What Is Remote Code Execution (RCE)?

What Is Remote Code Execution (RCE)

Remote Code Execution (RCE) attacks enable hackers to gain access and execute code on systems and devices connected to a common network, regardless of their location. An RCE attack allows attackers to take control of servers or applications, install backdoors and crypto mining or ransomware software or even take over apps or servers altogether.

Preventing Remote Code Execution attacks requires performing regular penetration tests to identify and patch any vulnerabilities hackers could exploit, while also sanitizing input and managing memory safely.

What Is Remote Code Execution RCE?

RCE falls within a larger group of vulnerabilities known as arbitrary code execution (ACE), where hackers can remotely exploit these types of vulnerabilities without needing physical access to exploit them.

These cyberattacks can have disastrous repercussions, from data loss and service disruption to lateral movement and ransomware attacks. Unfortunately, it can be challenging to detect or prevent these types of cyberattacks due to attackers employing similar techniques for multiple targets.

As an organization, you can take several measures to safeguard yourself against cyber attacks. Memory management and protection tools may help reduce buffer overflow vulnerabilities while air-gaping and immutability strategies provide additional layers of defense, along with backup and disaster recovery plans to keep your business secure from unexpected data losses.

These preventive tactics may help stop hackers from gaining RCE access to your systems and applications, but such attacks remain prevalent – Check Point research indicates there are multiple avenues through which attackers can gain RCE and execute arbitrary code.

How Does It Work?

RCE vulnerabilities allow hackers to gain full control over compromised systems, giving them full access to use malware, launch denial-of-service attacks or gain access to sensitive data.

To exploit an RCE vulnerability, attackers need to identify a flaw in either a web application or operating system – either existing vulnerabilities that have not yet been patched, or discovering and exploiting new, zero-day flaws.

Once an attack has been successful, hackers can run any arbitrary code in a vulnerable host, including code that will deface websites, steal customer data or shut down services entirely.

Make your web applications secure by validating inputs. RCE attacks often rely on language interpreter vulnerabilities like injection and deserialization, as well as memory management issues like buffer overflow. Regular vulnerability scans for all your apps to identify and fix these flaws is also essential; StoneFly offers advanced backup and disaster recovery solutions with air-gapped features to protect against RCE threats; book a demo now to see how our solution could protect against RCE.

1. Injection Attacks

Injection attacks are among the most frequently utilized tactics used by attackers to exploit web vulnerabilities. An injection attack typically involves injecting user-controlled data into an application and running code from either its database or filesystem to execute arbitrary code that can then be extracted through further manipulations of said application.

An attacker could exploit a vulnerability in Apache Log4j’s logging library to gain a command shell and take control of their system, using what’s known as a buffer overflow attack, through string copying functions that fail to check for errors before overwriting them with malicious code.

RCE attacks can occur through various software vulnerabilities or plugins; as a result, this type of RCE often forms the backbone of many cyberattacks, including ransomware such as Log4Shell and WannaCry or crypto mining malware such as EternalBlue. Furthermore, RCE was listed among CWE/SANS Top 25 Most Dangerous Programming Errors list in 2021 by cybersecurity & infrastructure security agency as being present in nine of 15 of most often exploited vulnerabilities rated.

2. Deserialization Attacks

An RCE vulnerability allows attackers to gain entry to servers and install various forms of malware – from ransomware and cryptojacking programs that steal processing power or mine cryptocurrency for them, to denial-of-service attacks and the exposure of sensitive data on those same servers.

An attack sequence typically begins with a threat actor identifying vulnerabilities which can be exploited to execute code, whether this be known vulnerabilities that have not yet been patched, or undiscovered flaws known as zero-day vulnerabilities.

