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.

ABTV

10/11/2019
09:50 AM
Larry Loeb
Larry Loeb
Larry Loeb
50%
50%

New 'Reductor' Malware Intercepts Browser Traffic

Encrypted traffic from both Chrome and Firefox shown to be vulnerable.

Kaspersky has identifiedmalware that takes a novel approach to intercepting both Chrome and Firefox browsers' encrypted traffic. They have identified targets of the malware to be in Russia and Belarus.

First identified in April of this year, the new modules are named "Reductor" after a .pdb path Kaspersky found in some samples. Besides the typical RAT functions such as uploading, downloading and executing files, Reductor's authors impressed the Kaspersky researchers by putting a lot of effort into the manipulation of digital certificates and marking outbound TLS traffic with unique host-related identifiers.

Kaspersky tentatively linked it to the Turla APT, based on the victimology. Victimology alone is an unreliable attributor in most cases, however. Turla is the name of a Russian cyber espionage APT group (which has also been known as Waterbug, Venomous Bear and KRYPTON) that has been active since at least 2007 targeting government organizations and private businesses. The list of victims is long and is said to include the Swiss defense firm RUAG, US Department of State, and the US Central Command.

There are strong code similarities between this family and the COMPfun Trojan. In fact, Kaspersky says that, "Based on these similarities, we're quite sure the new malware was developed by the COMPfun authors."

The researchers say that Reductor spreads by either (1) infecting popular software distributions (Internet Downloader Manager, WinRAR, etc. and, for at least one case identified by the reasearchers, through a popular "warez" website over HTTP); or (2) its decryptor/dropper is spread through the use of COMpfun's ability to download files on hosts that have already been infected.

Marking the browser's TLS handshake without touching the traffic itself got the researchers' attention. It seems the malware developers analyzed the Firefox source code and Chrome binary code to patch the corresponding pseudo random number generation (PRNG) functions in the process's memory.

The researchers explain the method used by the malware in this way: "Browsers use PRNG to generate the 'client random' sequence for the network packet at the very beginning of the TLS handshake. Reductor adds encrypted unique hardware- and software-based identifiers for the victims to this 'client random' field. In order to patch the system's PRNG functions, the developers used a small embedded Intel instruction length disassembler."

Reductor adds its own "victim id" inside TLS packets. The first four-byte hash (cert_hash) is built using all of Reductor's digital certificates.

Kaspersky found that Reductor samples hold DER-encoded root X509v3 certificates in the .data section to add on the target hosts. The malware is also able to get additional certificates from the operators through a named pipe.

Rather interestingly, Reductor does not run a MitM attack itself. Yet the certificates that it installs would be a vital part of any such attack if such an attack were carried out.

Another idiosyncrasy of Reductor is that the malware's installation seems to be done "on the fly." The source installers that were seen by the researchers were not compromised themselves, but compromised browsers were delivered by them.

The entire methodology of the attack shows sophistication in execution, a sure indicator of a nation-state threat actor.

— 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
Edge-DRsplash-10-edge-articles
I Smell a RAT! New Cybersecurity Threats for the Crypto Industry
David Trepp, Partner, IT Assurance with accounting and advisory firm BPM LLP,  7/9/2021
News
Attacks on Kaseya Servers Led to Ransomware in Less Than 2 Hours
Robert Lemos, Contributing Writer,  7/7/2021
Commentary
It's in the Game (but It Shouldn't Be)
Tal Memran, Cybersecurity Expert, CYE,  7/9/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
How Enterprises are Attacking the Cybersecurity Problem
Concerns over supply chain vulnerabilities and attack visibility drove some significant changes in enterprise cybersecurity strategies over the past year. Dark Reading's 2021 Strategic Security Survey showed that many organizations are staying the course regarding the use of a mix of attack prevention and threat detection technologies and practices for dealing with cyber threats.
Flash Poll
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2021-42258
PUBLISHED: 2021-10-22
BQE BillQuick Web Suite 2018 through 2021 before 22.0.9.1 allows SQL injection for unauthenticated remote code execution, as exploited in the wild in October 2021 for ransomware installation. SQL injection can, for example, use the txtID (aka username) parameter. Successful exploitation can include ...
CVE-2020-28968
PUBLISHED: 2021-10-22
Draytek VigorAP 1000C contains a stored cross-site scripting (XSS) vulnerability in the RADIUS Setting - RADIUS Server Configuration module. This vulnerability allows attackers to execute arbitrary web scripts or HTML via a crafted payload in the username input field.
CVE-2020-28969
PUBLISHED: 2021-10-22
Aplioxio PDF ShapingUp 5.0.0.139 contains a buffer overflow which allows attackers to cause a denial of service (DoS) via a crafted PDF file.
CVE-2020-36485
PUBLISHED: 2021-10-22
Portable Ltd Playable v9.18 was discovered to contain an arbitrary file upload vulnerability in the filename parameter of the upload module. This vulnerability allows attackers to execute arbitrary code via a crafted JPEG file.
CVE-2020-36486
PUBLISHED: 2021-10-22
Swift File Transfer Mobile v1.1.2 and below was discovered to contain a cross-site scripting (XSS) vulnerability via the 'path' parameter of the 'list' and 'download' exception-handling.