RCE Meaning, How It Works, Examples and Prevention

Published on: July 19, 2024

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8 min read

Remote Code Execution (RCE) is a serious cybersecurity vulnerability that allows attackers to remotely execute malicious code on a target machine. In an RCE attack, you do not need to provide any user input. A remote code execution vulnerability allows hackers to exploit a user's sensitive data without requiring physical access to your network.

RCE vulnerabilities, a form of arbitrary code execution (ACE), frequently enable full system penetration without prior access. This makes them extremely risky, since they may lead to data theft, system control, and malware distribution.

While RCE attacks have been around for a long time, the proliferation of networked devices has significantly increased their danger. So RCE attacks aren't limited to conventional systems. Understanding RCE mechanisms, consequences, and mitigation is critical for protecting your systems in today's digital environment. Beyond the fundamentals of this sort of vulnerability, we provide instances of RCE attacks and exploitations, as well as recommended practices and steps to defend yourself.

You will find what you are looking for in these areas.

• How does RCE Attacks Work?

• Why are some Firewalls Unable to Detect RCE Attacks?

• What are Examples Of RCE Attacks?

• What Kind of Cybersecurity Threat is RCE?

• How to Mitigate RCE Attacks?

• How to prevent remote code execution

• Why do Attackers Use RCE?

• How does SASE Protect Against Remote Code Execution (RCE) Attacks?

• What is the impact of Remote Code Execution?

What is RCE?

Remote Code Execution (RCE) is a type of cyber attack in which an attacker gets control of a victim's machine remotely. This control might allow the attacker to do whatever they want with the hacked machine, such as deleting files, accessing sensitive information, or using it as a launchpad for future cyber attacks .

Remote code execution (RCE) is a sort of security flaw that enables attackers to execute arbitrary code on a distant system while connecting to it over public or private networks. These flaws can exist in an operating system, a web server, or a software application installed on a device. After exploiting these vulnerabilities, the attacker can inject malicious code into the system, which can subsequently be executed remotely.

To grasp the seriousness of such an attack, consider a basic example. Consider a web server for a prominent website that contains an RCE vulnerability. An attacker identifies and exploits the vulnerability. They can now take control of the server, perhaps defacing the website, stealing client data, or even shutting down the service, inflicting significant harm to the website owner.

Furthermore, RCE is classified as part of a larger category of vulnerabilities known as arbitrary code execution (ACE). RCE is potentially the most serious sort of ACE since it can be exploited even if an attacker has no prior access to the system or device. RCE is similar to a complete compromise of the compromised system or application and can have catastrophic implications such as data loss, service interruption, the distribution of ransomware or other malware, and the attacker's lateral movement to other critical IT systems.

How does RCE Attacks Work?

Remote Code Execution (RCE) attacks often include several steps, which can result in serious data breaches, system compromises, and other malicious actions. The main steps of an RCE attack are given below”

1. Identification of vulnerabilities: The attacker starts by detecting flaws in the target's software, such as the operating system, web server, or application. This might be a known vulnerability that has not been fixed, or a new, previously unknown vulnerability, also known as a zero-day vulnerability.

2. Crafting and delivering the exploit: After detecting a vulnerability, the attacker creates an exploit, which is code that takes advantage of the vulnerability. This code, often known as an exploit, is intended to trigger the vulnerability while allowing the attacker to inject their own code into the system. This exploit is then deployed to the target machine using a variety of methods, including malicious emails, social engineering techniques, or direct assaults on vulnerable services.

3. Executing Malicious Code: The exploit activates the vulnerability, allowing the attacker to insert and execute malicious code on the machine. This code, known as the payload, gives the attacker control of the system, allowing them to carry out acts such as data theft, system disruption, or other malicious operations. Once the exploit is complete, the attacker sends it to the target machine. This might be accomplished through a variety of methods, including sending a malicious email, utilizing social engineering, or physically attacking the machine if it is connected to the internet.

RCE attacks can target a variety of vulnerabilities, such as buffer overflows, in which an application writes more data to a buffer than it can contain, and injection vulnerabilities, in which an application executes unauthorized instructions as a result of inadequately sanitized user input. These flaws enable attackers to run arbitrary code and obtain unauthorized access to systems.

Finally, once the payload is run on the target system, the attacker obtains complete control, allowing them to do whatever they want with the compromised machine.

Why are some Firewalls Unable to Detect RCE Attacks?

