Tech

New Windows exploit lets you instantly become admin. Have you patched?

139Views
EnlargeVGrigas (WMF)

Researchers have developed and published a proof-of-concept exploit for a recently patched Windows vulnerability that can allow access to an organizations crown jewels—the Active Directory domain controllers that act as an all-powerful gatekeeper for all machines connected to a network.

CVE-2020-1472, as the vulnerability is tracked, carries a critical severity rating from Microsoft as well as a maximum of 10 under the Common Vulnerability Scoring System. Exploits require that an attacker already have a foothold inside a targeted network, either as an unprivileged insider or through the compromise of a connected device.

An “insane” bug with “huge impact”

Such post-compromise exploits have become increasingly valuable to attackers pushing ransomware or espionage spyware. Tricking employees to click on malicious links and attachments in email is relatively easy. Using those compromised computers to pivot to more valuable resources can be much harder.

It can sometimes take weeks or months to escalate low-level privileges to those needed to install malware or execute commands. Enter Zerologon, an exploit developed by researchers from security firm Secura. It allows attackers to instantly gain control of the Active Directory. From there, they will have free rein to do just about anything they want, from adding new computers to the network to infecting each one with malware of their choice.

“This attack has a huge impact,” researchers with Secura wrote in a white paper published on Friday. “It basically allows any attacker on the local network (such as a malicious insider or someone who simply plugged in a device to an on-premise network port) to completely compromise the Windows domain. The attack is completely unauthenticated: the attacker does not need any user credentials.”

The Secura researchers, who discovered the vulnerability and reported it to Microsoft, said they developed an exploit that works reliably, but given the risk, they arent releasing it until theyre confident Microsofts patch has been widely installed on vulnerable servers. The researchers, however, warned that its not hard to use Microsofts patch to work backwards and develop an exploit. Meanwhile, separate researchers other security firms have published their own proofs-of-concept attack code here, here, and here.

The release and description of exploit code quickly caught the attention of the US Cybersecurity and Infrastructure Security Agency, which works to improve cybersecurity across all levels of government. Twitter on Monday was also blowing up with comments remarking on the threat posed by the vulnerability.

“Zerologon (CVE-2020-1472), the most insane vulnerability ever!” one Windows user wrote. “Domain Admin privileges immediately from unauthenticated network access to DC.”

“Remember something about least privileged access and that it doesnt matter if few boxes gets pwned?” Zuk Avraham, a researcher who is founder and CEO of security firm ZecOps, wrote. “Oh well… CVE-2020-1472 / #Zerologon is basically going to change your mind.”

We can't just ignore attackers when they don't cause damage. We can't just wipe computers with malware / issues without looking into the problems first. We can't just restore an image without checking which other assets are infected / how the malware got in.

— Zuk (@ihackbanme) September 14, 2020

Keys to the kingdom

Zerologon works by sending a string of zeros in a series of messages that use the Netlogon protocol, which Windows serversRead More – Source