Networking equipment vendor Zyxel warned its customers of a series of attacks that have been targeting some of its enterprise firewall and VPN server solutions. The threat actors are targeting the USG, ZyWALL, USG FLEX, ATP, and VPN series running on-premise ZLD firmware. The company states that devices running the Nebula cloud management mode are not impacted.
“We recently became aware of a sophisticated threat actor targeting a small subset of Zyxel security appliances that have remote management or SSL VPN enabled, namely in the USG/ZyWALL, USG FLEX, ATP, and VPN series running on-premise ZLD firmware.” reads the email sent to the customers by the company. “We’re aware of the situation and have been working our best to investigate and resolve it.”
The vendor reported that attackers are attempting to access network devices through WAN. Upon accessing the devices, attackers then bypass authentication and establish SSL VPN tunnels with unknown user accounts (i.e. ”zyxel_slIvpn”, “zyxel_ts”, or “zyxel_vpn_test”) to manipulate the device’s configuration.
The company did not reveal if the hackers are exploiting a known vulnerability or a zero-day flaw.
At the time of this writing, it is not clear if the hackers breached one of the customers of the vendor.
(SecurityAffairs – hacking, Zyxel)