A recent report by Kaspersky suggests the latest version of Necro Trojan was deployed via infected advertising software development kits (SDK) used by Android game mods, authentic apps, and mod variants of famous software, such as Minecraft, Spotify, and WhatsApp. The blog covers key findings from the Kaspersky report, the techniques used by threat actors, and the impact on cybersecurity.
What is Necro Trojan
Aka Necro Python, the Necro Trojan is an advanced malware strain active since it first appeared. Malware can perform various malicious activities such as cryptocurrency mining, data theft, and installation of additional payloads. The recent version is more advanced, making it difficult to track and eliminate.
Distribution of Necro Trojan
Users sometimes want premium or customized options that official versions don't have. But these unofficial mods, such as GB WhatsApp, Spotify+, and Insta Pro can contain malware. Traditionally, threat actors used these mods because they are distributed on unofficial sites that lack moderation.
However, in the recent trend, experts discovered actors targeting official app stores via infected apps.
In the latest case, Trojan authors abused both distribution vectors, a new variant of multi-stage Necro loader compromised modified versions of Spotify, Minecraft, and other famous apps in unofficial sources, and apps in Google Play. "The modular architecture gives the Trojan’s creators a wide range of options for both mass and targeted delivery of loader updates or new malicious modules depending on the infected application,” said the report.
Key Findings
- The downloaded payloads can display ads in invisible windows, and interact with them. They can also execute arbitrary DEX files, install download apps, open arbitrary links in invisible WebView windows and run JavaScript, run a tunnel via the victim's device, and subscribe to paid services.
- The new variant of the Necro loader uses obfuscation to escape detection.
- The loader deployed in the app uses steganography tactics to hide payloads