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.

Security Management

8/29/2019
11:30 AM
Larry Loeb
Larry Loeb
Larry Loeb
50%
50%

AV Vendor & French Gendarmerie Take Down a Transnational Worm

The good guys got lucky this time.

The good guys won one. It took a commercial AV vendor teaming up with the French Gendarmerie to make it happen, but happen it did.

Let's start at the beginning. Retadup is a malicious worm affecting Windows machines located in Latin America. It tries to achieve persistence on its victims' computers, to spread itself far and wide and to install additional malware payloads on infected machines. Usually, it's malware mining cryptocurrency on the malware authors' behalf. But Stop ransomware and the Arkei password stealer has also been seen using the worm.

AV vendor Avast first looked at the worm in detail and started monitoring its activity closely in March 2019. How it was evading Avast's AV detection piqued the company's interest.

Avast described what it found in the blog that it posted about the effort. "After analyzing Retadup more closely," it said, "we found that while it is very prevalent, its C&C [command and control] communication protocol is quite simple. We identified a design flaw in the C&C protocol that would have allowed us to remove the malware from its victims' computers had we taken over its C&C server. This made it possible to put an end to Retadup and protect everyone from it, not just Avast users (note that while it is often possible to clean malware infections by taking over a C&C server and pushing a 'malware removal' script to the victims through the malware's established arbitrary code execution channel, the design flaw we found did not involve making the victims execute any extra code)."

Avast found a way to kill the C&C server and the malware with one action.

Retadup's C&C infrastructure was mostly located in France so Avast decided to contact the French National Gendarmerie at the end of March to share what it had found.

Les flics gave their own cooperation. They obtained a snapshot of the C&C server's disk from its hosting provider and shared parts of it (no PII!) with Avast so they could start to reverse engineer the contents of the C&C server.

In July 2019, the Gendarmerie received the green light to proceed with the disinfection. They replaced the malicious C&C server with a prepared by Avast disinfection server that made connected instances of Retadup self-destruct.

Some parts of the C&C infrastructure were found to be located in the US. The Gendarmerie alerted the FBI who took them down on July 8. Avast was able to determine post-mortem the most infected computers had either two or four cores (the average number of infected computer cores was 2.94) and that the majority of victims used Windows 7. Over 85% of Retadup's victims also had no third-party antivirus software installed.

The good guys got lucky this time. A flaw in the malware could be exploited to cause its downfall. The next time luck may not be a factor.

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Cloud Security Threats for 2021
Or Azarzar, CTO & Co-Founder of Lightspin,  12/3/2020
Why Vulnerable Code Is Shipped Knowingly
Chris Eng, Chief Research Officer, Veracode,  11/30/2020
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win an Amazon Gift Card! Click Here
Latest Comment: This comment is waiting for review by our moderators.
Current Issue
2021 Top Enterprise IT Trends
We've identified the key trends that are poised to impact the IT landscape in 2021. Find out why they're important and how they will affect you today!
Flash Poll
Assessing Cybersecurity Risk in Todays Enterprises
Assessing Cybersecurity Risk in Todays Enterprises
COVID-19 has created a new IT paradigm in the enterprise and a new level of cybersecurity risk. This report offers a look at how enterprises are assessing and managing cyber-risk under the new normal.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2020-27772
PUBLISHED: 2020-12-04
A flaw was found in ImageMagick in coders/bmp.c. An attacker who submits a crafted file that is processed by ImageMagick could trigger undefined behavior in the form of values outside the range of type `unsigned int`. This would most likely lead to an impact to application availability, but could po...
CVE-2020-27773
PUBLISHED: 2020-12-04
A flaw was found in ImageMagick in MagickCore/gem-private.h. An attacker who submits a crafted file that is processed by ImageMagick could trigger undefined behavior in the form of values outside the range of type `unsigned char` or division by zero. This would most likely lead to an impact to appli...
CVE-2020-28950
PUBLISHED: 2020-12-04
The installer of Kaspersky Anti-Ransomware Tool (KART) prior to KART 4.0 Patch C was vulnerable to a DLL hijacking attack that allowed an attacker to elevate privileges during installation process.
CVE-2020-27774
PUBLISHED: 2020-12-04
A flaw was found in ImageMagick in MagickCore/statistic.c. An attacker who submits a crafted file that is processed by ImageMagick could trigger undefined behavior in the form of a too large shift for 64-bit type `ssize_t`. This would most likely lead to an impact to application availability, but co...
CVE-2020-27775
PUBLISHED: 2020-12-04
A flaw was found in ImageMagick in MagickCore/quantum.h. An attacker who submits a crafted file that is processed by ImageMagick could trigger undefined behavior in the form of values outside the range of type unsigned char. This would most likely lead to an impact to application availability, but c...