Apr 08, 2024NewsroomCybersecurity / Malvertising

A new phishing campaign has set its eyes on the Latin American region to deliver malicious payloads to Windows systems.

“The phishing email contained a ZIP file attachment that when extracted reveals an HTML file that leads to a malicious file download posing as an invoice,” Trustwave SpiderLabs researcher Karla Agregado said.

The email message, the company said, originates from an email address format that uses the domain “temporary[.]link” and has Roundcube Webmail listed as the User-Agent string.

The HTML file points containing a link (“facturasmex[.]cloud”) that displays an error message saying “this account has been suspended,” but when visited from an IP address geolocated to Mexico, loads a CAPTCHA verification page that uses Cloudflare Turnstile.

This step paves the way for a redirect to another domain from where a malicious RAR file is downloaded. The RAR archive comes with a PowerShell script that gathers system metadata as well as checks for the presence of antivirus software in the compromised machine.

It also incorporates several Base64-encoded strings that are designed to run PHP scripts to determine the user’s country and retrieve a ZIP file from Dropbox containing “many highly suspicious files.”

Trustwave said the campaign exhibits similarities with that of Horabot malware campaigns that have targeted Spanish-speaking users in Latin America in the past.

“Understandably, from the threat actors’ point of view, phishing campaigns always try different [approaches] to hide any malicious activity and avoid immediate detection,” Agregado said.

“Using newly created domains and making them accessible only in specific countries is another evasion technique. especially if the domain behaves differently depending on their target country.”

The development comes as Malwarebytes revealed a malvertising campaign targeting Microsoft Bing search users with bogus ads for NordVPN that lead to the distribution of a remote access trojan called SectopRAT (aka ArechClient) hosted on Dropbox via a phony website (“besthord-vpn[.]com”).

“Malvertising continues to show how easy it is to surreptitiously install malware under the guise of popular software downloads,” security researcher Jérôme Segura said. “Threat actors are able to roll out infrastructure quickly and easily to bypass many content filters.”

It also follows the discovery of a fake Java Access Bridge installer that serves as a conduit to deploy the open-source XMRig cryptocurrency miner, per SonicWall.

The network security company said it also discovered a Golang malware that “uses multiple geographic checks and publicly available packages to screenshot the system before installing a root certificate to the Windows registry for HTTPS communications to the [command-and-control server].”

Mar 14, 2024NewsroomCyber Threat / Malware

The threat actor known as Blind Eagle has been observed using a loader malware called Ande Loader to deliver remote access trojans (RATs) like Remcos RAT and NjRAT.

The attacks, which take the form of phishing emails, targeted Spanish-speaking users in the manufacturing industry based in North America, eSentire said.

Blind Eagle (aka APT-C-36) is a financially motivated threat actor that has a history of orchestrating cyber attacks against entities in Colombia and Ecuador to deliver an assortment of RATs, including AsyncRAT, BitRAT, Lime RAT, NjRAT, Remcos RAT, and Quasar RAT.

The latest findings mark an expansion of the threat actor’s targeting footprint, while also leveraging phishing bearing RAR and BZ2 archives to activate the infection chain.

The password-protected RAR archives come with a malicious Visual Basic Script (VBScript) file that’s responsible for establishing persistence in the Windows Startup folder and launching the Ande Loader, which, in turn, loads the Remcos RAT payload.

In an alternative attack sequence observed by the Canadian cybersecurity firm, a BZ2 archive containing a VBScript file is distributed via a Discord content delivery network (CDN) link. The Ande Loader malware, in this case, drops NjRAT instead of Remcos RAT.

“Blind Eagle threat actor(s) have been using crypters written by Roda and Pjoao1578,” eSentire said. “One of the crypters developed by Roda has the hardcoded server hosting both injector components of the crypter and additional malware that was used in the Blind Eagle campaign.”

The development comes as SonicWall shed light on the inner workings of another loader malware family called DBatLoader, detailing its use of a legitimate-but-vulnerable driver associated with RogueKiller AntiMalware software (truesight.sys) to terminate security software as part of a Bring Your Own Vulnerable Driver (BYOVD) attack and ultimately deliver Remcos RAT.

“The malware is received inside an archive as an email attachment and is highly obfuscated, containing multiple layers of encryption data,” the company noted earlier this month.

Cybersecurity researchers are warning about a spike in email phishing campaigns that are weaponizing the Google Cloud Run service to deliver various banking trojans such as Astaroth (aka Guildma), Mekotio, and Ousaban (aka Javali) to targets across Latin America (LATAM) and Europe.

