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Note 114
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GorillaBot: An Expanding Botnet

GorillaBot is a botnet, which means a network of compromised devices remotely controlled by
cybercriminals. It typically operates by infecting vulnerable systems, which are then used to execute
various malicious tasks without the knowledge of the device owners. Botnets are often used for
large-scale attacks, such as distributed denial of service (DDoS), in which multiple compromised
devices flood a target system with traffic, causing it to crash or become unavailable.
One of GorillaBot's key features is its ability to control a large number of infected devices, which can
include computers, servers and even Internet of Things (IoT) devices such as routers and smart
home appliances. The pervasive nature of these devices, combined with often lax security
measures, makes them attractive targets for botnet infections.
This botnet operates under a command and control (C2) structure, allowing attackers to issue
commands to all infected systems at once. This centralized management makes it easy for botnet
operators to coordinate attacks, steal sensitive data or distribute additional malware to infected
machines.
GorillaBot from a technical point of view
GorillaBot operates as a sophisticated botnet, leveraging a multi-layered architecture designed to
control and exploit a large network of compromised devices. Its core functionality revolves around
using these devices to perform malicious activities, often at the behest of a central command and
control (C2) server. GorillaBot typically communicates with its C2 server through encrypted
channels, making it difficult for cybersecurity defenses to detect and analyze its traffic patterns.
The botnet typically spreads through common infection vectors, such as exploiting vulnerabilities in
Internet services or using brute force attacks to compromise insecure systems. Once a device is
infected, GorillaBot installs itself in such a way that it goes undetected by security software, often
using techniques such as rootkits or obfuscation.
Its modular design allows it to quickly adapt to new scenarios, meaning GorillaBot can be upgraded
with new capabilities, such as launching distributed denial-of-service (DDoS) attacks, stealing
sensitive information or deploying additional malware. It often operates in conjunction with other
forms of malware, creating a layered threat that is difficult to completely eradicate.

It also uses a combination of persistence techniques to maintain its position on a compromised
system, including scheduled tasks, manipulation of system services, or fileless persistence methods
that upload its malicious payload directly into memory. This allows it to survive system reboots or
traditional cleanup methods, making it extremely difficult to remove manually without specialized
tools.
Communication between individual botnet components and the C2 server typically uses techniques
such as domain generation algorithms (DGA) to create constantly changing domains, which adds
another layer of obfuscation. This approach ensures that if a C2 server goes down, the botnet can
quickly re-establish communication with a new one, maintaining its operational integrity.
In essence, GorillaBot is a highly adaptable and resilient threat that combines advanced technical
strategies to spread, hide and persist within infected systems, all while continually evolving to evade
detection and reinforce its malicious activities.

Comparisons with other botnets
GorillaBot, like many botnets, operates as a network of compromised devices controlled by a single
entity, often for malicious purposes such as launching distributed denial-of-service (DDoS) attacks,
data theft or spreading malware. Compared to other known botnets, GorillaBot has several
distinguishing characteristics that set it apart in the cyber threat arena.
For example, the Mirai botnet, one of the most infamous to date, primarily targeted IoT devices by
exploiting weak security measures such as default credentials. It was responsible for some of the
largest DDoS attacks in history. GorillaBot, while similar in its ability to leverage large networks of
compromised devices, can use more advanced techniques, such as encrypted communication
between infected devices and their command-and-control servers, making it difficult to detect.
Emotet, another well-known botnet, initially started as a banking Trojan and later evolved into a
multi-purpose threat, capable of spreading additional malware through malicious payloads. It
became very modular, which made it versatile in its attack strategies. GorillaBot could be compared
to Emotet in terms of its adaptability, as botnets often evolve over time to incorporate new evasion
and infection tactics.
While GorillaBot may not have achieved the same level of notoriety as Mirai or Emotet (although it is
well on its way to doing so), it could possess specific characteristics or tactics that make it especially
dangerous in specialized environments. For example, some botnets target specific industries or
regions, exploiting unique vulnerabilities that are not as widely exploited by more generalized
botnets.
Overall, comparing GorillaBot to other botnets such as Mirai and Emotet highlights both common
characteristics of botnet operations-such as the use of compromised devices for large-scale attacks-
and the unique evolutions each botnet undergoes to adapt to the changing cybersecurity threat
landscape. Understanding these differences is critical to developing effective defensive strategies
against GorillaBot and similar threats.

