A new variant of the Ursnif banking Trojan has been detected and the actors behind the latest campaign have adopted a new tactic to spread the malware more rapidly.
Ransomware attacks may make the headlines, but banking Trojans can cause considerably more damage. The $60 million heist from a Taiwanese bank last month shows just how serious infection with banking Trojans can be. The Dridex Trojan raked in more than $40 million in 2015.
The Ursnif banking Trojan is one of the most commonly used Trojans. As with other banking Trojans, the purpose of the Ursnif Trojan is to steal credentials such as logins to banking websites, corporate bank details, and credit card numbers. The stolen credentials are then used for financial transactions. It is not uncommon for accounts to be emptied before the transactions are discovered, by which time the funds have cleared, have been withdrawn, and the criminal’s account has been closed. Recovering the stolen funds can be impossible.
Infection will see the malware record a wide range of sensitive data, capturing credentials as they are entered through the browser. The Ursnif banking Trojan also takes screenshots of the infected device and logs keystrokes. All of that information is silently transmitted to the attacker’s C2 server.
Banking Trojans can be installed in a number of ways. They are often loaded onto websites where they are downloaded in drive-by attacks. Traffic is generated to the malicious websites via malvertising campaigns or spam emails contacting hyperlinks. Legitimate websites are compromised using brute force tactics, and kits loaded to the sites that prey on individuals who have failed to keep their software up to date. Oftentimes, downloads are sent via spam email, hidden in attachments.
Spam email has previously been used to spread the Ursnif banking Trojan, and the latest campaign is no different in that respect. However, the latest campaign uses a new tactic to maximize the chance of infection and spread infections more rapidly and widely. Financial institutions have been the primary target of this banking Trojan, but with this latest attack method they are far more widespread.
Infection will see the user’s contact list abused and spear phishing emails sent to each of the user’s contacts. Since the spear phishing emails arrive from a trusted email account, the likelihood of the emails being opened is significantly increased. Simply opening the email will not result in infection. For that to occur, the recipient must open the email attachment. Again, since it has come from a trusted sender, that is more likely.
The actors behind this latest Ursnif banking Trojan campaign have another trick to increase trust and ensure their payload is delivered. The spear phishing emails contain message threads from past conversations. The email appears to be a response to a previous email, and include details of past conversations.
A short line of text is included as a prompt to get the recipient to open the email attachment – A Word document containing a malicious macro. That macro needs to be authorized to run – if macros have not been set to run automatically, but it will not until the Word document is closed. When the macro runs, it launches PowerShell commands that download the Ursnif Trojan, which then starts logging activity on the infected device and sends further spear phishing emails to the new victim’s contact list.
This is not a brand-new tactic, but it is new to Ursnif – and it is likely to see infections spread much more quickly. Further, the malware incorporates a number of additional tactics to hamper detection, allowing information to be stolen and bank accounts emptied before infection is detected – the Trojan even deletes itself once it has run.
Malware is constantly evolving, and new tactics are constantly developed to increase the likelihood of infection. The latest campaign shows just how important it is to block email threats before they reach end users’ inboxes.
With an advanced spam filter such as SpamTitan in place, malicious emails can be blocked to stop them from reaching end user’s inboxes, greatly reducing the risk of malware infections.