August 2, 2021

Malware Protection

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MosaicLoader malware targets cracked software via SEO poisoning

New MosaicLoader malware targets users that are searching to download cracked software. Cybercriminals run ad campaigns in search engine results to boost their malicious links when users search for terms related to that Cracked Software.

Cybersecurity researchers From Bitdefender on Tuesday published research on a previously undocumented malware strain dubbed “MosaicLoader” that singles out individuals searching for cracked software as part of a global campaign.

MosaicLoader is a malware downloader designed by its creators to deploy more second-stage payloads on infected systems.

“The malware arrives on target systems by posing as cracked installers. It downloads a malware sprayer that obtains a list of URLs from the C2 server and downloads the payloads from the received links.”

“We named it MosaicLoader because of the intricate internal structure that aims to confuse malware analysts and prevent reverse-engineering,” Janos Gergo Szeles, Senior Security Researcher at Bitdefender.

Once planted on the system, the malware creates a complex chain of processes and tries to download a variety of threats, from simple cookie stealers, crypto-currency miners to fully-fledged backdoors such as Glupteba.

During their investigation, Bitdefender found that MosaicLoader threat actors used the following tactics to hinder researchers’ malware analysis efforts and to increase their attacks’ rate of success:

  • Mimicking file information that is similar to legitimate software
  • Code obfuscation with small chunks and shuffled execution order
  • Payload delivery mechanism infecting the victim with several malware strains

Exclusion of windows defender via Powershell

Interestingly, Windows Defender exclusion can be found in the registry keys below.

  • File and folder exclusions – HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows DefenderExclusionsPaths
  • File type exclusions – HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows DefenderExclusionsExtensions
  • Process exclusions – HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows DefenderExclusionsProcesses

The researcher added that the campaign doesn’t target a specific region. Due to online advertising, it will attempt to infect any search engine users looking to download and install cracked software installers on their devices.

The stolen info can later be used to hijack victims’ online accounts and use the gained access in identity theft scams or blackmail scams.

Given MosaicLoader’s wide-ranging capabilities, compromised systems can be co-opted into a botnet that the threat actor can then exploit to propagate multiple and evolving sets of sophisticated malware, including both publicly available and customized malware, to obtain, expand, and maintain unauthorized access to victim computers and networks.

“Besides being against the law, cybercriminals look to target and exploit users searching for illegal and Cracked software.”

Recommendations to Defend Yourself

Mosaic predominantly targets victims looking for cracked software – we advise users that they do not download and install applications from untrusted websites.

Businesses should apply the IOCs to their EDR systems to ensure that employees working from home (who are at higher risk for downloading cracked software) are not impacted.