Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Perimeter

5/13/2019
05:25 PM
Connect Directly
Twitter
LinkedIn
Google+
RSS
E-Mail
50%
50%

LockerGoga, MegaCortex Ransomware Share Unlikely Traits

New form of ransomware MegaCortex shares commonalities with LockerGoga, enterprise malware recently seen in major cyberattacks.

MegaCortex, a newly discovered form of ransomware that targets global organizations, was found to share similarities with LockerGoga, a known form of malware seen in enterprise attacks.

Sophos researchers published initial findings related to MegaCortex late last week. The active ransomware variant sends victims a note designed to read as if it's from Morpheus, Laurence Fishburne's character in The Matrix. MegaCortex was spotted hitting several enterprise customers across the US, Europe, and Canada, with 47 attack attempts within a 48-hour period.

A few traits of MegaCortex made the campaign stand out. Victims reported the attacks originated from a compromised domain controller, and adversaries used stolen admin credentials to run a PowerShell script using the compromised controller — both traits that make it unique, says Jessica Bair, senior manager of advanced threat solutions at Cisco Systems.

Researchers note this ransomware is mostly seen among businesses with existing Emotet and Qbot infections, both of which can be used as launching points to distribute other malware. Given this, organizations previously exposed to either threat should prioritize remediation.

In the week since its early findings were disclosed, the Sophos team has become aware of more attacks involving MegaCortex and updated their research to reflect additional data on the tools, techniques, and other specifics that were not known at the time of publication.

"Since last week we have learned a lot more of the small details about the behavior and tooling used by MegaCortex," says Chet Wisniewski, Sophos' principal research scientist. "Many of these details are similar or identical to another ransomware named LockerGoga," however, there isn't much code similarity between them. Still, there are a few interesting similarities:

Links to LockerGoga
LockerGoga is a form of ransomware recently used in a major cyberattack against Norwegian aluminum firm Norsk Hydro, where it disrupted critical operations across North America and Europe. The incident forced Norsk Hydro to transition to manual operations at multiple plants; so far, it has cost the manufacturer $40 million. Once on a system, LockerGoga, which appears to be designed for targeted campaigns, changes passwords and forcibly logs victims out of systems.

The two forms of ransomware appear to behave the same way, Wisniewski explains. In both, operators leverage a compromised domain controller to push malware out to machines on a target network. From there, they open a reverse shell from the internal network to one of their command-and-control (C2) servers to execute the attacks. At least one of the C2 addresses that MegaCortex contacts has also been used by LockerGoga, researchers explain in a blog post.

MegaCortex also renames the files it plans to encrypt before encrypting them, which is unusual for ransomware — except LockerGoga, which does the same. "We suspect this may be used to prevent the malware from unintentionally encrypting files twice on an infected machine," says Wisniewski. The tactic has another effect: it makes those renamed files "un-double-clickable" as it removes the file type association of the document with its parent application.

One of the most obvious similarities is the batch file used in the attack, Wisniewski continues. Many researchers think it's "virtually identical" to batch files used to kill processes during LockerGoga attacks. Still, he says, none of the individual similarities are enough to make any attribution to MegaCortex's origin. At this time, they remain a "large number of interesting coincidences."

Contemplating Cryptographic Certificates
MegaCortex uses signed binaries with the common name (CN) mimicking the same CN used in the signed binaries of completely unrelated malware families. For example, researchers queried a CN on the cryptographic certificate used to sign one of the MegaCortex malware executables. They found malware from Rietspoof, a financial-services credential stealer with no code similarity or link to MegaCortex.

"We're not sure why they would do this," says Wisniewski. "Often things are thrown in to confuse those investigating the attacks, a sort of 'false flag operation.'" The certificates for MegaCortex were issued by different authorities from the certificates they were mimicking; for example, that of Rietspoof. Some certificate authorities are now revoking the certificates used in MegaCortex attacks, Wisniewski says.

Investigation into certificates yielded another interesting finding: researchers noticed the address used by the certificate — a street address located in London suburb Romford — is connected to more than 74,000 registered UK businesses. There is also evidence the same address has been used in signing certificates that were then used to sign unrelated malware binaries. They're still looking into this.

"We do not really understand how an apparent residential address ended up being used as a business address for some 74,000+ companies currently or formerly registered in the UK," says Wisniewski, who adds that site for The Companies House — the United Kingdom's registrar for companies — permits visitors to access only the first 1,000 records of this search.

Related Content:

 

 

 

Join Dark Reading LIVE for two cybersecurity summits at Interop 2019. Learn from the industry's most knowledgeable IT security experts. Check out the Interop agenda here.

Kelly Sheridan is the Staff Editor at Dark Reading, where she focuses on cybersecurity news and analysis. She is a business technology journalist who previously reported for InformationWeek, where she covered Microsoft, and Insurance & Technology, where she covered financial ... View Full Bio
 

Recommended Reading:

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
COVID-19: Latest Security News & Commentary
Dark Reading Staff 7/9/2020
Omdia Research Launches Page on Dark Reading
Tim Wilson, Editor in Chief, Dark Reading 7/9/2020
4 Security Tips as the July 15 Tax-Day Extension Draws Near
Shane Buckley, President & Chief Operating Officer, Gigamon,  7/10/2020
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
Special Report: Computing's New Normal, a Dark Reading Perspective
This special report examines how IT security organizations have adapted to the "new normal" of computing and what the long-term effects will be. Read it and get a unique set of perspectives on issues ranging from new threats & vulnerabilities as a result of remote working to how enterprise security strategy will be affected long term.
Flash Poll
The Threat from the Internetand What Your Organization Can Do About It
The Threat from the Internetand What Your Organization Can Do About It
This report describes some of the latest attacks and threats emanating from the Internet, as well as advice and tips on how your organization can mitigate those threats before they affect your business. Download it today!
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2020-15105
PUBLISHED: 2020-07-10
Django Two-Factor Authentication before 1.12, stores the user's password in clear text in the user session (base64-encoded). The password is stored in the session when the user submits their username and password, and is removed once they complete authentication by entering a two-factor authenticati...
CVE-2020-11061
PUBLISHED: 2020-07-10
In Bareos Director less than or equal to 16.2.10, 17.2.9, 18.2.8, and 19.2.7, a heap overflow allows a malicious client to corrupt the director's memory via oversized digest strings sent during initialization of a verify job. Disabling verify jobs mitigates the problem. This issue is also patched in...
CVE-2020-4042
PUBLISHED: 2020-07-10
Bareos before version 19.2.8 and earlier allows a malicious client to communicate with the director without knowledge of the shared secret if the director allows client initiated connection and connects to the client itself. The malicious client can replay the Bareos director's cram-md5 challenge to...
CVE-2020-11081
PUBLISHED: 2020-07-10
osquery before version 4.4.0 enables a priviledge escalation vulnerability. If a Window system is configured with a PATH that contains a user-writable directory then a local user may write a zlib1.dll DLL, which osquery will attempt to load. Since osquery runs with elevated privileges this enables l...
CVE-2020-6114
PUBLISHED: 2020-07-10
An exploitable SQL injection vulnerability exists in the Admin Reports functionality of Glacies IceHRM v26.6.0.OS (Commit bb274de1751ffb9d09482fd2538f9950a94c510a) . A specially crafted HTTP request can cause SQL injection. An attacker can make an authenticated HTTP request to trigger this vulnerabi...