Cyber Security Threat Summary:
A less detectable version of the RomCom backdoor was used to target attendees of the Women Political Leaders Summit in Brussels, which centers on gender equality and women in politics. The attackers created a fake website resembling the official WPL portal to lure individuals looking to participate or learn about the summit. According to a Trend Micro report, this updated variant employs a more covert approach with a new TLS enforcement technique in its command and control communications, making it challenging to detect the culprits, known as Void Rabisu.

Moreover, this recent attack solidifies the group’s transition from haphazard ransomware attacks linked to a Cuba ransomware affiliate to a sophisticated cyberespionage effort that includes the exploitation of previously unknown vulnerabilities in Microsoft software. In August 2023, Void Rabisu established a malicious website with the address wplsummit[.]com mimicking the legitimate Women Political Leaders website hosted at wplsummit[.]org. The counterfeit website had a Videos & photos button that led to a OneDrive folder. This folder featured pictures taken from the real event site over two days and included a malware downloader labeled ‘Unpublished Pictures’. This harmful file, signed with an Eibor LLC certificate, serves as a self-extracting archive with 56 fake photos to divert attention. Simultaneously, it downloads a second encrypted file from a remote server. The second payload is a dynamic link library (DLL) that’s decrypted and loaded directly into the computer’s memory to avoid detection. It then proceeds to fetch the necessary components for establishing communication with the attacker’s server.

Researchers at Trend Micro warn that Void Rabisu is likely to target significant conferences related to special interest groups, so caution is advised when visiting event websites.

Security Officer Comments:
The cyberespionage group has also released a new version of the RomCom backdoor, which threat actors refer to as RomCom 4.0. This version also known as Peapod marks the fourth significant release of this malware by Void Rabisu. Compared to its predecessor, RomCom 3.0, this new variant has undergone substantial changes to become lighter and more discreet. It now supports only ten commands, down from the previous 42. Instead of using modified MSIs to drop components directly onto devices, RomCom 4.0 employs an exe file to fetch XOR-encrypted DLLs, loading them into memory. This version also introduces new features related to Transport Layer Security to enhance communication security with the C2 server, forcing the use of TLS version 1.2. The goal of these changes is to make C2 communication more resistant to surveillance and possibly enable attackers to select suitable victims more effectively. While the exact tactics and motives of Void Rabisu remain unclear, its evident that the development of this backdoor continues with an increasing focus on cyber espionage.

Suggested Correction(s):
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://www.bleepingcomputer.com/