Phishing is most commonly associated with email; however, there are a variety of ways that cybercriminals can make contact with end users and other forms of phishing are becoming much more common. Smishing is the use of SMS messages for phishing which targets users via their smartphones, which tend to have far weaker security controls than laptops and PCs. Voice phishing is also common, where malicious actors trick people into disclosing sensitive information or installing malware over the phone. Phishing can also take place via social media networks and video conferencing platforms such as Microsoft Teams.

A campaign has recently been identified that uses Microsoft Teams group chat requests for phishing. A threat actor appears to be using a compromised account to send Teams group chat invites to thousands of individuals. The compromised User’s Teams account is likely to have been compromised in a phishing, credential stuffing, or brute force attack. This campaign aims to install malware on users’ systems – a malware variant called DarkGate. DarkGate malware was first identified in 2018 and is a remote access Trojan that can install a hidden virtual network computing (hVNC) module to provide remote access to a victim’s device. The malware has keylogging and information-stealing capabilities and can steal cookies and information stored in browsers, Discord tokens, and cryptocurrency wallets. The malware can also download other payloads such as ransomware.

In this campaign, if a user accepts the group chat request, the threat actor uses social engineering techniques to trick them into downloading a file to their device. The user is tricked into thinking that they are downloading a PDF file, but they download an executable file. The file – Navigating Future Changes October 2023.pdf.msi – has a double extension. On Windows systems, which are typically configured to hide known file extensions, the file will be displayed as Navigating Future Changes October 2023.pdf. If the user double-clicks on the file, the malware will be installed and will connect to its command-and-control server, giving the treat actor control over the user’s device.

Microsoft Teams has become a popular target for threat actors for malware distribution. There are around 280 million monthly users, and the default settings allow Microsoft Teams users to receive chat requests from external Microsoft Teams users. While most users will have antivirus software on their devices for detecting malware, DarkGate malware is stealthy and often evades antivirus software. There are several steps that businesses can take to combat these attacks. The most important of which is to disable External Access in Microsoft Teams unless it is absolutely necessary for day-to-day business use. This will ensure that users can only receive chat requests internally, which will greatly reduce risk.

Another important measure is to provide regular security awareness training to the workforce. Employees should be taught cybersecurity basics such as how to recognize a phishing attempt and should be made aware of the latest tactics used by cybercriminals in attacks on employees. Training should be provided continuously, with short training sessions conducted every month. When new phishing techniques are identified, short training modules can be pushed out to employees to make them aware of the threat. With the SafeTitan security awareness training platform this is easy. The platform has a wide range of CBT content, with training modules lasting no more than 10 minutes so they are easy to fit in to workflows.

If you do not currently provide regular security awareness training to your workforce, contact TitanHQ about SafeTitan. Product demonstrations can be arranged on request, and you can test the product for yourself in a free trial.