Firewalls are mainly created to oversee and regulate incoming and outgoing network traffic by applying specified security rules. Nevertheless, they could have difficulties in identifying Remote Code Execution (RCE) assaults due to many factors:

• Sophistication of Attacks: Remote Code Execution (RCE) attacks often target vulnerabilities present in software programs. Adversaries have the ability to create malicious payloads that mimic genuine network traffic, posing a challenge for firewalls to differentiate between regular and harmful actions.

• Encryption: Numerous Remote Code Execution (RCE) attacks often take place using secure and encrypted communication routes, such as HTTPS. Firewalls are unable to examine the contents of this communication for harmful code since they may not be able to decode it.

• Application Layer Complexity: Firewalls often function at the network or transport layer of the OSI model, which are Layers 3 and 4, respectively. RCE attacks often target vulnerabilities at the application layer, namely at OSI Layer 7. This necessitates the use of more sophisticated inspection capabilities beyond what typical firewalls provide.

• Zero-day Vulnerabilities: Zero-day vulnerabilities refer to previously undiscovered security flaws that may be exploited by remote code execution (RCE) attacks. Firewalls depend on established threat signatures and patterns, making them potentially unable to identify novel or emerging threats, like these zero-day attacks.

• Polymorphic Code: Polymorphic code refers to the employment of tactics by attackers to alter the visual characteristics of their malicious code. This alteration makes it more challenging for signature-based detection methods used by firewalls to recognize the threat.

In order to efficiently identify and counteract Remote Code Execution (RCE) threats, it is advisable for companies to have a comprehensive security strategy that encompasses many layers. This includes the use of Intrusion Detection Systems (IDS), Intrusion Prevention Systems (IPS), frequent software upgrades, and resilient endpoint protection solutions.

What is the Impact of Remote Code Execution?

RCE attacks can have disastrous consequences for enterprises and individuals, including illegal access, data breaches, service outages, denial of service (DoS), unauthorized crypto mining, and ransomware deployment. These assaults harm financial and reputational assets and represent major dangers to data security and privacy.

The impact of RCE attacks is determined by the compromised computing device's environment as well as the attacker's aims. Often, the RCE serves as an entrance point for further attacks. This might range from a simple data breach to a full takeover. A collection of specific examples of the impact of remote code execution attacks is given below.

• Penetration: RCE vulnerabilities can be used by attackers to gain initial access to a network or environment. RCE attacks often begin with a vulnerability in a public-facing application that allows for command execution on the underlying computer. Attackers can use this to acquire an early footing on a device before installing malware or accomplishing other objectives.

• Information Disclosure: RCE attacks can be used to install data-stealing malware or to run commands that extract and exfiltrate data from a susceptible device.

• Compromise the Internal Network: If the RCE-affected device is connected to the company's internal network, the attacker can use it as an entry point to spread throughout the network.

• Privilege Escalation: in many situations, systems include internal vulnerabilities that can only be discovered by individuals with inside access. RCE enables an attacker to find and exploit vulnerabilities, thereby escalating privileges and getting access to linked computers.

• Sensitive Data Exposure: RCE may be exploited to steal data from susceptible computers by installing malware or simply running commands. This can include simple copying of unencrypted data to memory-scraping malware that searches for credentials in system memory.

• Setting up a Backdoor: After compromising the computer with an RCE, the attacker can construct a backdoor to easily reconnect to the machine without having to re-exploit the vulnerability. This is referred to as persistence. This can be handy, for example, when integrating the hacked system into a botnet.

• Denial of Service (DoS): An RCE vulnerability allows attackers to execute code on a system. This code may be used to deplete system resources and cause the system to crash, or it can be used to launch a denial of service (DoS) attack on third parties.

• Cryptomining: A frequent next step after exploiting RCE is to execute cryptomining or cryptojacking malware, which leverages an infected device's CPU capabilities to mine cryptocurrency for the attacker's financial profit.

• Ransomware: Possibly the most severe effect of RCE is that attackers can install ransomware on the compromised application or server and disseminate it throughout the network, preventing users from accessing their data until they pay a ransom.

What are Examples of RCE Attacks?

RCE vulnerabilities are among the most dangerous and impactful vulnerabilities available. RCE vulnerabilities have enabled several important cyberattacks, including the following:

• BUFFER OVERFLOW: A threat actor may overrun a memory buffer by using a basic string-copying or print function that does not validate the buffer length before execution. The attacker then overwrites the return address and directs it to a buffer containing shellcode, which is run instead of the original program. The attacker obtains a command shell that runs as root, thus taking over the machine.

