On Monday May 28, 2018, during routine operations, Cofense Intelligence™ identified traits across several campaigns that indicated they were linked. In fact, this discovery helped to reveal a sprawling criminal enterprise that uses linked infrastructure to host nearly 100 domains, along with corresponding malware campaigns.
On the 19th of April, the Cofense Phishing Defense Center received an email crafted to appear to be from “Sberbank Russia.” In fact, it was a phishing email containing the Troldesh malware, a variant of Russian Ransomware first seen in mid-2015. The PDC hadn’t seen this variant for quite some time.
By Jerome Doaty, Zakari Grater, and Brenda Gooshaw Samson
Technology is an important part of any phishing defense, especially perimeter tech designed to filter emails. But these systems, even those billed as “next-gen email security platforms,” don’t catch everything. Some phishes always get through.
Most security teams today are pretty much in the same boat: limited budget, limited man power, and limited time to defend their network against escalating threats and attacks. Perhaps that’s why so many information security vendors claim to have the “silver bullet” to protect the customer’s environment and solve their problems.
Imagine a cunning phisher: he knows his craft and sends your users an email appearing to come from your CEO that bypasses all your other technology. What would you do?
One of our customers faced that very scenario and relied on Cofense TriageTM and the Cofense Phishing Defense Center (PDC) to analyze and respond to the attack in less than 20 minutes after it launched.
On March 22nd, Cofense came across a rather unique malware sample that had a very low detection rate. At the time of analysis, the file was only detected by 5/61 AV engines. The detection rate did not reach 30% until at least a week later, as per VirusTotal: 38015eb1699b7596e8c95fed7f0bc32d1492b371bd4d7953019f69dcf40ff1fd.
New additions to the TrickBot malware’s capabilities, observed by the Phishing Defence Centre, indicate that this malware tool is undergoing active development. The designers of this malware are still working hard to introduce new functionality including a network worm functionality and a screen-lock module. The worm component utilises the leaked “EternalBlue” exploit for CVE-2017-0144 to propagate itself across networks that have yet to patch or discontinue the use of SMBv1. The deployment of the screen-lock module (which appears to be still in the early phases of development) gives the threat actors the ability to change the functionality of the malware from robust banking trojan to a rudimentary ransomware.
Many gamers are unaware that they are either potential targets for mining botnets or that they may already be mining cryptocurrencies for cybercriminals.
Why are gamers targets? Think about it. Mining requires a large graphics card (GPU), a dedicated Internet connection and an uninterrupted power source. Gamers use powerful and immersive, high-performing GPU’s to stay online and play networked games without interruption. It’s the perfect recipe for crypto mining.
Adding to a growing trend of phishing attacks wherein Windows and Office functionalities are abused to compromise victim systems, Cofense Intelligence™ has analyzed a recent campaign that uses the URL file type to deliver subsequent malware payloads. This file type is similar to a Windows LNK shortcut file (both file types share the same global object identifier within Windows) and can be used as a shortcut to online locations or network file shares. These files may abuse built-in functionality in Windows to enhance the ability of an attacker to deliver malware to endpoints.
By abusing these built-in functionalities, threat actors can complicate detection and mitigation in these scenarios, because the software is behaving exactly as it was designed to. The proliferation of abuse techniques indicates that threat actors may be increasingly prioritizing the use of such methodologies due to detection difficulties.
The emails analyzed by Cofense Intelligence include a nondescript phishing campaign that informs recipients of an attached bill, receipt, or invoice. The analysis performed for Threat ID 10993 focused on emails that deliver attached URL shortcut files with their target resource identified using the “file://” scheme. Windows environments use this scheme to denote a file resource that is on the hard drive or hosted on a network file share.
However, the target for these Uniform Resource Identifiers (URIs) can also be a remote resource. When a URL shortcut file is written to disk, Windows will attempt to validate the target denoted by the “file://” scheme. If validated, the remote resource can be downloaded to the local machine. The use of this file format and URI scheme may indicate that threat actors seek to abuse the resource resolution functionality associated with these shortcut files to deliver malware onto victims’ machines at the time the URL file is extracted from a Zip archive.
Figure 1 – URL shortcut files can reference remote file shares to deliver malware
Figure 2 – Downloading a payload over SMB is a less-common method for malware delivery
This technique showcases yet another method in which commonplace Windows features are abused by threat actors, adding to the expanding set of delivery applications crafted to distribute malware.
The nature of these files reveals the risk involved with applications that obtain files simply by issuing connection requests without user interaction. Incident responders and network defenders must devise a response plan to address this scenario, especially if enterprises and organizations operate on a Windows environment. This campaign also demonstrates that as threat actors develop new attack methodologies, more emails are likely to reach user inboxes. Therefore, it is crucial that those users can identify and report such campaigns, because they are the final line of defense at that point.
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