Detection and mitigation strategies
Detecting and mitigating GorillaBot (like almost all botnets) requires a combination of proactive
monitoring, advanced threat detection tools and strong cybersecurity hygiene. GorillaBot often
infiltrates systems through vulnerabilities in IoT devices, weak passwords or unpatched software, so
early detection is crucial to limit its spread.
Detection involves monitoring network traffic for unusual patterns, such as an increase in outbound
connections to known command and control servers or irregular data flows. Deploying intrusion
detection systems (IDSs) and intrusion prevention systems (IPSs) can help identify signs of infection
by analyzing network and host activity. In addition, threat intelligence feeds that are regularly
updated with the latest information can alert administrators to potential threats.
Mitigation focuses on isolating infected systems to prevent further spread, followed by a complete
removal of the malware from the botnet. This process typically involves:

● Network segmentation: Limit the movement of malicious traffic by isolating infected devices from the rest of the network.
● Device hardening: Ensure that all devices, especially IoT devices, have strong, unique
passwords and updated firmware.

● Traffic filtering: Blocking communication with known malicious IPs or domains associated
with GorillaBot's command and control infrastructure.

● Automatic patching: periodic application of security patches to correct vulnerabilities
exploited by botnets.

● Incident response: Implementation of a clear response plan to remove malware from infected systems and prevent reinfection.

Effective detection and mitigation of GorillaBot depends on continuous vigilance, as the botnet can evolve, using more sophisticated techniques to bypass traditional security measures. Therefore, a layered defense approach, combining monitoring, patching and response, is essential for organizations to protect their networks.

Indicators of Commitment (IOC)
File Hashes:
276adc6a55f13a229a5ff482e49f3a0b63cbfc2c626da269c67506636bb1ea307f134c477f307652bb884cafe98b0bf23a3be84df2435623132efd1cd9467b1703a59780b4c5a3c990d0031c959bf7cc5b37be51ee3d41c07d02795a853b857715f6a606ab74b66e1f7e4a01b4a6b2d7

Command and control (C2):
GorillaBot has five C2 servers to which it connects, but the exact IP addresses have not beendisclosed. It uses techniques such as encryption to hide its communications, often employing UDP flooding attacks.

Persistence mechanisms:
Often a script (lol.sh) is used for propagation.

The malware creates a service file (custom.service) in /etc/systemd/system/ to run at startup,downloading malicious scripts from a remote server.

Exploited vulnerabilities:
It is known to exploit the Apache Hadoop YARN RPC vulnerability for remote code execution,allowing attackers to gain high-level privileges on compromised systems.

DDoS vectors: GorillaBot uses a wide variety of attack methods, including:
UDP Flood
ACK Bypass Flood
VSE Flood
SYN Flood
The botnet demonstrates strong anti-detection capabilities, including mechanisms to bypass
honeypots by checking the /proc file system. This allows it to effectively maintain control over IoT
devices and cloud environments.

Conclusion
GorillaBot represents a potent and evolving threat within the broader botnet landscape, capable of
causing significant damage through coordinated attacks. Its architecture is based on a sophisticated
command and control infrastructure that allows it to execute a variety of malicious activities, such as
launching DDoS attacks, collecting credentials or infiltrating IoT devices. Over the years, GorillaBot
has been involved in multiple high-profile incidents, highlighting the persistent risk that botnets pose
to both organizations and individuals.
Compared to other notorious botnets, GorillaBot stands out for its ability to exploit vulnerabilities in
unprotected IoT devices and its adaptability to evade detection. This makes it especially dangerous,
as it can quickly compromise systems with weak security configurations. Moreover, its evolution
shows how attackers continue to refine their techniques, making detection and prevention
increasingly difficult.

The best defense against GorillaBot lies in a multi-layered approach to detection and mitigation,
including the implementation of IDS/IPS systems, network segmentation, strong password policies
and regular patching. By providing indicators of compromise (IOCs), organizations can improve their
threat intelligence and better protect themselves from this and similar threats. Staying vigilant,
continually updating defenses and implementing a robust incident response plan are critical steps to
minimize the risks posed by GorillaBot.
As botnets like GorillaBot evolve, cybersecurity strategies must keep pace, ensuring that the tools
and practices used to detect and mitigate these threats are up-to-date and effective. In this rapidly
changing landscape, early detection and rapid mitigation remain the most effective ways to limit the
damage and spread of botnets.

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