Threat actors behind the Mispadu banking trojan have become the latest to exploit a now-patched Windows SmartScreen security bypass flaw to compromise users in Mexico.
The attacks involve a new variant of malware first observed in 2019, Palo Alto Networks’ Unit 42 said in a report published last week.
Propagated via phishing emails, Mispadu is a Delphi-based information stealer known to specifically infect victims in the Latin America (LATAM) region. In March 2023, Metabase Q revealed that Mispadu spam campaigns have collected no fewer than 90,000 bank account credentials since August 2022.
It is also part of Latin America’s larger family of banking malware, including Grandoreiro, which was dismantled by Brazilian law enforcement last week.
The latest infection chain identified by Unit 42 uses rogue Internet shortcut files contained in bogus ZIP archive files that exploit CVE-2023-36025 (CVSS score: 8.8), a high-severity bypass flaw in Windows SmartScreen. It was fixed by Microsoft in November 2023.
“This exploit revolves around the creation of a specially crafted Internet link (.URL) file or hyperlink that points to malicious files that can bypass SmartScreen warnings,” said security researchers Daniela Shalev and Josh Grunzweig .
“The bypass is simple and relies on a parameter that references a network share, rather than a URL. The created .URL file contains a link to a threat actor’s network share with a malicious binary code.”
Mispadu, once launched, reveals its true nature by selectively targeting victims based on their geographic location (e.g., Americas or Western Europe) and system configurations, then proceeds to establish contact with a command server and control (C2) for follow-up. on data exfiltration.
In recent months, the Windows flaw has been wildly exploited by several cybercrime groups to spread DarkGate and Phemedrone Stealer malware.
Mexico has also emerged as a prime target of several campaigns over the past year that have proven to propagate information theft and remote access Trojans such as AllaKore RAT, AsyncRAT, Babylon RAT. This is a financially motivated group called TA558 that has been attacking the hospitality and travel sectors in the LATAM region since 2018.
The development comes as Sekoia details the inner workings of DICELOADER (also known as Lizar or Tirion), a time-tested custom downloader used by the Russian electronic crime group identified as FIN7. Malware has been observed to be distributed via malicious USB drives (also known as BadUSB) in the past.
“DICELOADER is dropped by a PowerShell script along with other malware from the intrusion set arsenal such as Carbanak RAT,” the French cybersecurity firm said, highlighting its sophisticated obfuscation methods to hide C2 IP addresses and communications of network.
It also follows AhnLab’s discovery of two new malicious cryptocurrency mining campaigns that use booby-trapped archives and game hacks to distribute malware to miners mining Monero and Zephyr.