Apr 11, 2024NewsroomEndpoint Security / Ransomware

A threat actor tracked as TA547 has targeted dozens of German organizations with an information stealer called Rhadamanthys as part of an invoice-themed phishing campaign.

“This is the first time researchers observed TA547 use Rhadamanthys, an information stealer that is used by multiple cybercriminal threat actors,” Proofpoint said. “Additionally, the actor appeared to use a PowerShell script that researchers suspect was generated by a large language model (LLM).”

TA547 is a prolific, financially motivated threat actor that’s known to be active since at least November 2017, using email phishing lures to deliver a variety of Android and Windows malware such as ZLoader, Gootkit, DanaBot, Ursnif, and even Adhubllka ransomware.

In recent years, the group has evolved into an initial access broker (IAB) for ransomware attacks. It has also been observed employing geofencing tricks to restrict payloads to specific regions.

The email messages observed as part of the latest campaign impersonate the German company Metro AG and contain a password-protected ZIP file containing a ZIP archive that, when opened, initiates the execution of a remote PowerShell script to launch the Rhadamanthys stealer directly in memory.

Interestingly, the PowerShell script used to load Rhadamanthys includes “grammatically correct and hyper specific comments” for each instruction in the program, raising the possibility that it may have been generated (or rewritten) using an LLM.

The alternate hypothesis is that TA547 copied the script from another source that had used generative AI technology to create it.

“This campaign represents an example of some technique shifts from TA547 including the use of compressed LNKs and previously unobserved Rhadamanthys stealer,” Proofpoint said. “It also provides insight into how threat actors are leveraging likely LLM-generated content in malware campaigns.”

The development comes as phishing campaigns have also been banking on uncommon tactics to facilitate credential-harvesting attacks. In these emails, recipients are notified of a voice message and are directed to click on a link to access it.

The payload retrieved from the URL is heavily obfuscated HTML content that runs JavaScript code embedded within an SVG image when the page is rendered on the target system.

Present within the SVG data is “encrypted data containing a second stage page prompting the target to enter their credentials to access the voice message,” Binary Defense said, adding the page is encrypted using CryptoJS.

Other email-based attacks have paved the way for Agent Tesla, which has emerged as an attractive option for threat actors due to it “being an affordable malware service with multiple capabilities to exfiltrate and steal users’ data,” according to Cofense.

Social engineering campaigns have also taken the form of malicious ads served on search engines like Google that lure unsuspecting users into downloading bogus installers for popular software like PuTTY, FileZilla, and Room Planner to ultimately deploy Nitrogen and IDAT Loader.

The infection chain associated with IDAT Loader is noteworthy for the fact that the MSIX installer is used to launch a PowerShell script that, in turn, contacts a Telegram bot to fetch a second PowerShell script hosted on the bot.

This PowerShell script then acts as a conduit to deliver another PowerShell script that’s used to bypass Windows Antimalware Scan Interface (AMSI) protections as well as trigger the execution of the loader, which subsequently proceeds to load the SectopRAT trojan.

“Endpoints can be protected from malicious ads via group policies that restrict traffic coming from the main and lesser known ad networks,” Jérôme Segura, principal threat researcher at Malwarebytes, said.

Dec 27, 2023NewsroomPrivacy / App Security

A new Android backdoor has been discovered with potent capabilities to carry out a range of malicious actions on infected devices.

Dubbed Xamalicious by the McAfee Mobile Research Team, the malware is so named for the fact that it’s developed using an open-source mobile app framework called Xamarin and abuses the operating system’s accessibility permissions to fulfill its objectives.

It’s also capable of gathering metadata about the compromised device and contacting a command-and-control (C2) server to fetch a second-stage payload, but only after determining if it fits the bill.

The second stage is “dynamically injected as an assembly DLL at runtime level to take full control of the device and potentially perform fraudulent actions such as clicking on ads, installing apps, among other actions financially motivated without user consent,” security researcher Fernando Ruiz said.

The cybersecurity firm said it identified 25 apps that come with this active threat, some of which were distributed on the official Google Play Store since mid-2020. The apps are estimated to have been installed at least 327,000 times.

A majority of the infections have been reported in Brazil, Argentina, the U.K., Australia, the U.S., Mexico, and other parts of Europe and the Americas. Some of the apps are listed below –

• Essential Horoscope for Android (com.anomenforyou.essentialhoroscope)
• 3D Skin Editor for PE Minecraft (com.littleray.skineditorforpeminecraft)
• Logo Maker Pro (com.vyblystudio.dotslinkpuzzles)
• Auto Click Repeater (com.autoclickrepeater.free)
• Count Easy Calorie Calculator (com.lakhinstudio.counteasycaloriecalculator)
• Sound Volume Extender (com.muranogames.easyworkoutsathome)
• LetterLink (com.regaliusgames.llinkgame)
• NUMEROLOGY: PERSONAL HOROSCOPE &NUMBER PREDICTIONS (com.Ushak.NPHOROSCOPENUMBER)
• Step Keeper: Easy Pedometer (com.browgames.stepkeepereasymeter)
• Track Your Sleep (com.shvetsStudio.trackYourSleep)
• Sound Volume Booster (com.devapps.soundvolumebooster)
• Astrological Navigator: Daily Horoscope & Tarot (com.Osinko.HoroscopeTaro)
• Universal Calculator (com.Potap64.universalcalculator)

Xamalicious, which typically masquerades as health, games, horoscope, and productivity apps, is the latest in a long list of malware families that abuse Android’s accessibility services, requesting users’ access to it upon installation to carry out its tasks.

“To evade analysis and detection, malware authors encrypted all communication and data transmitted between the C2 and the infected device, not only protected by HTTPS, it’s encrypted as a JSON Web Encryption (JWE) token using RSA-OAEP with a 128CBC-HS256 algorithm,” Ruiz noted.

Even more troublingly, the first-stage dropper contains functions to self-update the main Android package (APK) file, meaning it can be weaponized to act as spyware or banking trojan without any user interaction.

McAfee said it identified a link between Xamalicious and an ad-fraud app named Cash Magnet, which facilitates app download and automated clicker activity to illicitly earn revenue by clicking on ads.

“Android applications written in non-java code with frameworks such as Flutter, react native and Xamarin can provide an additional layer of obfuscation to malware authors that intentionally pick these tools to avoid detection and try to stay under the radar of security vendors and keep their presence on apps markets,” Ruiz said.

Android Phishing Campaign Targets India With Banker Malware

The disclosure comes as the cybersecurity company detailed a phishing campaign that employs social messaging apps like WhatsApp to distribute rogue APK files that impersonate legitimate banks such as the State Bank of India (SBI) and prompt the user to install them to complete a mandatory Know Your Customer (KYC) procedure.

Once installed, the app asks the user to grant it SMS-related permissions and redirects to a fake page that only captures the victim’s credentials but also their account, credit/debit card, and national identity information.

The harvested data, alongside the intercepted SMS messages, are forwarded to an actor-controlled server, thereby allowing the adversary to complete unauthorized transactions.

It’s worth noting that Microsoft last month warned of a similar campaign that utilizes WhatsApp and Telegram as distribution vectors to target Indian online banking users.

“India underscores the acute threat posed by this banking malware within the country’s digital landscape, with a few hits found elsewhere in the world, possibly from Indian SBI users living in other countries,” researchers Neil Tyagi and Ruiz said.