A new packer-as-a-service (PaaS) called HeartCrypt has emerged, offering malware operators a powerful tool for evading antivirus detection. Developed in July 2023 and launched in February 2024, HeartCrypt quickly gained popularity in the cybercrime underground, with over 2,000 malicious payloads packed across 45 different malware families. The service is advertised on underground forums and Telegram channels, offering a cost-effective method of packing malware for just $20 per file. It primarily caters to operators using well-known malware families like LummaStealer, Remcos, and Rhadamanthys.
HeartCrypt operates by injecting malicious code into legitimate executable files, a technique that makes it difficult for antivirus software to detect the malware. The packing process involves injecting code into over 300 distinct legitimate binaries, which disguises the malware as a harmless program at first glance. Once executed, HeartCrypt’s payload is encrypted using a single-byte XOR operation and is decrypted either through process hollowing or by leveraging the .NET framework. This advanced obfuscation ensures that the malicious code is hidden from traditional security mechanisms.
In addition to its packing technique, HeartCrypt employs multiple anti-analysis strategies. These include loading non-existent DLLs to detect sandbox environments, using complex calculations to bypass loop emulation, and leveraging virtual DLLs to evade detection by Windows Defender’s emulator. By modifying the control flow of the original binary and using position-independent code (PIC), HeartCrypt ensures that the malware operates regardless of its memory location, further complicating efforts to detect and analyze it. The obfuscation also involves techniques like stack strings, dynamic API resolution, and the use of unnecessary arithmetic operations to confuse analysts.
The emergence of HeartCrypt as a PaaS lowers the barrier to entry for cybercriminals, increasing the volume and success rate of malware infections. This development highlights the growing sophistication of malware and the continuous challenges faced by cybersecurity professionals. As HeartCrypt evolves, security researchers have already begun analyzing its payloads, providing valuable insights into its operations. Organizations must remain vigilant and ensure their security measures are up-to-date to defend against such emerging threats.
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