A recent phishing campaign delivering fake Office 365 password expiration reports has managed to compromise several C-Suite email accounts, according to a warning from anti-malware vendor Trend Micro.
Threat actors involved in the scam targeted organisations in sectors as diverse as finance, government, manufacturing, real estate, and technology, with victims spread over Japan, the United States, U.K., Canada, Australia, and several European countries.
More than 300 unique compromised URLs have been identified to date, along with 70 e-mail addresses from 8 different websites. The phishers involved were able to compromise 40 legitimate email addresses of CEOs, directors, company founders, and owners, as well as those of other employees.
The reasonably sophisticated attack saw the attackers use fake Office 365 password expiration reports as lures, requesting victims click on an embedded link that would allow them to continue “using the same password”. However, once the victim clicks on the “Keep Password” option, they are taken to the phishing page.
Compromised infrastructure and stolen credentials were abused to host phishing pages and target more victims.
The hackers involved used a phishing kit that was first discovered last year, when used in similar attacks leveraging fake Microsoft login pages. Available for purchase, the kit allows cybercriminals to validate stolen credentials.
Trend Micro also discovered that cybercriminals are advertising stolen credentials for Office 365 accounts of CEOs, chief financial officers (CFOs), and employees in the finance department, among others.
Most of the phishing emails in this campaign were sent using a virtual private server (VPS) from FireVPS, a firm that provides customers with various Windows remote desktop protocol (RDP) plans.
Trend Micro says they alerted the company of its service being abused in the phishing campaign.
The phishing kit, which appears to be the evolution of similar toolkits, also includes an extensive list of IP address ranges and domain names, aiming to block access for security companies and large cloud providers, likely in an attempt to evade detection.
The phishing kit’s developer is actively advertising the creation on social media sites and is engaged in the selling of stolen credentials. Trend Micro was eventually able to link the developer’s business Facebook page with the personal one, and has already provided authorities with details on the issue.
The email addresses of CEOs in the United States are understood to be the main target of this campaign and others using the same phishing kit. They in turn allow attackers to conduct further phishing, compromise sensitive information, and conduct business email compromise (BEC) and other social engineering attacks.