IoT Expands the Botnet Universe
In 2018, we witnessed the dramatic growth of IoT devices and a corresponding increase in the number of botnets and cyberattacks. Because IoT devices are always-on, rarely monitored and generally use off-the-shelf default passwords, they are low-hanging fruit for hackers looking for easy ways to build an army of malicious attackers. Every IoT device added to the network grows the hacker’s tool set.
Botnets comprised of vulnerable IoT devices, combined with widely available DDoS-as-a-Service tools and anonymous payment mechanisms, have pushed denial-of-service attacks to record-breaking volumes. At the same time, new domains such as cryptomining and credentials theft offer more opportunities for hacktivism.
Let’s look at some of the botnets and threats discovered and identified by Radware’s deception network in 2018.
A new botnet tried to deliver its dangerous payload to Radware’s newly deployed IoT honeypots. The honeypots registered multiple exploit attempts from distinct servers, all located in popular cloud hosting providers based in Europe. The botnet creators intended to sell 290Gbps DDoS attacks for only $20. Further investigation showed that the new bot used an atypical central scanning method through a handful of Linux virtual private servers (VPS) used to scan, exploit and load malware onto unsuspecting IoT victims. At the same time, the deception network also detected SYN scans originating from each of the exploited servers indicating that they were first performing a
mass scan before attempting to exploit the IoT devices, ensuring that ports 52869 and 37215 were open.
A new piece of malware that takes advantage of Android-based devices exposing debug capabilities to the internet. It leverages scanning code from Mirai. When a remote host exposes its Android Debug Bridge (ADB) control port, any Android emulator on the internet has full install, start, reboot and root shell access without authentication.
Part of the malware includes Monero cryptocurrency miners (xmrig binaries), which are executing on the infected devices. Radware’s automated trend analysis algorithms detected a significant increase in activity against port 5555, both in the number of hits and in the number of distinct IPs. Port 5555 is one of the known ports used by TR069/064 exploits, such as those witnessed during the Mirai-based attack targeting Deutsche Telekom routers in November 2016. In this case, the payload delivered to the port was not SOAP/HTTP, but rather the ADB remote debugging protocol.
Less than a week after ADB Miner, a third new botnet variant triggered a trend alert due to a significant increase in malicious activity over port 8080. Radware detected a jump in the infecting IPs from around 200 unique IPs per day to over 2,000 malicious unique IPs per day. Further investigation by the research team uncovered a new variant of the Satori botnet capable of aggressive scanning and exploitation of CVE-2017-18046 — Dasan Unauthenticated Remote Code Execution.
The rapidly growing botnet referred to as “Satori.Dasan” utilizes a highly effective wormlike scanning mechanism, where every infected host looks for more hosts to infect by performing aggressive scanning of random IP addresses and exclusively targeting port 8080. Once a suitable target is located, the infected bot notifies a C2 server, which immediately attempts to infect the new victim.
Memcached DDoS Attacks
A few weeks later, Radware’s system provided an alert on yet another new trend — an increase in activity on UDP port 11211. This trend notification correlated with several organizations publicly disclosing a trend in UDP-amplified DDoS attacks utilizing Memcached servers configured to accommodate UDP (in addition to the default TCP) without limitation. After the attack, CVE2018-1000115 was published to patch this vulnerability.
Memcached services are by design an internal service that allows unauthenticated access requiring no verification of source or identity. A Memcached amplified DDoS attack makes use of legitimate third-party Memcached servers to send attack traffic to a targeted victim by spoofing the request packet’s source IP with that of the victim’s IP. Memcached provided record-breaking amplification ratios of up to 52,000x.
Hajime Expands to MikroTik RouterOS
Radware’s alert algorithms detected a huge spike in activity for TCP port 8291. After near-zero activity on that port for months, the deception network registered over 10,000 unique IPs hitting port 8291 in a single day. Port 8291 is related to a then-new botnet that exploits vulnerabilities in the MikroTik RouterOS operating system, allowing attackers to remotely execute code on the device.
The spreading mechanism was going beyond port 8291, which is used almost exclusively by MikroTik, and rapidly infecting other devices such as AirOS/Ubiquiti via ports: 80, 81, 82, 8080, 8081, 8082, 8089, 8181, 8880, utilizing known exploits and password-cracking attempts to speed up the propagation.
Satori IoT Botnet Worm Variant
Another interesting trend alert occurred on Saturday, June 15. Radware’s automated algorithms alerted to an upsurge of malicious activity scanning and infection of a variety of IoT devices by taking advantage of recently discovered exploits. The previously unseen payload was delivered by the infamous Satori botnet. The exponential increase in the number of attack sources spread all over the world, exceeding 2,500 attackers in a 24-hour period.
Radware’s automation algorithm monitored the rise of Hakai, which was first recorded in July. Hakai is a new botnet recently discovered by NewSky Security after lying dormant for a while. It started to infect D-Link, Huawei and Realtek routers. In addition to exploiting known vulnerabilities to infect the routers, it used a Telnet scanner to enslave Telnet-enabled devices with default credentials.
A new stray QBot variant going by the name of DemonBot joined the worldwide hunt for yellow elephant — Hadoop cluster — with the intention of conscripting them into an active DDoS botnet. Hadoop clusters are typically very capable, stable platforms that can individually account for much larger volumes of DDoS traffic compared to IoT devices. DemonBot extends the traditional abuse of IoT platforms for DDoS by adding very capable big data cloud servers. The DDoS attack vectors supported by DemonBot are STD, UDP and TCP floods.
Using a Hadoop YARN (Yet-Another-Resource-Negotiator) unauthenticated remote command execution, DemonBot spreads only via central servers and does not expose the wormlike behavior exhibited by Mirai-based bots. By the end of October, Radware tracked over 70 active exploit servers that are spreading malware
and exploiting YARN servers at an aggregated rate of over one million exploits per day.
YARN allows multiple data processing engines to handle data stored in a single Hadoop platform. DemonBot took advantage of YARN’s REST API publicly exposed by over 1,000 cloud servers worldwide. DemonBot effectively harnesses the Hadoop clusters in order to generate a DDoS botnet powered by cloud infrastructure.
Always on the Hunt
In 2018, Radware’s deception network launched its first automated trend-detection steps and proved its ability to identify emerging threats early on and to distribute valuable data to the Radware mitigation devices, enabling them to effectively mitigate infections, scanners and attackers. One of the most difficult aspects in automated anomaly detection is to filter out the massive noise and identify the trends that indicate real issues.
In 2019, the deception network will continue to evolve and learn and expand its horizons, taking the next steps in real-time automated detection and mitigation.