Attackers employ carefully crafted input that takes advantage of vulnerabilities on a system in order to execute arbitrary code, such as file management vulnerabilities, server side template injection vulnerabilities or insecure deserialization flaws to launch their attack against it. Common vulnerabilities include file management vulnerabilities, server side template injection vulnerabilities and insecure deserialization flaws (which involves packing sets of information into string form before being deconstructed and used by applications), serialized serial data which contains hidden code can then be accepted by target applications that will execute it; out-bounds write attacks involve memory allocation issues where attackers write data outside a buffer where it will misinterpreted as code by target applications, either accepting it or outbound write attacks can enable attackers to write data outside a buffer which will lead them straight into target applications where it will executes it; Out-bounds write attacks also exist whereby attackers write data outside a buffer, where it will misinterpreted as code by applications).

3. Out-of-Bounds Write

Out-of-bounds write vulnerabilities enable attackers to alter data by writing beyond a buffer’s boundaries and into adjacent partitions, potentially leading to memory corruption, unpredictable program behavior and crashes as well as overwriting critical program data structures such as heap control blocks allowing denial-of-service attacks.

Programmers can take steps to protect memory by employing memory-safe languages such as Valgrind to identify potential memory-based security threats and safeguard their programs against exploits.

Out-of-bounds write vulnerabilities can arise when an application allocates a memory storage buffer that is too small to accommodate all user data or incorrectly calculates memory area sizes or writes data to inappropriate places. Although manually reviewing code may make these mistakes hard to spot, tools like fuzzing and memory safe programming languages are useful in quickly finding them and taking corrective actions quickly will minimize an attacker’s chances of exploiting an RCE vulnerability.

Arbitrary Code Execution and RCE

Arbitrary code execution (RCE) refers to any attempt by an attacker to remotely or locally execute code on a compromised system, whether remotely or locally executed attacks are used as attack vectors. RCE attacks can be difficult to detect but represent a very serious vulnerability.

Malicious actors take advantage of these weaknesses to gain unauthorised access and control systems, using these weaknesses for various attacks such as penetration, privilege escalation, and data exfiltration.

Buffer overflow attacks are one of the most frequently used RCE vulnerabilities. This occurs when a program writes more data than it can handle into its buffer, a temporary storage area. When that extra data overflows into adjacent memory spaces containing other data or executable code, an expertly designed attack could potentially overwrite these areas with malicious code.

Deserialization attacks are another common type of RCE vulnerability. Programmers serialize data so it is easier for it to move across networks and platforms, but an attacker could force the program into sending back invalid or unexpected data by manipulating its output stream.

How an RCE Attack Works?

Attackers use RCE vulnerabilities for various goals, from accessing sensitive data to denial-of-service attacks. Common exploits for RCE vulnerabilities include ransomware (WannaCry, ETERNALBLUE) and fileless malware (FileCop).

RCE vulnerabilities often stem from insecure web applications and can be exploited through various means. SQL injection and cross-site scripting vulnerabilities can lead to RCE attacks; deserialization attacks allow attackers to insert malicious code into serialized data, potentially leading to RCE vulnerabilities.

Attackers may gain RCE by exploiting memory vulnerabilities such as buffer overflows. Such vulnerabilities allow an attacker to write over memory meant for user input; for instance, in the infamous Log4j hack an attacker inserted malicious code into log messages that the application misinterpreted as instructions from its logs.

Once a threat actor gains access through an RCE, they can execute the payload they stored in memory to achieve their objectives – often anything from collecting monetizable information to penetrating an internal network. Implementing best practices into your cybersecurity posture can greatly increase its resilience against RCE attacks.

Impacts of Remote Code Execution Vulnerability

An exploited remote code execution vulnerability allows attackers to gain access and execute commands on a server and spread malware among client devices, potentially spreading further infections as they steal, damage and encrypt data.

RCE attacks often combine attempts at elevating privileges and seizing control on an administrative or root level with RCE attacks, heightening their severity while providing attackers with greater cover to conceal their activities more adeptly.

Organizations often face difficulty when it comes to detecting and mitigating RCE vulnerabilities. One effective way of protecting yourself against RCE is ensuring all inputs to your solution, both external sources as well as internal functions that manipulate serialized data, are thoroughly sanitized and validated before use.

Preventive measures like secure coding practices, input validation and bounds checking can help mitigate buffer overflows and their consequences. You should also implement network security solutions that block attempted exploitation of vulnerable applications and systems and detect unauthorised access. Furthermore, keep up-to-date on updates to operating systems, software applications and libraries and conduct vulnerability scans regularly to identify any issues that could lead to remote code execution (RCE).

