Kaspersky reports a spike in phishing emails containing malicious QR codes. Detections for these jumped from 46,969 in August to 249,723 in November – a more than fivefold growth – as cybercriminals increasingly exploit QR codes. Attackers use QR codes in emails more frequently because they provide a simple and cost-effective way to conceal malicious URLs, evading detection by many protective solutions.

The number of blocked phishing emails with malicious QR code links

These QR codes are often embedded directly in email bodies or, even more commonly, within PDF attachments – an evolution that both masks phishing links and encourages users to scan them on mobile phones, which may have weaker security than work PCs.

Example of a PDF attachment with a QR code

Malicious QR codes commonly appear in mass phishing campaigns as well as targeted ones. Links embedded within them may lead to:

• Phishing forms impersonating login pages for services like Microsoft accounts or internal corporate portals, designed to steal usernames, passwords, and other credentials.
• Fake HR notifications urging employees to review or sign documents, such as vacation schedules, or even view lists of terminated staff, ultimately directing to credential-stealing sites.
• Fraudulent invoices or purchase confirmations in PDF attachments, often combined with vishing (voice phishing) tactics that prompt victims to call provided phone numbers to “cancel” or clarify the transaction, enabling further social engineering attacks.

These tactics exploit trust in routine business communications, leading to credential theft, account takeovers, data breaches, and financial fraud.

“Malicious QR codes have evolved into one of the most effective phishing tools this year, particularly when hidden in PDF attachments or disguised as legitimate business communications like HR updates. The explosive growth in November highlights how attackers are capitalizing on this low-cost evasion technique to target employees on mobile devices, where protection is often minimal. Without advanced image analysis at the email gateway and safe scanning practices, organizations are left vulnerable to credential compromise and downstream breaches,” comments Roman Dedenok, Anti-Spam Expert at Kaspersky.

To defend against this escalating threat, Kaspersky recommends deploying a mail server security solution such as Kaspersky Security for Mail Server that provides trusted and secure corporate email exchange, countering spam, email-borne infections, all forms of phishing, business email compromise (BEC), QR code attacks, and other threats.