Linux Vulnerabilities: The Antidote to This Linux Security Poison
In August 1991, Linus Torvalds, a student at the University of Helsinki, created an operating system that could be a free, open-source alternative to MINIX. He said about starting Linux, "Hello everybody out there using minix - I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu)..."
Little did Torvalds know, his hobby would become one of the most powerful systems only thirty years later, assisting billions of devices worldwide. This system, Linux, makes up almost 3.08% of all the operating systems used worldwide. As the backbone to a multitude of servers, workstations, kiosks, and other front-line devices throughout the globe, it is imperative for organizations to keep their Linux environments secure while running at all times.
That's the ideal, but the reality isn't as simple, especially with over 1,050 cyber security vulnerabilities being detected in the Linux kernel in the last five years to date. This article will take a look at these network security threats and the best ways to approach and mitigate such issues.
What Are Some Common Types of Linux Vulnerabilities?
While Linux web application security vulnerabilities are a growing problem for admins and IT teams, it is of great importance to understand the common types of network security issues to be a step ahead in bolstering your system against them. Here are some Linux issues you should be familiar with:
Denial of Service (DoS) Vulnerabilities
As the name suggests, a Denial of Service (DoS) vulnerability is when exploits in cyber security carry out attacks that prevent the intended users from accessing their systems and services by shutting them down. Such attacks can prevent the account holders of a bank from accessing the bank's services, for example.
DoS is generally achieved by overloading target systems with excessive traffic or sending them information that can potentially result in triggers, eventually causing a crash in data and network security. Further, this form of attack is classified into specific types based on the attack vector, such as Ping of Death, Buffer Overflow, Teardrop, and SYN Flood.
Remote Code Execution (RCE) Vulnerabilities
One of the most common types of cyber security vulnerabilities by far, Remote Code Execution (RCE) can result in attacks in network security that allow malicious code on target systems from afar. These bugs can cause full-scale cloud security breaches, allowing the attackers to gain full control over the exploited systems, thereby compromising entire web servers due to web application security vulnerabilities.
Buffer Overflow Vulnerabilities
Buffer overflows are yet another common form of Linux cyber security vulnerabilities that can cause arbitrary code execution in target systems, thereby paving the way for threat actors to gain unauthorized access to the network.
This occurs when programs attempt to place data in a memory region past a buffer. Such exploits in cyber security are found in both web and application servers, as well as in custom web application code.
Buffer overflow attacks in network security can be classified into two types. In stack-based buffer overflows, malicious code is sent to applications that store the data in a stack buffer. In heap-based buffer overflows, the malicious code floods the program's memory space, causing the heap memory data to be overwritten. Some of the other common web application security vulnerabilities affecting Linux systems include Cross-Site Scripting (XSS), Cross-Site Request Forgery (CSRF), and SQL Injection.
Linux Vulnerabilities Over Time and Their Impact
If we were to consider the earliest Linux virus ever discovered, we would have to begin with Staog, discovered in 1996. Over the years, as the kernel's security matured, so too did methods of exploits in cyber security.
While Staog reportedly did not contain a critical payload to damage systems, the newer Linux cyber security vulnerabilities are much deadlier. From leakage of data and information to memory corruption in the affected systems, these network security threats can be incredibly harmful to an enterprise's security, as well as its normal operations. Here's a look at some of the most notorious Linux vulnerabilities discovered in the past.
In the second half of 2022, Zero Day Initiative, which focuses on international software vulnerabilities, identified this network security threat in the ksmbd file server module of the Linux kernel. This problem was rated to be of Critical severity, owing to its CVSSv3 score of 10.0.
Primarily related to the faulty use of dynamic memory allocation, or use-after-free vulnerability, it allowed unauthenticated, remote threat actors to execute code on systems that had ksmbd enabled.
Fortunately, this bug could not spread its talons and cause much destruction since ksmbd was disabled by default in most Linux distros. However, certain versions of Debian and Ubuntu were affected by the bug but had the fixes released in the subsequent versions.
Another one of these high-severity cyber security vulnerabilities was made public in February 2022 after it affected the Linux kernel by leveraging a heap out-of-bounds write error, particularly in nft_fwd_dup_netdev_offload in net/netfilter/nf_dup_netdev.c, a netfilter subcomponent of the kernel that enables the implementation of various networking-related operations.
Typically, out-of-bounds errors occur in software in case the program writes a code outside its allocated memory area. This vulnerability affected Red Hat Linux patching versions 8.3 and above, as well as certain Debian upgrades, eventually leading to system crashes or elevation of privileges.