Types of Damage an RCE Attack Causes

Attackers can leverage RCE vulnerabilities to employ malware and conduct other types of attacks, such as data destruction and disruption, device takeover, and even device control. RCE attacks may take various forms – code injection, cross-site scripting (XSS), file management vulnerabilities – among them code injection.

Buffer overflows are one of the primary methods by which attackers gain remote code execution (RCE) access to systems. Through exploiting buffer overflow vulnerabilities, attackers can execute any code they want into memory. Deserialization and out-of-bounds write vulnerabilities also allow attackers to gain unauthorized entry by hiding malicious code inside serialized data strings which will later be de-serialized by applications and executed upon deserialization by users.

To minimize these risks, organizations should conduct regular vulnerability scans and patch all vulnerable applications. They should also validate and sanitize input, in order to prevent attacks such as injection and deserialization. Isolating critical data through air-gapping and ensuring information becomes immutable once written can further mitigate risk. Finally, setting up an incident reporting procedure and encouraging employees to report suspicious activity quickly allows companies to respond more swiftly when attacks take place.

How to Identify Code Execution Vulnerabilities?

Vulnerability scanning and penetration testing are invaluable tools that can identify RCE-enabling vulnerabilities, with vulnerability scanning often being automated while penetration testing requires professional expertise from qualified personnel. Implementing access controls within your network as well as firewalls are other essential tools for protecting RCE from attack.

Once attackers gain entry to a system via RCE attacks, they can do almost anything they please – from stealing data and diverting funds, performing detailed surveillance or disrupting service to installing backdoors that allow them to regain access without exploiting vulnerabilities again.

To carry out RCE, an attacker must first identify vulnerable modules. Depending on the nature of each vulnerability, this may involve exploiting security flaws that give them control of an instruction pointer or buffer overflow vulnerabilities which allow attackers to exploit memory allocation problems to write beyond buffer bounds and overwrite memory partitions adjacent to it. Other RCE attack scenarios include SQL injection or cross-site scripting where malicious code can be introduced into applications’ input streams.

The RCE Threat

As their name implies, RCE attacks allow attackers to remotely execute code without physical access, often combined with attempts at privilege escalation as an extra layer of attack coverage and can result in any number of damaging consequences such as information disclosure, denial of service attacks and ransomware attacks.

Penetration testing designed to detect potential Remote Code Execution vulnerabilities is crucial. Applying security patches promptly reduces the window during which such vulnerabilities can be exploited; RASP solutions and intrusion detection/prevention solutions detect known attack patterns/signature.

Validating input, using secure coding practices and regularly conducting vulnerability scanning with memory management being prioritized as the focus can help identify buffer overflow attacks and deserialization and injection vulnerabilities – among many others such as deserialization/injection vulnerabilities – before any attacks are successfully launched against an application or system using RCE vulnerabilities. Once successfully exploited by attackers, RCE vulnerabilities may allow access for backdoor installation or ransomware/cryptojacking attacks such as cryptojacking where compromised servers are used to mine cryptocurrency rather than mining this type of currency mining by hackers leveraging RCE vulnerabilities against an attacker’s side, as RCE vulnerabilities allow attackers to exploit them before an attacker could install backdoor/install malware onto compromised servers used to mine cryptocurrency through exploited RCE vulnerabilities that exploit RCE vulnerabilities have been successfully exploited successfully by attackers who systematically exploit RCE vulnerabilities are exploited successfully exploited successfully exploited an attacker can then take steps such as setting up backdoor installations/installing malware which can include ransomware/cryptojacking attacks; the latter option requires using compromised servers in order to mine cryptocurrency!

1. Initial Access

Initial access is an integral component of an attack cycle, providing attackers with an entry point into vulnerable machines. Attackers commonly target web applications and employ exploits in order to gain entry. With work-from-home policies becoming more prevalent than ever, cybercrime’s threat surface has dramatically expanded making it easier for digital miscreants to gain initial entry.

