Phishing campaigns do not need to be especially sophisticated to be effective, as a recently identified campaign that targets Zimbra Collaboration credentials clearly demonstrates. Zimbra Collaboration, previously known as Zimbra Collaboration Suite, is a software suite that includes an email server and web client. Zimbra Collaboration email servers are targeted by a range of different threat actors, including state-sponsored hackers and cybercriminals for espionage, conducting phishing attacks, and gaining a foothold that can be used for a more extensive compromise of an organization.

This global campaign targets users’ credentials and does not appear to be targeted on any specific sector and the threat actor behind the campaign and their motives are not known. The highest number of attacks have occurred in Poland, Ecuador, and Italy. Like many phishing campaigns, the emails warn users about a security update, security issue, or pending account deactivation, and the emails appear to have been sent from an email server administrator.

The emails include an HTML attachment, which is opened as a locally hosted page in the user’s browser. The HTML file displays a Zimbra login prompt that is tailored for each organization and includes their logo and name, and the targeted user’s username is prefilled. If the user enters their password, the credentials are transmitted to the attacker’s server via an HTTPS POST request.

The campaign was identified by security researchers at ESET, who observed waves of phishing emails being sent from companies that had previously been targeted, which suggests that some of the attacks have allowed the threat actor to compromise administrator credentials and set up new mailboxes to target other organizations.

Despite the simplicity of the campaign, it has proven to be very effective, even though the login prompt in the HTTP file differs considerably from the genuine Zimbra login prompt, and the page is opened locally, which suggests a lack of security awareness training due to the failure to identify the red flags in the emails. The emails are also likely to have a low detection rate by email security solutions, as the only malicious element is a single link to a malicious host, which is within the HTML file rather than the email body,

Phishing remains one of the most effective ways for hackers to gain initial access to networks. Combatting phishing attacks requires a combination of measures. A spam filter such as SpamTitan should be used to block the emails and prevent them from reaching their intended targets. SpamTitan incorporates signature-based and behavioral detection mechanisms for identifying malware, link scanning, and reputational checks to ensure a high catch rate and low false positive rate.

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No spam filtering solution will be able to block all malicious emails without also having an unacceptably high false positive rate, so it is important to also provide regular security awareness training to employees to teach them how to recognize and avoid malicious emails. Security awareness training should also incorporate phishing simulations to give employees practice at identifying threats. If a threat is not detected, it can be turned into a training opportunity. TitanHQ’s security awareness training platform – SafeTitan – delivers instant training in response to a failed phishing simulation, and also delivers training in response to other security mistakes, ensuring training is provided when it has the greatest impact. Training data shows that SafeTitan reduces employee susceptibility to phishing attacks by up to 80%, and combined with SpamTitan email security, ensures that businesses are well protected from phishing attacks and other cyber threats.

SpamTitan and SafeTitan, like all TitanHQ solutions are available on a free trial and product demonstrations can be arranged on request.