Cybercriminals are increasingly targeting Microsoft Teams, utilizing the platform for sophisticated phishing, vishing, and ransomware campaigns. Exploiting Teams' widespread use, attackers employ social engineering tactics to deceive users and extract sensitive data. Methods range from fake job offers to malicious file sharing, aiming to infiltrate accounts and compromise organizational networks.
Bypassing Multifactor Authentication
One notable tactic involves bypassing multifactor authentication (MFA). Threat actors, reportedly linked to the SolarWinds attack, create fraudulent “onmicrosoft.com” subdomains designed to mimic legitimate security entities. They send chat requests via Microsoft Teams, prompting users to enter a code into the Microsoft Authenticator app. This action grants attackers unauthorized access to Microsoft 365 accounts, enabling data theft or the integration of malicious devices into corporate networks.
The Black Basta ransomware group employs a different strategy by overwhelming users with spam emails and impersonating IT support staff on Teams. Claiming to assist with email issues, they persuade victims to install remote desktop tools, providing attackers with direct access to deploy malware. This includes Trojans and ransomware designed to exfiltrate sensitive data and compromise systems.
Another prevalent scheme involves fake job offers. Scammers contact individuals with fabricated employment opportunities, sometimes conducting entire interviews via Microsoft Teams chat. These scams often escalate to requests for personal information, such as Social Security numbers or tax details. In some cases, victims are asked to pay for materials or services, resulting in financial loss and potential identity theft.
Attackers also impersonate HR personnel, sending phishing messages about urgent policy updates. These messages frequently include malicious files disguised as legitimate updates. Once downloaded, malware like DarkGate is installed, granting attackers control over the victim’s system and network.
Additionally, compromised Microsoft 365 accounts are used to distribute malicious files through Teams chats. These files often appear as PDFs with double extensions, deceiving users into downloading executable malware. Once activated, these programs can breach data and facilitate deeper network infiltration.
Mitigation Strategies for Organizations and Users
Vigilance is essential in countering these threats. Users should verify unexpected messages, invitations, or file-sharing requests, especially those containing links or urgent calls to action. Tools that check link safety and domain age can help detect phishing attempts.
Organizations should prioritize employee education on recognizing scams and enforcing robust cybersecurity protocols. By staying informed and cautious, users can mitigate risks and safeguard against cyberattacks targeting Microsoft Teams.