• Log4j: Log4j is a prominent Java logging package that is used by several Internet services and applications. In December 2021, numerous RCE vulnerabilities in Log4j were identified, allowing attackers to use susceptible apps to execute cryptojackers and other malware on compromised servers.

• DESERIALIZATION (FORMAT STRING ATTACK): Many apps have formatting capabilities that convert user input from one format to another. A threat actor might take advantage of this behavior by inserting special characters (e.g., %x,%) into the input string to attach malicious code. Because the program does not check user input, the code runs smoothly. The threat actor has now gained access to the target network and has the ability to cause havoc.

• ETERNALBLUE: WannaCry popularized malware in 2017. The WannaCry ransomware infection propagated using a weakness in the Server Message Block Protocol (SMB). This vulnerability allows an attacker to run malicious code on affected PCs, allowing the ransomware to access and encrypt valuable files.

• SQL INJECTION: Many websites use URL query strings to dynamically obtain material from databases. On a particularly susceptible e-commerce site with an SQL database, a threat actor may create a query with the appropriate requests (e.g., SELECT, UNION) to retrieve sensitive information from the database, such as admin usernames and passwords. The attacker might use the profile image upload mechanism in the admin panel to upload a PHP script and get access to a command shell.

• RCE Threat: RCE attacks aim to achieve a range of objectives. The key distinction between RCE and other exploits is that it allows for information leakage, denial of service, and remote code execution.

• WannaCry: The WannaCry ransomware assault was first detected in 2017. It was disseminated via EternalBlue, a National Security Agency-leaked vulnerability. WannaCry spreads automatically and without user intervention. It encrypts users' data and asks for a payment to decrypt it. After infiltrating a network, the assault spreads on its own. WannaCry exploits machines that have not been properly patched. Check Point Research reported a 53% rise in firms affected by WannaCry attacks in Q1 2021.

What Kind of Cybersecurity Threat is RCE?

Remote code execution (RCE) is a security flaw that enables attackers to execute arbitrary code on a distant system by connecting to it over public or private networks. RCE is part of a larger category of vulnerabilities known as arbitrary code execution (ACE). RCE is potentially the most serious sort of ACE since it can be exploited even if an attacker does not have prior access to the system or device. RCE is similar to a complete compromise of the compromised system or application and can have catastrophic implications such as data loss, service interruption, the distribution of ransomware or other malware, and the attacker's lateral movement to other critical IT systems.

Arbitrary code execution allows an attacker to execute any code on the target system. Based on the attack vector, we may categorize arbitrary code execution into two types: remote and local.

In general, remote code execution is more serious since it may be abused across a network, which is far more harmful in today's linked world. Of course, additional considerations to consider include the sort of rights necessary, user engagement, attack complexity, and so on.

How to Mitigate RCE Attacks?

Remote code execution attacks may not be identified until harm has been caused. There are several ways of entry for these attacks, making it difficult to know what to look for when attempting to detect them. In addition, RCE attacks are always changing.

Cybersecurity experts believe that the best method to deal with RCE attacks is to prevent them. Penetration testing and other types of vulnerability testing can detect and fix weaknesses that hackers may exploit. The expense of a routine vulnerability scan exceeds the potential cost of a significant data breach.

Remote code execution attacks can leverage a variety of vulnerabilities; therefore, defending against them necessitates a multifaceted strategy. Below are some best practices for detecting and mitigating RCE attacks:

• Sanitize the inputs: Attackers frequently use deserialization and injection vulnerabilities to carry out RCE. Validating and sanitizing user-supplied input before enabling the program to utilize it can assist avoid a variety of RCE attacks. Validating user input before utilizing it in an application helps to prevent a variety of RCE attacks.

• Manage memory securely: Attackers can use memory management flaws such as buffer overflows. It is critical to do frequent vulnerability scans on all programs to find buffer overflow and memory-related vulnerabilities and resolve issues before an attacker can perform RCE.

• Inspect traffic: RCE attacks occur when attackers manipulate network traffic by exploiting code flaws to gain access to a corporate system. Organizations should adopt a network security solution that detects and prevents remote system access and control, as well as attempted exploitation of susceptible applications.

• Control access: RCE allows attackers a footing in the target network, allowing them to increase access and carry out more severe operations. Access restrictions and tactics like network segmentation, zero trust policies, and access management platforms can assist prevent lateral movement, ensuring that attackers cannot escalate their assault once they have gained initial access to the target system.