Once hackers gain entry, they can leverage code to achieve their desired goals, including exfiltrating data or diverting funds, performing detailed surveillance operations or employing ransomware attacks. RCE attacks often entail using malware like ransomware.

Attackers can execute malicious code through input fields or other vulnerabilities such as SQL injection and cross-site scripting (XSS). They may even take advantage of deserialization vulnerabilities – flaws which allow attackers to inject arbitrary code into serialized data – in order to gain unauthorized access, gain complete control and compromise of a website or application, open backdoors, seize control or destroy data or install ransomware malware and more.

2. Information disclosure

RCE attacks often stem from information disclosure, when attackers exploit vulnerabilities in web applications to gain access to data that allows them to take further advantage of both them and their users.

Threat actors could exploit vulnerabilities in an e-commerce website to obtain the admin username and password, then gain entry to take over its administration account – thus making possible ransomware or cryptomining attacks, among other malicious acts.

Information disclosure may also occur through buffer overflow vulnerabilities, which occur when data exceeds its allocated memory space and overwrites adjacent partitions of memory. This vulnerability type is widespread among web applications and allows attackers to execute arbitrary code.

To avoid this scenario, remove developer comments from markup and use an automated testing solution to identify these types of vulnerabilities in your software. Furthermore, ensure any error messages are generic so as to limit revealing sensitive information to attackers.

3. Denial of Service

Attackers use RCE attacks for various goals, from data theft, malware deployment and detailed surveillance, or service outage to service disruption – the WannaCry ransomware outbreak in 2017 is an example. Threat actors search the web for known vulnerabilities before selecting one likely exploitable one and using code injection to gain entry to systems and meet their goals.

Injection attacks such as Structured Query Language (SQL), Dependency Injection and Serialization Injection can result in remote code execution (RCE), particularly when the application utilizes functions like eval to process unsanitized user input. Buffer overflow vulnerabilities also allow attackers to write data outside the allocated buffer partition and onto adjacent ones, which could allow RCE.

Attackers can use RCE vulnerabilities to compromise servers and other systems within your network, depending on which exploit is employed. Luckily, there are ways to reduce RCE vulnerabilities: Segmenting networks and installing internal firewalls can limit how far an attacker can travel once they gain a foothold on your system; applying the principle of least privilege makes it harder for attackers to move laterally through applications and escalate privilege levels more quickly.

4. Cryptomining

RCE vulnerabilities enable attackers to remotely deploy and execute code, giving them access to sensitive data, systems compromise, or severe damage – making this attack one of the most devastating cyberthreats ever witnessed.

RCE attacks typically exploit vulnerabilities in web applications, operating systems and third-party plugins to gain unauthorized access. Attackers then use their newly acquired malicious code for furthering their goals: for example spreading malware, ransomware or cryptomining.

Identification and patching of RCE vulnerabilities is crucial to combatting RCE attacks. Developers can avoid activating this exploit by validating and sanitizing user input, using secure storage practices, running vulnerability scans on each application, as well as limiting use of language functions that require evaluating unsanitized user data such as PHP’s eval function or JavaScript’s JavaScript’s javac function which do this automatically.

organizations should also monitor their network traffic for signs of an attack, such as out-of-bounds write vulnerabilities, memory management issues and buffer overflows. Spotting these and other vulnerabilities quickly can significantly shorten the window during which an attacker could exploit them.

5. Ransomware

If a RCE attack is successful, malicious code could be introduced into an application or system and used for any number of activities such as exfiltrating data, stealing sensitive financial data, diverting funds or disrupting services.

Hackers typically exploit RCE vulnerabilities by injecting vulnerable payloads through search queries, email attachments or language interpreter vulnerabilities on websites. Once executed, hackers gain full access to functions within an application or server and may exploit further weaknesses within its framework.

Threat actors could then use this access to achieve their objectives, which could include accessing compromised data, denial of service attacks, cryptojacking or installing ransomware onto servers. Such vulnerabilities are of critical concern for cybercriminals and nation-state actors; discover how StoneFly’s backup and disaster recovery solutions, equipped with airgaping and immutability features to combat attacks against critical data are the perfect defenses against such exploits and keep critical files secure – schedule a demo today to find out more!

