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A brand new model of a banking trojan often known as Mekotio is being deployed within the wild, with malware analysts reporting that it is utilizing a brand new, stealthier an infection move.
The final notable exercise of Mekotio dates again to the summer season of 2020 when the trojan’s operators deployed it in a marketing campaign focusing on Latin American international locations.
The focusing on scope seems to be the identical in current assaults, with Spanish being the language of selection for the phishing emails that begin the an infection chain.
A brand new assault move
The an infection begins with a phishing electronic mail bundling a ZIP attachment containing an obfuscated batch script that fetches and executes a PowerShell script.
As soon as the PowerShell script will get launched, it is going to obtain a second ZIP archive after some fundamental location and anti-analysis checks.
If the checks verify the sufferer is in Latin America and the malware is not operating on a digital machine, the second ZIP, which incorporates the Mekotio payload in DLL kind, is extracted.
New Mekotio assault move diagramSource: CheckPoint
Multi-step assault flows just like the one above could seem unnecessarily difficult, however they’re wanted to evade detection and efficiently deploy the ultimate payload.
One of many benefits of modular assaults is the added potential to make refined adjustments that render earlier detection strategies ineffective.
That is exactly the case in Mekotio’s growth, because the trojan’s code has largely remained unchanged, with its authors principally tweaking issues as a substitute of including new capabilities.
Phishing electronic mail utilized in current Mekotio campaignSource: CheckPoint
Usual code in new wrapping
The three novel parts that make the newest Mekotio model tougher to detect are the next:
A stealthier batch file with at the very least two layers of obfuscation
New file-less PowerShell script that runs straight in reminiscence
Use of Themida v3 for packing the ultimate DLL payload
CheckPoint stories seeing roughly 100 assaults previously three months deploying cipher substitution strategies, which albeit easy, assist Mekotio go undetected by most AV merchandise.
The second layer of obfuscation is slicing the PowerShell instructions into elements saved in several surroundings variables after which concatenating the values throughout execution.
Second layer of obfuscation on the PowerShell scriptSource: CheckPoint
The trojan’s major objective stays to steal individuals’s e-banking credentials and on-line account passwords.
Some previous Mekotio variants may additionally hijack cryptocurrency funds and direct them to actor-controlled wallets, however current variations have eliminated this performance.
CheckPoint says the brand new marketing campaign was launched proper after the Spanish Civil Guard arrested 16 individuals in Mexico, linked with native Mekotio distribution.
Nonetheless, the core Mekotio crew seems to be primarily based in Brazil, and it is assumed that they’re Mekotio’s creators who are actually promoting it to different cybercriminals.
ESET characterised this explicit trojan as “chaotic” final yr as a result of concurrent growth that resulted within the simultaneous circulation of various variants.
That exercise has now waned, and the newest marketing campaign makes use of the variant analyzed by CheckPoint.
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