FortiGuard Labs has uncovered a sophisticated botnet called “RustoBot” which uses Rust, a powerful systems programming language. This botnet targets vulnerable network devices, including TOTOLINK routers and certain DrayTek devices, exploiting command injection vulnerabilities like CVE-2022-26210 and CVE-2022-26187. Attackers exploit these vulnerabilities to gain remote access and control over affected devices. The malware campaign spreads across a wide range of architectures, including arm5, arm6, arm7, mips, and x86, targeting devices primarily in Japan, Taiwan, Vietnam, and Mexico.
RustoBot’s propagation begins with downloader scripts that deliver the initial payload to compromised web servers.
Once the payload is executed, the malware downloads a Rust-based binary tailored to the victim’s architecture. The malware then establishes control over the device and uses various obfuscation tactics to evade detection. These tactics include XOR-based encryption for configuration data and dynamic resolution of system APIs, making it harder for defenders to analyze the malware.
The botnet’s communication with command-and-control (C2) servers is conducted using DNS-over-HTTPS (DoH), blending malicious traffic with legitimate encrypted web traffic. This makes it difficult to identify the botnet’s activity within the network. RustoBot’s C2 server issues attack commands, including methods for DDoS attacks (UDP, TCP, or raw IP flooding).
These attacks are highly targeted, specifying IP addresses, ports, and packet sizes, which allows attackers to launch precise and impactful DDoS campaigns.
To mitigate the risk of RustoBot infections, organizations should update firmware on affected devices, enforce strong authentication, and monitor device activity for any signs of unauthorized access. FortiGuard recommends filtering network traffic to block communications with known C2 domains and IPs. Given the evolving nature of botnet attacks targeting IoT and edge devices, proactive mitigation, including threat intelligence and multi-layered defenses, is essential for organizations to safeguard their networks from these sophisticated threats.
