Cybercriminals are continuously evolving their phishing attacks, introducing new techniques and tactics in their attempts to trick victims, bypass security measures, and avoid detection.

A new Threat Spotlight from Barracuda Networks details three novel tactics that were detected in phishing attacks during January 2023. 

Barracuda researchers analyzed data of phishing emails blocked by Barracuda systems. And while the overall volume of attacks using these tactics is currently low – with each tactic making up less than 1% of attempted phishing attacks – they are widespread, with between 11% and 15% of organizations affected, often with multiple attacks. 

The three attack tactics detailed by Barracuda are:

• Attacks using Google Translate web links.

In January, our researchers noted email attacks that used the Google Translate service for websites to hide malicious URLs (web page addresses). 

The tactic works like this: The attackers use poorly-formed HTML pages or a non-supported language to prevent Google from translating the webpage – and Google responds by providing a link back to the original URL stating that it cannot translate the underlying website.

The attackers embed that URL link in an email and if a recipient clicks on it, they are taken to a fake but authentic-looking website that is in fact a phishing website controlled by the attackers.

These attacks are difficult to detect since they contain a URL that points to a legitimate website. As a result, many email filtering technologies will allow these attacks through to users’ inboxes.

Further, the attackers can change the malicious payload at the time of email delivery, making them even harder to spot.  

Our data shows that just under one-in-eight (13%) of organizations were targeted with this type of phishing email in January 2023, each receiving on average around eight such emails during the month.

• Image-based phishing attacks.

Image based attacks have been commonly used by spammers and Barracuda researchers have found that attackers are now increasingly using images, without any text, in their phishing attacks. These images, which can be fake forms such as invoices, include a link or a callback phone number that, when followed up, leads to phishing. Because these attacks do not include any text, traditional email security can struggle to detect them. 

Our data shows that around one-in-10 (11%) organizations were targeted with this type of phishing email in January 2023, each receiving on average around two such emails during the month.

Barracuda researchers believe that image-based phishing will be an increasingly popular tactic for cybercriminals in the future. 

• The use of special characters in attacks

Hackers often use special characters, such as zero-width Unicode code points, punctuation, non-Latin script, or spaces, to evade detection. This type of tactic is also used in “typo-squatting” web address attacks, which mimic the genuine site but with a slight misspelling. When they are used in a phishing email, the special characters are not visible to the recipient.

The tactic can work like this: An attacker inserts a zero-width (no) space within the malicious URL embedded in a phishing email, breaking the URL pattern so that security technologies do not detect it as malicious.

Detection of such attacks can also be difficult because there are legitimate purposes for the use of special characters, such as within email signatures. 

Barracuda researchers found that in January 2023, more than one-in-seven (15%) organizations received phishing emails that use special characters in this way, each receiving on average around four such emails during the month. 

“Phishing is a common starting point for many cyberattacks, including ransomware, financial fraud and credential theft, and cybercriminals continue to develop their phishing approaches to trap unwary recipients and avoid being spotted and blocked,” said Olesia Klevchuk, product marketing director, Email Protection at Barracuda.

“To defend your organization, you need AI-enhanced email protection that can inspect the context, subject, sender, and more to determine whether a benign-looking email is in fact a well-disguised attack,”

“You also need to train your employees to understand, identify and report suspicious messages, plus tools that enable you to quickly identify and remove any traces of a malicious email from user inboxes and compromised accounts should a malicious email manage to break through.”