The discovery of a critical flaw in Windows Server that could allow a hacker to infiltrate an organisation’s network spurred US cyber security authorities to order all US agencies to patch their systems within four days.
The rare US Cybersecurity and Infrastructure Security Agency (CISA) directive, issued on 18 September, urged US government agencies to immediately patch the vulnerability tagged CVE-2020-1472 and rated 10.0 on the CVSS scale of severity.
The bug, dubbed ‘Zerologon’, is a critical flaw in Windows Server that allows attackers to compromise an Active Directory domain controller and grant themselves administration privileges, according to security firm Secura.
The flaw lies in Microsoft Windows Netlogon Remote Protocol (MS-NRPC), a core authentication component of Active Directory, and would only demand that an attacker has the power to set up TCP connections with a vulnerable domain controller. They wouldn’t require any domain credentials, and the vulnerability can be exploited to completely compromise all Active Directory identity services.
“By simply sending a number of Netlogon messages in which various fields are filled with zeroes, an attacker can change the computer password of the domain controller that is stored in the AD,” the Secura research said. “This can then be used to obtain domain admin credentials and then restore the original DC password.
“This attack has a huge impact: 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 vulnerability was patched on 11 August, and applying the update is the best mitigation against the attack. Its severity, however, has sparked CISA into ordering US government agencies to update their systems by 21 September over fears they’re being sluggish in that process.
RELATED RESOURCE
The definitive guide for choosing the right application delivery controller
Key considerations for an ADC
The patch that fixes Zerologon also implements additional measures that force domain-joined machines to use previously optional security features as part of the Netlogon remote protocol.
Although the patch blocks most steps as part of the exploit mechanism, Windows will log warning events when, for example, devices exist in the domain. Administrators can also activate an “enforcement mode” which mandates Secure NRPC for all devices.
A forthcoming patch in February next year aims to activate Secure NRPC by default, which may lead to some incompatibility issues with third-party devices and software. Administrators will then be required to update, decommission or whitelist devices that do not support Secure NRPC beforehand.
-
US companies dominate the European cloud market – regional players are left fighting for scrapsNews Synergy data shows EU providers hold just 15% of the market despite rise in AI and drive for cloud sovereignty
-
A flaw in Google’s new Gemini CLI tool could’ve allowed hackers to exfiltrate dataNews The company has moved to fix a vulnerability that allowed the execution of malicious code
-
Industry welcomes the NCSC’s new Vulnerability Research Initiative – but does it go far enough?News The cybersecurity agency will work with external researchers to uncover potential security holes in hardware and software
-
Edge devices are now your weakest link: VPNs, firewalls, and routers were the leading source of initial compromise in 30% of incidents last year – here’s whyNews Compromised network edge devices have rapidly emerged as one of the biggest attack points for small and medium businesses.
-
Hackers are targeting Ivanti VPN users again – here’s what you need to knowNews Ivanti has re-patched a security flaw in its Connect Secure VPN appliances that's been exploited by a China-linked espionage group since at least the middle of March.
-
Broadcom issues urgent alert over three VMware zero-daysNews The firm says it has information to suggest all three are being exploited in the wild
-
Nakivo backup flaw still present on some systems months after firms’ ‘silent patch’, researchers claimNews Over 200 vulnerable Nakivo backup instances have been identified months after the firm silently patched a security flaw.
-
Everything you need to know about the Microsoft Power Pages vulnerabilityNews A severe Microsoft Power Pages vulnerability has been fixed after cyber criminals were found to have been exploiting unpatched systems in the wild.
-
Billions of IoT devices will need to be secured in the next four years – zero trust could be the key to successNews Researchers have warned more than 28 billion IoT devices will need to be secured by 2028 as attacks on connected devices surge.
-
Cisco claims new smart switches provide next-level perimeter defenseNews Cisco’s ‘security everywhere’ mantra has just taken on new meaning with the launch of a series of smart network switches.
