Cybersecurity Alert: Trojanized SonicWall VPN Software Discovered

As remote work continues to thrive, so does the potential for cyber threats, particularly those targeting VPN software. Recent findings reveal that hackers are distributing a compromised version of SonicWall’s SSL VPN NetExtender application. This malicious software aims to steal user credentials by pretending to be the legitimate client.

Understanding the Threat

SonicWall’s NetExtender is designed to facilitate secure remote connections, enabling users to access company applications and resources as if they were on-site. According to SonicWall researcher Sravan Ganachari, this tool allows employees to upload, download files, and connect to network drives seamlessly. However, what should be a secure connection has been manipulated by attackers to create a dangerous vulnerability.

Microsoft, in collaboration with network security firms, identified the campaign and dubbed the malicious software "SilentRoute." The trojanized version masquerades as NetExtender version 10.3.2.27. It was being disseminated through a fraudulent website that has since been taken down but highlights the ongoing risk of downloading software from unverified sources.

How the Attack Works

The malicious application exploits common search behaviors, luring users who are looking for NetExtender on platforms like Google or Bing. Attackers deploy tactics such as SEO poisoning, malvertising, and even social media to promote spoofed sites. Once unsuspecting users install the altered software, they unwittingly set themselves up for credential theft.

The attack modifies key components of the installer, specifically "NeService.exe" and "NetExtender.exe." These modifications allow the software to circumvent digital certificate validation, enabling it to execute malicious code seamlessly. Information about the user’s VPN configuration—including usernames and passwords—is exfiltrated to a remote server controlled by the hackers.

Ganachari explains that once users input their VPN configuration details and click “Connect,” the malicious software performs its own validation, subsequently sending sensitive data to an attacker-operated server.

The Link to ConnectWise

In a related development, G DATA, a German cybersecurity firm, has reported on a cluster of attacks nicknamed "EvilConwi." This threat involves cybercriminals abusing ConnectWise software in a method known as authenticode stuffing, where malicious code is inserted without invalidating the digital signature.

Since March 2025, G DATA has noted a surge in these attacks, primarily initiated through phishing emails or bogus websites masquerading as AI tools on platforms like Facebook. Recipients often encounter misleading links that redirect them to a Canva page, which then triggers the installation of the compromised ConnectWise software.

The Risks Behind Authenticode Stuffing

The ability to embed malicious code in seemingly legitimate software provides attackers with an effective cover for their operations. By utilizing trusted applications or elevated processes, they can operate undetected for longer periods. This particular method can also confuse users, as the software presents fake Windows update prompts to deter them from shutting down their systems, allowing attackers to maintain persistent access.

ConnectWise has since revoked the certificate used to sign these compromised binaries, but the threat remains significant. Security researcher Karsten Hahn underscores the ingenuity of these tactics, stating that attackers create remote access malware disguised as legitimate software—like an AI-based image converter from Google Chrome.

Remaining Vigilant

With cyber threats evolving constantly, it’s crucial for users to remain vigilant. Always verify the source of software downloads and keep antivirus software up to date. Training employees on recognizing potential phishing attempts and ensuring a proactive cybersecurity posture can help mitigate risks associated with these sophisticated attacks.

The ongoing developments in cybersecurity serve as a reminder of the importance of diligence in protecting personal and corporate information from nefarious actors.