Monday, July 22, 2024

Beware Of Fake Microsoft Teams Website That Installs Oyster Malware

Fake websites of authoritative and popular companies claiming to be genuine sites make users believe that the site belongs to that specific company and is safe to use.

Besides this, hackers can more easily lure victims into entering sensitive information or downloading malware by mimicking popular and reputable brands.

Cybersecurity researchers at Rapid 7 identified a fresh malvertising campaign that deceives users into downloading malicious installers pretending to be well-known utilities, such as Google Chrome and Microsoft Teams.

These installers deliver a backdoor named “Oyster” or “Broomstick.” Following its establishment, hands-on keyboard activity involves system enumeration and deployment of other malicious payloads.

Scan Your Business Email Inbox to Find Advanced Email Threats - Try AI-Powered Free Threat Scan

Beware Of Fake Microsoft Teams Website

When they looked for the software on the Web, users downloaded Microsoft Teams installers from typosquatted websites in three instances.

These were rogue sites posing as authentic Microsoft ones and led trustful users to download malware instead of genuine software applications.

Fake Website

For one, “micrsoft-teams-download[.]com” sent binary MSTeamsSetup_c_l_.exe signed with a certificate issued for Shanxi Yanghua HOME Furnishings Ltd, likely used maliciously to look like a legitimate entity on VirusTotal.

In May 2024, legitimate software was impersonated by multiple installers, one of which employed a Microsoft Teams setup file with a revoked certificate.

The Rapid 7 report states that the Oyster (aka Broomstick, CleanUpLoader) malware family was first distributed via this installer in September 2023.

System data is collected while hardcoded C2s are contacted, consequently making it possible to execute remote code. The recent sample drops CleanUp30.dll, which creates a scheduled task that allows the virus to be launched every 3 hours when it runs itself again.

The C2 domains get decoded using a byte mapping algorithm, and fingerprint machines are infected, which helps send back such information to the C2 infrastructure.

Here below, we have mentioned all the functions that are used to fingerprint the infected machine:-

  • DsRoleGetPrimaryDomainInformation
  • GetUserNameW
  • NetUserGetInfo
  • GetComputerNameW
  • RtlGetVersion

While enumerating host information, the data is stored in JSON fields from decoded strings. 

The fingerprint is encoded by reversing and byte mapping the string before sending via HTTP POST to whereverhomebe[.]com/, supfoundrysettlers[.]us/, and retdirectyourman[.]eu/. 

CleanUp30.dll uses Boost.Beast for HTTP/WebSocket C2 communication. After executing CleanUp30.dll, a PowerShell script spawned, creating a startup shortcut DiskCleanUp.lnk to run CleanUp.dll via rundll32.exe. 

This executed the k1.ps1, main.dll, and getresult.exe payloads.

Free Webinar! 3 Security Trends to Maximize MSP Growth -> Register For Free


Latest articles

SonicOS IPSec VPN Vulnerability Let Attackers Cause Dos Condition

SonicWall has disclosed a critical heap-based buffer overflow vulnerability in its SonicOS IPSec VPN....

Hackers Registered 500k+ Domains Using Algorithms For Extensive Cyber Attack

Hackers often register new domains for phishing attacks, spreading malware, and other deceitful activities. Such...

Hackers Claim Breach of Daikin: 40 GB of Confidential Data Exposed

Daikin, the world's largest air conditioner manufacturer, has become the latest target of the...

Emojis Are To Express Emotions, But CyberCriminals For Attacks

There are 3,664 emojis that can be used to express emotions, ideas, or objects...

Beware Of Fake Browser Updates That Installs Malicious BOINC Infrastructre

SocGholish malware, also known as FakeUpdates, has exhibited new behavior since July 4th, 2024,...

Data Breach Increases by Over 1,000% Annually

The Identity Theft Resource Center® (ITRC), a nationally recognized nonprofit organization established to support...

UK Police Arrested 17-year-old Boy Responsible for MGM Resorts Hack

UK police have arrested a 17-year-old boy from Walsall in connection with a notorious...
Tushar Subhra Dutta
Tushar Subhra Dutta
Tushar is a Cyber security content editor with a passion for creating captivating and informative content. With years of experience under his belt in Cyber Security, he is covering Cyber Security News, technology and other news.

Free Webinar

Low Rate DDoS Attack

9 of 10 sites on the AppTrana network have faced a DDoS attack in the last 30 days.
Some DDoS attacks could readily be blocked by rate-limiting, IP reputation checks and other basic mitigation methods.
More than 50% of the DDoS attacks are employing botnets to send slow DDoS attacks where millions of IPs are being employed to send one or two requests per minute..
Key takeaways include:

  • The mechanics of a low-DDoS attack
  • Fundamentals of behavioural AI and rate-limiting
  • Surgical mitigation actions to minimize false positives
  • Role of managed services in DDoS monitoring

Related Articles