Beware of Ongoing Phishing Campaign Targeting Zimbra Collaboration Servers


In recent months, an alarming cybersecurity threat has emerged, targeting Zimbra Collaboration email servers worldwide. This phishing campaign, which began in April 2023, has set its sights on stealing valuable credentials from organizations using Zimbra Collaboration Suite. In this article, we’ll take a closer look at this ongoing campaign, its tactics, and how businesses can protect themselves.

The Unseen Threat: A Global Campaign

According to a comprehensive report by a software-based cybersecurity company, the attackers behind this campaign have cast a wide net, sending phishing emails to organizations across the globe. Unlike many cyberattacks that focus on specific sectors or high-profile targets, this campaign appears to have no discrimination in its choice of victims. What’s particularly concerning is that the identity of the threat actor remains shrouded in mystery.

The Phishing Ploy: Impersonating Zimbra Admins

The attackers employ a cunning strategy that begins with a phishing email, cleverly disguised as a communication from the organization’s admin. The email informs recipients of an upcoming email server update, warning that it will lead to temporary account deactivation. To learn more and prevent this, recipients are instructed to open an attached HTML file.

Upon opening the HTML attachment, victims are presented with a deceptive Zimbra login page. This fake page includes the targeted company’s logo and branding elements to create an appearance of authenticity. Moreover, the username field is pre-filled, adding an extra layer of credibility to the phishing attempt.

Data Theft in Motion: Stolen Credentials

Unbeknownst to the victims, any account credentials entered into this phishing form are swiftly transmitted to the attacker’s server via an HTTPS POST request. This clandestine data exfiltration puts organizations at risk of unauthorized access to their sensitive information and resources.

A Remarkable Yet Worrying Success

Despite its relatively unsophisticated nature, this phishing campaign has achieved remarkable success in terms of its reach and impact. The threat is real and substantial, making it imperative for all users of Zimbra to be vigilant and proactive in defending against such threats.

Why Zimbra?

Zimbra Collaboration email servers have increasingly become a prime target for cybercriminals. Hackers often use these servers for cyber espionage, aiming to gather valuable internal communications or gain an initial foothold within an organization’s network, for further attacks in the future. Notably, earlier this year, the ‘Winter Vivern’ hacking group exploited a Zimbra Collaboration flaw to breach NATO-aligned organizations, governments, diplomats, and military personnel.

Last year, ‘TEMP_Heretic’ leveraged a zero-day flaw in Zimbra Collaboration to access mailboxes and carry out lateral phishing attacks. ESET concludes that Zimbra Collaboration’s popularity among organizations with constrained IT budgets makes it an attractive target for adversaries.

Stay Vigilant and Protected

In this era of persistent cyber threats, safeguarding your organization’s data and infrastructure is paramount. The ongoing Zimbra Collaboration phishing campaign serves as a stark reminder that vigilance and robust cybersecurity measures are essential.

We want to help you stay safe

Zimbra mailboxes by Logix are secured with built-in email advanced threat protection that works efficiently to keep email threats at bay.

Continue to chat
Hello 👋
Let us know how we can help you!