Earlier this year, Akira was observed exploiting SonicWall SSL VPN devices to breach corporate networks. Initially, researchers suspected a zero-day vulnerability was involved. However, SonicWall later attributed the incidents to an improper access control flaw identified as CVE-2024-40766, disclosed in September 2024. The flaw had been patched in August 2024, but attackers continued to exploit stolen credentials from compromised devices even after updates were applied. SonicWall advised administrators to reset all VPN credentials and update to the latest SonicOS firmware.
The latest Arctic Wolf findings reveal a persistent campaign in which multiple OTP challenges were triggered before successful logins, implying that attackers may be generating valid OTP tokens using previously harvested OTP seeds. The company confirmed that these logins were linked to devices affected by CVE-2024-40766, suggesting that stolen credentials remain a key entry point.
In a related investigation, Google’s Threat Intelligence Group (GTIG) observed a similar campaign in July, where a financially motivated group known as UNC6148 deployed the OVERSTEP rootkit on SonicWall SMA 100 series appliances. GTIG assessed that the attackers were using stolen one-time password seeds from earlier zero-day intrusions, allowing continued access even after organizations patched their systems.
Once Akira gained access to networks, the attackers moved rapidly, often initiating internal scans within minutes. According to Arctic Wolf, they used Impacket SMB session requests, Remote Desktop Protocol (RDP) logins, and Active Directory enumeration tools like dsquery, SharpShares, and BloodHound to expand their reach. A major focus was on Veeam Backup & Replication servers, where a custom PowerShell script extracted and decrypted stored MSSQL and PostgreSQL credentials.
To disable endpoint protection, Akira affiliates executed a Bring-Your-Own-Vulnerable-Driver (BYOVD) attack, using Microsoft’s legitimate consent.exe executable to sideload malicious DLLs that deployed vulnerable drivers such as rwdrv.sys and churchill_driver.sys. These drivers were then used to terminate security processes, enabling the ransomware to encrypt systems undetected.
The report notes that some compromised systems were running SonicOS 7.3.0, the very version recommended by SonicWall to mitigate such attacks. Security experts urge all administrators to reset VPN credentials and review access logs on any devices that previously used vulnerable firmware, as threat actors may still exploit stolen data to infiltrate networks.