How to Prevent Remote Code Execution

The preventative techniques include safe coding practices, frequent patching and updates, rigorous vulnerability scanning and penetration testing, and the use of firewalls and intrusion detection/prevention systems. There are several techniques to do RCE, hence, guarding against them necessitates a multi-layered cybersecurity approach:

• Secure Coding Practices: Secure coding techniques serve as the initial line of defense against RCE attacks. Developers must create safe code by design, using principles such as input validation, least privilege, and defense in depth. Regular code reviews and security audits can help detect and address possible vulnerabilities before they are exploited. Furthermore, this involves verifying and cleaning input data to avoid injection attacks, as well as using least privilege principles to reduce the possible consequences of a breach.

• Regular patching and updates: Attackers often target software vulnerabilities in order to exploit RCE vulnerabilities. Software manufacturers often provide updates to address known vulnerabilities, and companies must deploy these fixes as soon as possible to reduce their risk. Delayed patching can leave systems open to assaults, as demonstrated by the Zerologon hack. Microsoft's reaction to the Log4Shell issue emphasizes the need for rapid upgrades to prevent extensive exploitation risks.

• Vulnerability assessment and penetration testing: It is vital to scan the network and systems for vulnerabilities on a regular basis, as well as perform penetration tests, to assess infrastructure security. These strategies can help businesses uncover vulnerabilities that can be exploited for RCE attacks, allowing them to take proactive steps to reduce the risk. Vulnerability scanning should be done on a continuous basis, whereas penetration testing, which is more involved and costly, can be done on a regular basis.

• Implementation of firewalls and intrusion detection/prevention systems: Firewalls and intrusion detection/prevention systems (IDS/IPS) can offer an extra layer of security against RCE assaults. RCE exploits usually connect with a remote command and control (C&C) server. These programs may scan network traffic for unusual activity, block possibly dangerous C&C traffic, and notify administrators. Using firewalls to monitor and manage incoming and outgoing network traffic based on preset security rules, as well as IDS/IPS to detect and prevent possible threats, creates a strong defense against RCE assaults.

• Cybersecurity Awareness and Training: Employee education regarding the hazards of RCE attacks, as well as training to spot phishing efforts and other malicious behaviors, may greatly lower the possibility of successful assaults. Regular security awareness training sessions and security drills help employees maintain a high level of security awareness.

Furthermore, integrating reliable backup and disaster recovery (DR) solutions is critical for ensuring quick recovery and minimal damage in the event of a security compromise.

Air-gapping and immutability technologies offer strong resistance against RCE assaults, keeping important data safe and recoverable even during successful attacks.

Why do Attackers Use RCE?

Remote code execution is risky because it allows an attacker to utilize many methods. RCE vulnerabilities may be used in a variety of ways to advance typical attacks. Malware is attacker-provided code that is intended to be run on a target machine. An RCE vulnerability simply allows an attacker to spread malware in various ways.

As a result, RCE vulnerabilities may be utilized for many of the same purposes as traditional malware. RCE can be used to spread malware on a susceptible system, launch a denial-of-service (DoS) attack, or get access to sensitive data stored on the system.

How does SASE Protect Against Remote Code Execution (RCE) Attacks?

Attackers use unprotected Windows Remote Desktop Protocol (RDP) services and unpatched RCE vulnerabilities to execute commands and install malicious programs over a network. Email servers are frequently the weak link. Many firms avoid deploying endpoint security or anti-ransomware technologies on servers for fear of jeopardizing performance. Servers are a popular target for attackers due to their large vulnerability count, network exposure, and poor patch management.

Patching on time is necessary, but it is not sufficient. A Secure Access Service Edge (SASE) solution can help prevent attackers from exploiting vulnerabilities and getting access to your network. It combines four significant characteristics into a comprehensive, cloud-based secure access service edge (SASE) solution.

• Cloud-based Intrusion Prevention System: A cloud-based intrusion prevention system (IPS) identifies and stops threats to systems and applications. Cloud IPS identifies and prevents known threats using signature and anomaly detection, including common vulnerabilities and exposures (CVEs), OWASP Top 10 common mistakes, zero-day threats, and malicious connections. It allows enterprises to outsource patching for hundreds of system, server, and application software vulnerabilities. SASE includes cloud IPS, which patches newly identified vulnerabilities in browsers, apps, and systems virtually and automatically. Cloud IPS detects legitimate threats in real-time, with great performance and few false positives.

• Zero-Day Sandboxing: SASE contains extensive sandboxing (threat emulation), which scans files for hundreds of distinct signs, such as popular evasion strategies, file-opening macros, and out-of-context services, to decide which are dangerous.

• Comprehensive Traffic Inspection: The prevention-focused SASE conducts comprehensive traffic inspection across all ports and protocols.