Also discovered in 2022, keeping Linux IT administrators busy, Dirty Pipe is another vulnerability that focused on the escalation of local privileges in Linux kernel versions 5.8 and above. Threat actors could overwrite files with just read-only permissions, which means malicious applications could gain full control over the system.
Primarily affecting Android devices, Dirty Pipe was assigned a high severity rating to its CVSSv3 score of 7.8. The name of this network security threat derives from how this breach reads, writes, and distributes data via pipes. So, by leveraging the Dirty Pipe vulnerability, malicious actors can instigate exploits in cyber security to modify data in the system files.
The last of the Linux cyber security vulnerabilities we will discuss is Polkit, an authentication framework that controls system-wide privileges, seeking to elevate them for threat actors. This network security threat, with a CVSSv3 score of 7.8 (high severity), was detected in the pkexec application.
First detected in 2022, this vulnerability managed to stay hidden for over 12 years, even though it affected all versions of pkexec since its initial release in May 2009.
This vulnerability affected several popular Linux distros, such as Debian, Fedora, CentOS, and even Ubuntu, and threat actors were able to obtain full root privileges on the default installations of these distros.
How Can I Safeguard My Linux-Based Network from Exploits & Vulnerabilities?
As enterprises’ digital footprint grows, so do the network security threats and web application security vulnerabilities that can result in various problems. A slight slip or a little oversight, and the next thing you know, your data and network security are facing an attack from cybercriminals.
Hence, it is of paramount importance to strategize and develop proactive measures to fend off these cyber security vulnerabilities and attacks in network security. Below are some tips and best practices to follow to secure your Linux-based network and systems.
Leverage Linux Kernel Lockdown
Restricting access to the features and data structures of the Linux kernel by leveraging Linux Kernel lockdown is one of the most powerful ways to secure Linux systems. Once enabled, this prevents:
- Any unprivileged access to the Linux systems and their kernel memory.
- Unsigned kernel modules from being loaded.
- Secure boot restrictions from being overridden.
Regularly Audit Open Ports
Ports are the most essential component for all Internet-facing activities. However, they are also one of the easiest doorways for threat actors to creep in and instigate exploits in cybersecurity in the case that these ports are left open unintentionally or accidentally.
Some common causes of this mistake are when an admin opens a specific port to perform an action but forgets to close it, or when installed software changes the firewall configuration and keeps certain ports open.
Hence, it is highly important to perform port audits at regular intervals to check for open ports and close the ones that aren't supposed to be left open immediately to protect your data and network security.
Perform Regular Security Audits
Performing regular audits is one of the most foolproof ways to secure your Linux network. By using the Linux Auditing System, admins can audit the kernel and collect important logs on system activities. These logs provide admins with critical insights into the data and network security and stability of their systems.
Ensure Timely Patching of Your OS & software
When it comes to fending off cybersecurity vulnerabilities in your network, patch management for your operating system and third-party applications is always a prerequisite. The above-mentioned instances of web application security vulnerabilities in Linux stand as proof that networks are in danger, not just from third-party data and network security issues but also from the ones camping in the kernel.
With problems growing at an alarming pace over the years, manually scanning the network for vulnerable distros or third-party applications is just the final nail in the coffin. Combating this exponential growth demands automation—specifically, an automated patch management software that scans the network, detects vulnerable components, and deploys mitigations almost instantaneously.
ManageEngine Patch Manager Plus checks all the boxes when it comes to safeguarding your network from Linux cyber security vulnerabilities, be it applications or the operating system as a whole. Right from a single console, this solution lets you automate the patching process for your data and network security and deploy patches to all major Linux distros as well as Windows, macOS, and over 850 third-party applications.
What's more? Integrating a third-party vulnerability scanning solution, such as Tenable, is easy-breezy with Patch Manager Plus, enabling real-time vulnerability monitoring and mitigation across the entire network.
Don't take our word for it. Try out the fully functional, 30-day, free trial of Patch Manager Plus, and see how easy it can be to thwart Linux cyber security vulnerabilities in your network.
Final Thoughts on Protecting Against Linux Vulnerabilities
Securing your Linux systems against the plethora of cybersecurity vulnerabilities that exist is no longer a choice but a necessity. To sum up, there isn't just a single antidote to Linux network security issues.
Rather, it is a set of proactive measures that include kernel hardening, constant data and network security monitoring, audits of misconfigurations and open ports in the network, and regular patch deployments to keep systems updated.
To better secure your network via proactive security patching, you can take a look at the Linux patching best practices for automating Linux systems security deployment.