How to Prevent Remote Code Execution Attacks?

An attacker exploiting a remote code execution vulnerability can gain entry to your system, server, or application and compromise its integrity – potentially leading to data breaches and the exposure of sensitive customer or industry information.

Once an attacker gains access, they use malicious code to create havoc (by stealing information, altering permissions, encrypting or destroying files and downloading further malware) by means of bash scripts and terminal commands fed directly into vulnerable applications or kernels.

1. Input Sanitization

Sanitizing input data is essential in protecting against remote code execution attacks that leverage untrusted user input. Sanitization entails eliminating harmful or malicious codes found within user input that could trigger unexpected actions on the server.

Unsanitized strings could lead to SQL injection attacks that allow hackers to execute commands in the database, or cross-site scripting attacks which allow them to inject malicious HTML onto websites.

To combat these attacks, blacklists can help protect against malicious input. Unfortunately, this approach can easily be bypassed by cybercriminals; for maximum protection it would be more prudent to sanitize input with whitelists and escape characters as needed – this approach helps stop code injection, deserialization and XSS attacks from happening.

2. Secure Memory Management

Secure memory management is an essential strategy in protecting against RCE attacks, particularly buffer overflow protection that stops programs from accessing RAM they shouldn’t. Tagging, bounds checking and other techniques should all be employed as safeguards.

Implement input validation and sanitization as a preventative measure against RCE attacks via deserialization vulnerabilities, where attackers manipulate serialized data so it will decompress as executable dynamic code when deserialized. This type of attack involves manipulating serialized information to decompress into executable code when deserialized, which then allows attackers to exploit vulnerabilities when deserializing it again.

Finally, network inspection should also be implemented to detect and block RCE exploits when they arise. This is especially important because hackers often employ stealthy attacks at runtime that escape detection by traditional security tools.

3. Traffic Inspection

To protect against RCE attacks, traffic inspection technologies can help. Software in your servers should also implement bound checking measures so as to prevent buffer overflows from replacing vital information stored in neighboring buffers with random code.

Other techniques for RCE attack prevention include anti-debugging, logging and monitoring your networks for any suspicious activities. A sandbox may also help detect and isolate malware.

Traffic inspection enables dynamic routing of traffic dynamically around or through security devices based on policies. Decrypted SSL connections allow for inspection and then re-encrypted before forwarding them onward. This feature is included with firewall policies, IPS policies, Layer 2 Firewall policies, virtual engines and can even blacklist traffic manually or automatically.

4. Access Control

Access control can help prevent remote code execution attacks by limiting an attacker’s capabilities based on their granted permissions. This helps limit damage from an RCE attack, which allows hackers to gain entry and steal customer data or hijack servers for cryptocurrency mining rigs, among other exploits.

Technical access control refers to policies that outline which users are eligible for privileged access, password requirements for administrator and privileged accounts, log monitoring capabilities and updates compliance as well as temporary privilege grants that adhere to the principle of least privilege.

Different vulnerabilities can lead to remote code execution attacks, including out-of-bounds writing (where an application writes outside its memory storage buffer), injection attacks such as SQL injection, and deserialization (when user-controlled data is sent directly to functions for evaluation or running commands). All these vulnerabilities can be avoided through proper implementation.


At minimum, successful RCE attacks can lead to data breaches across an organization’s various levels – from megacorps and hospitals (as was seen with last year’s WannaCry ransomware) all the way down to individuals – but can also be used for purposes such as cryptojacking, malware deployment or nation-level espionage.

Attackers begin by identifying vulnerabilities within a system or application. After doing so, they develop exploits to trigger these flaws and execute code remotely – this may involve command injection attacks, file inclusion vulnerabilities or deserialization attacks that allow hackers to exploit memory at runtime in order to bypass security tools that don’t provide visibility into memory at runtime.

Sam is an experienced information security specialist who works with enterprises to mature and improve their enterprise security programs. Previously, he worked as a security news reporter.