Summary:
Since at least early May, Banking institutions in Brazil have been observed by French cybersecurity company HarfangLab being targeted by a new campaign that deploys a custom payload variant of the Windows-based AllaKore RAT called AllaSenha. The intricate infection chain involves Python scripts and a loader developed in a language called Delphi. The final stage of the attack chain employs the main payload AllaSenha RAT, which aims to steal credentials for Brazilian bank accounts leveraging Azure cloud to perform C2 communication. Targets of the campaign include banks such as Banco do Brasil, Bradesco, Banco Safra, Caixa Econômica Federal, Itaú Unibanco, Sicoob, and Sicredi. The initial access vector, though not definitively confirmed, points towards the use of malicious LNK files in phishing messages that masquerade as a PDF. The LNK file executes a Windows command shell when launched that utilizes tactics like decoy PDFS and legitimate services to provide the appearance of legitimacy to the phishing attempt. The attacker then executes a Python script named BPyCode to deploy and rotate malicious infrastructure. In addition to stealing online banking account credentials from web browsers, AllaSenha comes with the ability to display overlay windows in order to capture two-factor authentication codes and even trick a victim into scanning a QR code to approve a fraudulent transaction initiated by the attackers.

Security Officer Comments:
There is evidence to suggest that the threat actors behind the activity previously abused legitimate services like Autodesk A360 Drive and GitHub to host the payloads. The threat actor continues to utilize social engineering to trick the victim by opening a decoy pdf when the command shell executes. Further analysis of comments and code by HarfangLab revealed the source code of AllaSenha is associated with a Portuguese-speaking individual named bert1m.

Suggested Corrections:
Associated IOCs have been published in the Appendix of HarfangLab’s blog post and on their GitHub repository. YARA rules are also available in the blog post.

General Phishing Suggested Correctionss for Organizations:

• Users should always be cautious of individuals or organizations that ask for personal information. Most companies will not ask for sensitive data from its customers. If in doubt, users should verify with the company itself to avoid any potential issues.
• Users should always take a close look at the sender’s display name when checking the legitimacy of an email. Most companies use a single domain for their URLs and emails, so a message that originates from a different domain is a red flag
• As a general rule, users should not click links or download files even if they come from seemingly “trustworthy” sources.
• Check for mismatched URLs. While an embedded URL might seem perfectly valid, hovering above it might show a different web address. In fact, users should avoid clicking links in emails unless they are certain that it is a legitimate link.
• Users should always be on the lookout for any grammatical errors and spelling mistakes. Legitimate companies will often employ proofreaders and editors who ensure that the materials they send out are error-free.
• Users should not be frightened or intimidated by messages that have an alarmist tone. They should double check with the company if they are uncertain about the status of their accounts.
• Phishing emails are designed to be sent to a large number of people, so they need to be as impersonal as possible. Users should check whether the message contains a generic subject and greeting, as this can be a sign of a phishing attempt.
• Although not every end user has access to advanced anti-phishing software, they can still use the built-in protection of their email clients to filter messages. One example is setting the email client to block all images unless approved.
• Legitimate companies will never send confirmation emails unless there are specific reasons for doing so. In fact, most companies will avoid sending unsolicited messages unless it’s for company updates, newsletters, or advertising purposes.
• Users should always take the context of an email or message into account. For example, most online accounts do away with viewable member numbers, so users should be wary if they receive emails containing a “member number” for services that generally don’t use them.
• It is important to take note of unusual information in the text of the message. Any mentions of operating systems and software that are not typically used by consumers can often be indicators of a phishing attempt.

If it seems suspicious, it probably is. Users should always err on the side of caution when it comes to sending out personally identifiable information through messages and emails.

Link(s):
https://thehackernews.com/2024/05/brazilian-banks-targeted-by-new.html

https://harfanglab.io/en/insidethelab/allasenha-allakore-variant-azure-c2-steal-banking-latin-america/