“The infection chains associated with these malware families feature the use of malicious Microsoft Installers (MSIs) that function as droppers or downloaders for the final malware payload(s),” Cisco Talos researchers disclosed last week.

The high-volume malware distribution campaigns, observed since September 2023, have employed the same storage bucket within Google Cloud for propagation, suggesting potential links between the threat actors behind the distribution campaigns.

Google Cloud Run is a managed compute platform that enables users to run frontend and backend services, batch jobs, deploy websites and applications, and queue processing workloads without having to manage or scale the infrastructure.

“Adversaries may view Google Cloud Run as an inexpensive, yet effective way to deploy distribution infrastructure on platforms that most organizations likely do not prevent internal systems from accessing,” the researchers said.

A majority of the systems used to send phishing messages originate from Brazil, followed by the U.S., Russia, Mexico, Argentina, Ecuador, South Africa, France, Spain, and Bangladesh. The emails bear themes related to invoices or financial and tax documents, in some cases purporting to be from local government tax agencies.

Embedded within these messages are links to a website hosted on run[.]app, resulting in the delivery of a ZIP archive containing a malicious MSI file either directly or via 302 redirects to a Google Cloud Storage location, where the installer is stored.

The threat actors have also been observed attempting to evade detection using geofencing tricks by redirecting visitors to these URLs to a legitimate site like Google when accessing them with a U.S. IP address.

Besides leveraging the same infrastructure to deliver both Mekotio and Astaroth, the infection chain associated with the latter acts as a conduit to distribute Ousaban.

Astaroth, Mekotio, and Ousaban are all designed to single out financial institutions, keeping tabs on users’ web browsing activity as well as logging keystrokes and taking screenshots should one of the target bank websites be open.

Ousaban has a history of weaponizing cloud services to its advantage, having previously employed Amazon S3 and Microsoft Azure to download second-stage payloads, and Google Docs to retrieve command-and-control (C2) configuration.

The development comes amid phishing campaigns propagating malware families such as DCRat, Remcos RAT, and DarkVNC that are capable of harvesting sensitive data and taking control of compromised hosts.

It also follows an uptick in threat actors deploying QR codes in phishing and email-based attacks (aka quishing) to trick potential victims into installing malware on their mobile devices.

“In a separate attack, the adversaries sent targets spear-phishing emails with malicious QR codes pointing to fake Microsoft Office 365 login pages that eventually steal the user’s login credentials when entered,” Talos said.

“QR code attacks are particularly dangerous because they move the attack vector off a protected computer and onto the target’s personal mobile device, which usually has fewer security protections in place and ultimately has the sensitive information that attackers are after.”

Phishing campaigns have also set their eyes on the oil and gas sector to deploy an information stealer called Rhadamanthys, which has currently reached version 0.6.0, highlighting a steady stream of patches and updates by its developers.

“The campaign starts with a phishing email using a vehicle incident report to lure victims into interacting with an embedded link that abuses an open redirect on a legitimate domain, primarily Google Maps or Google Images,” Cofense said.

Users who click on the link are then redirected to a website hosting a bogus PDF file, which, in reality, is a clickable image that contacts a GitHub repository and downloads a ZIP archive containing the stealer executable.

“Once a victim attempts to interact with the executable, the malware will unpack and start a connection with a command-and-control (C2) location that collects any stolen credentials, cryptocurrency wallets, or other sensitive information,” the company added.

Other campaigns have abused email marketing tools like Twilio’s SendGrid to obtain client mailing lists and take advantage of stolen credentials to send out convincing-looking phishing emails, per Kaspersky.

“What makes this campaign particularly insidious is that the phishing emails bypass traditional security measures,” the Russian cybersecurity company noted. “Since they are sent through a legitimate service and contain no obvious signs of phishing, they may evade detection by automatic filters.”

These phishing activities are further fueled by the easy availability of phishing kits such as Greatness and Tycoon, which have become a cost-effective and scalable means for aspiring cyber criminals to mount malicious campaigns.

“Tycoon Group [phishing-as-a-service] is sold and marketed on Telegram for as low as $120,” Trustwave SpiderLabs researcher Rodel Mendrez said last week, noting the service first came into being around August 2023.

“Its key selling features include the ability to bypass Microsoft two-factor authentication, achieve ‘link speed at the highest level,’ and leveraging Cloudflare to evade antibot measures, ensuring the persistence of undetected phishing links.”