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.

Attacks/Breaches

6/8/2016
08:30 PM
Connect Directly
Twitter
LinkedIn
RSS
E-Mail
50%
50%

Zcrypt Ransomware: Old Wine In A New Bottle

Malware authors have combined old and new approaches to try and sneak Zcrypt past defenses, Check Point says.

Malware typically garners attention for introducing sneaky new tactics and techniques to infiltrate systems and propagate: Zcrypt is getting attention for doing the opposite.

Zcrypt is a newly discovered ransomware sample that security vendor Check Point profiled in a report this week. What sets it apart from the slew of ransomware tools floating in the wild is its use of older techniques along with new ones in order propagate and to evade detection by anti-malware tools optimized to look for newer threats.

In addition to spreading via phishing emails and exploit kits like many reansomware variants, Zcrypt also propagates via USBs. When an infected USB is plugged into a system, Zcrypt automatically launches a file called invoice.exe, which when opened infects the system with the ransomware.

“The Autorun technique for spreading used to be very common about three years ago,” says Tamara Leiderfarb, technology leader at Check Point. “It’s much slower than any other technique that moves through the network, but on the other hand, it is under the radar and does not require credentials.”

The use of USBs also provides a way for Zcrypt to propagate to network segments that would otherwise not be available, Leiderfarb says.

Zcrypt also writes using a dynamic-link library (DLL) file. To unpack the DLL file, Zcrypt uses a process called the Nullsoft Scriptable Install System (NSIS), which is also used by legitimate applications. Running code in DLLs is a relatively older technique, Leiderfarb says. It is designed to evade detection in sandboxes since the malware simply will not run in most cases.

Unlike many ransomware samples, Zcrypt does not attempt to delete shadow copies, delete itself, or copy itself several times before initiating, she says. It is pretty straightforward in that it encrypts and corrupts files to prevent recovery. Zcrypt’s ability to run in different process instances and its use of packers allow it to evade detection by anti-malware tools.

The use of older techniques does not make Zcyrpt any less potent than other sophisticated ransomware threats, however. Zcrypt is designed to overwrite targeted files not once, but twice. It first corrupts the file and then encrypts it to limit the ability of victims to use disk recovery tools. After encrypting target files, Zcrypt monitors for file changes and promptly encrypts any new files on the compromised system.

The mix of older techniques in Zcrypt is interesting and suggests that ransomware purveyors are trying different tacks to sneak their malware past malware defenses, Leiderfarb says. It is the second ransomware tool in recent months—the other being CryptXXX—to use the approach, and it is quite likely there will be other ransomware samples attempting to do the same thing, Leiderfarb says.

“Ransomware attacks have become much more simplistic to evade the security measures put against them,” she says. “In the beginning, ransomware attacks often tried to be innovative and their developers realized these innovations caused their detection. By scaling back, less innovative ransomware attacks have actually become more evasive.”

Security vendor ESET this week warned of a new ransomware family dubbed Crysis that it said has quickly emerged as a significant threat following the recent cessation of the TeslaCrypt ransomware operation.

ESET says Crysis is designed to encrypt files on fixed, removable, and network drives. The malware is being spread via attachments in spam emails, using double file extension. “Using this simple – yet effective – technique, executable files appear as non-executable,” ESET researcher Ondrej Kubovic wrote. The authors of Crysis have also been using malicious files disguised as seemingly harmless installers for legitimate applications to distribute the ransomware, Kubovic said.

Related stories

 

Jai Vijayan is a seasoned technology reporter with over 20 years of experience in IT trade journalism. He was most recently a Senior Editor at Computerworld, where he covered information security and data privacy issues for the publication. Over the course of his 20-year ... View Full Bio
 

Recommended Reading:

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Commentary
What the FedEx Logo Taught Me About Cybersecurity
Matt Shea, Head of Federal @ MixMode,  6/4/2021
Edge-DRsplash-10-edge-articles
A View From Inside a Deception
Sara Peters, Senior Editor at Dark Reading,  6/2/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
The State of Cybersecurity Incident Response
In this report learn how enterprises are building their incident response teams and processes, how they research potential compromises, how they respond to new breaches, and what tools and processes they use to remediate problems and improve their cyber defenses for the future.
Flash Poll
How Enterprises are Developing Secure Applications
How Enterprises are Developing Secure Applications
Recent breaches of third-party apps are driving many organizations to think harder about the security of their off-the-shelf software as they continue to move left in secure software development practices.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2021-23394
PUBLISHED: 2021-06-13
The package studio-42/elfinder before 2.1.58 are vulnerable to Remote Code Execution (RCE) via execution of PHP code in a .phar file. NOTE: This only applies if the server parses .phar files as PHP.
CVE-2021-34682
PUBLISHED: 2021-06-12
Receita Federal IRPF 2021 1.7 allows a man-in-the-middle attack against the update feature.
CVE-2021-31811
PUBLISHED: 2021-06-12
In Apache PDFBox, a carefully crafted PDF file can trigger an OutOfMemory-Exception while loading the file. This issue affects Apache PDFBox version 2.0.23 and prior 2.0.x versions.
CVE-2021-31812
PUBLISHED: 2021-06-12
In Apache PDFBox, a carefully crafted PDF file can trigger an infinite loop while loading the file. This issue affects Apache PDFBox version 2.0.23 and prior 2.0.x versions.
CVE-2021-32552
PUBLISHED: 2021-06-12
It was discovered that read_file() in apport/hookutils.py would follow symbolic links or open FIFOs. When this function is used by the openjdk-16 package apport hooks, it could expose private data to other local users.