firewall or make it accessible only over a private VPN.
• Enable Network Level Authentication (NLA) – this is partial mitigation to prevent any unauthenticated attacker from exploiting this Wormable flaw.