U.S. government officials have warned that advanced persistent threat actors (APTs) are now leveraging Microsoft’s severe privilege-escalation flaw, dubbed “Zerologon,” to target elections support systems.
Days after Microsoft sounded the alarm that an Iranian nation-state actor was actively exploiting the flaw (CVE-2020-1472), the Cybersecurity Infrastructure Security Agency (CISA) and the Federal Bureau of Investigation (FBI) published a joint advisory warning of further attacks.
The advisory details how attackers are chaining together various vulnerabilities and exploits – including using VPN vulnerabilities to gain initial access and then Zerologon as a post-exploitation method – to compromise government networks.
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“This recent malicious activity has often, but not exclusively, been directed at federal and state, local, tribal and territorial (SLTT) government networks,” according to the security advisory. “Although it does not appear these targets are being selected because of their proximity to elections information, there may be some risk to elections information housed on government networks.”
With the U.S. November presidential elections around the corner – and cybercriminal activity subsequently ramping up to target election infrastructure and presidential campaigns – election security is top of mind. While the CISA and FBI’s advisory did not detail what type of elections systems were targeted, it did note that there is no evidence to support that the “integrity of elections data has been compromised.”
Microsoft released a patch for the Zerologon vulnerability as part of its August 11, 2020 Patch Tuesday security updates. Exploiting the bug allows an unauthenticated attacker, with network access to a domain controller, to completely compromise all Active Directory identity services, according to Microsoft.
Despite a patch being issued, many companies have not yet applied the patches to their systems – and cybercriminals are taking advantage of that in a recent slew of government-targeted attacks.
The CISA and FBI warned that various APT actors are commonly using a Fortinet vulnerability to gain initial access to companies. That flaw (CVE-2018-13379) is a path-traversal glitch in Fortinet’s FortiOS Secure Socket Layer (SSL) virtual private network (VPN) solution. While the flaw was patched in April 2019, exploitation details were publicized in August 2019, opening the door for attackers to exploit the error.
Other initial vulnerabilities being targeted in the attacks include ones in Citrix NetScaler (CVE-2019-19781), MobileIron (CVE-2020-15505), Pulse Secure (CVE-2019-11510), Palo Alto Networks (CVE-2020-2021) and F5 BIG-IP (CVE-2020-5902).
After exploiting an initial flaw, attackers are then leveraging the Zerologon flaw to escalate privileges, researchers said. They then use legitimate credentials to log in via VPN or remote-access services, in order to maintain persistence.
“The actors are leveraging CVE-2020-1472 in Windows Netlogon to escalate privileges and obtain access to Windows AD servers,” they said. “Actors are also leveraging the opensource tools such as Mimikatz and the CrackMapExec tool to obtain valid account credentials from AD servers.”
The advisory comes as exploitation attempts against Zerologon spike, with Microsoft recently warned of exploits by an advanced persistent threat (APT) actor, which the company calls MERCURY (also known as MuddyWater, Static Kitten and Seedworm). Cisco Talos researchers also recently warned of a spike in exploitation attempts against Zerologon.
Earlier in September, the stakes got higher for risks tied to the bug when four public proof-of-concept exploits for the flaw were released on Github. This spurred the Secretary of Homeland Security to issue a rare emergency directive, ordering federal agencies to patch their Windows Servers against the flaw by Sept. 2.
CISA and the FBI stressed that organizations should ensure their systems are patched, and adopt an “assume breach” mentality. Satnam Narang, staff research engineer with Tenable, agreed, saying that “it seems clear that Zerologon is becoming one of the most critical vulnerabilities of 2020.”
“Patches are available for all of the vulnerabilities referenced in the joint cybersecurity advisory from CISA and the FBI,” said Narang in a Monday analysis. “Most of the vulnerabilities had patches available for them following their disclosure, with the exception of CVE-2019-19781, which received patches a month after it was originally disclosed.”
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