What Is Arbitrary Code Execution (ACE)?

Arbitrary code execution (ACE) refers to an attacker’s ability to run code of their choice on a target machine or process. It allows the attacker to gain unauthorized access or perform actions beyond the intent of the application's creators, potentially leading to data theft, corruption, or system compromise. 

ACE is a critical security concern because it allows an attacker to execute commands that affect the host system without restriction. Attackers can leverage this execution privilege to install malware, create backdoors, or gain persistent access to sensitive environments. There are several common vulnerabilities that lead to ACE, including deserialization, the LDD command (list dynamic dependencies) in Linux systems, memory safety issues, and type confusion.

In this article:

How Does Arbitrary Code Execution Work? 

Arbitrary code execution works by exploiting vulnerabilities in software or its environment. Commonly, attackers take advantage of flaws in input validation, buffer overflows, or misconfigurations. By carefully crafting input or data that the targeted software does not correctly handle, an attacker can force the application to execute unintended code paths or commands, taking control of the process or system.

For instance, if a vulnerability allows an attacker to manipulate the memory of a running process, they might overwrite function pointers or return addresses. This manipulation redirects the execution flow to attacker-controlled code, achieving arbitrary code execution. Techniques such as stack overflow, heap overflow, or use-after-free are often employed in such exploits.

Remote Code Execution (RCE) and Arbitrary Code Execution (ACE): What Is the Difference? 

RCE is a subset of ACE, focusing specifically on the ability to execute code from a remote location, without direct access to the target system. This distinction underlines the attack’s origin; while ACE encompasses any unauthorized code execution, RCE emphasizes the remote aspect of the attack.

RCE threats typically involve exploiting vulnerabilities in exposed services or software that accept input from remote users. By contrast, ACE vulnerabilities can exist in any part of a system that processes untrusted data, whether locally or remotely. Security measures must account for both local and remote vectors to fully protect against unauthorized code execution.

Learn more in our detailed guide to remote code execution

Arbitrary Code Execution Vulnerabilities

Here are common vulnerabilities that can result in ACE.


Deserialization vulnerabilities occur when an application insecurely deserializes user-supplied data without adequate validation. This can lead to ACE if attackers manipulate the serialized objects to execute arbitrary code upon deserialization. Many programming languages and platforms are susceptible to deserialization flaws, especially when dealing with complex object graphs or external data sources.

Mitigating deserialization vulnerabilities requires careful handling of serialized data, including implementing strict type checks, using safe deserialization libraries, and avoiding serialization of sensitive information. Emphasizing secure coding practices and input validation can prevent attackers from leveraging deserialization to achieve arbitrary code execution.

Memory Safety

Memory safety issues are a common cause of arbitrary code execution. Vulnerabilities like buffer overflows, use-after-free, and double-free errors allow attackers to manipulate the application’s memory. These flaws can lead to the execution of malicious code by corrupting memory structures or altering the control flow of programs.

Adopting memory-safe languages or employing runtime protection mechanisms in non-memory-safe languages can reduce these risks. Techniques such as bounds checking, automatic memory management, and stack canaries help prevent memory safety vulnerabilities from being exploited for arbitrary code execution.

Type Confusion

Type confusion vulnerabilities arise when an application incorrectly processes different data types, leading to unexpected behavior. Attackers exploit these vulnerabilities by forcing the application to treat one type of data as another, potentially executing arbitrary code if they can manipulate the memory layout precisely.

Preventing type confusion requires strict type checking, code reviews, and employing modern programming languages that enforce type safety. Static analysis tools and runtime checks can also help detect and mitigate type confusion vulnerabilities before they can be exploited.

6 Examples of Recent Arbitrary Code Execution Attacks 

Here are some examples of notable attacks that involved ACE.

1. Log4j Arbitrary Code Execution Vulnerability (CVE-2021-44832) 

The Log4j vulnerability, identified as CVE-2021-44832, highlights a significant arbitrary code execution risk within the widely-used Log4j logging utility. This vulnerability stems from the way Log4j handles log message substitution. It allows attackers to manipulate log messages or log message parameters, which can then execute arbitrary code loaded from LDAP servers when logging events are processed. 

Developers and administrators are urged to review their systems for the presence of vulnerable Log4j versions and to apply necessary updates promptly. 

Learn more in the Aqua Nautilus research blog

2. Spring4Shell Remote Code Execution Vulnerability (CVE-2022-22965) 

The Spring4Shell vulnerability, designated CVE-2022-22965, is a critical arbitrary code execution flaw affecting the Spring Framework, a popular open-source application framework for the Java platform. Attackers can exploit this flaw by sending specially crafted requests to applications built using the Spring Framework, thereby executing arbitrary code on the server hosting the application.

To address the Spring4Shell vulnerability, developers need to update their Spring Framework to a patched version that mitigates this risk. 

Learn more in the Aqua Nautilus research blog

3. Google Chrome Vulnerabilities

Recent updates to Google Chrome have addressed multiple vulnerabilities that could allow for arbitrary code execution. An attacker could exploit these vulnerabilities to run arbitrary code within the context of the browser. One example is CVE-2023-585.

Google’s proactive approach in regularly updating Chrome and rewarding vulnerability disclosures through their bug bounty program exemplifies efforts to mitigate risks. Users are encouraged to update their browsers promptly to protect against these and other vulnerabilities.

4. Adobe Acrobat and Reader Zero-Day (CVE-2023-26369)

In early 2023, a zero-day vulnerability (CVE-2023-26369) was discovered in Adobe Acrobat and Reader, allowing arbitrary code execution. This vulnerability was exploited through crafted PDF documents that, when opened, would execute malicious code on the victim’s system. Adobe quickly responded by issuing patches and recommending that users update their software.

This incident underscores the importance of securely handling document formats and the need for robust mechanisms to detect and prevent exploitation. Regularly updating software and exercising caution with unsolicited documents are crucial mitigation strategies.

5. Microsoft Zero-Day Exploits in Edge and Teams (CVE-2023-4863 and CVE-2023-5217)

Microsoft addressed two zero-day vulnerabilities in early 2023, affecting the Microsoft Edge browser and Microsoft Teams video conferencing service. These vulnerabilities, identified as CVE-2023-4863 and CVE-2023-5217, could lead to arbitrary code execution through specially crafted messages or web content. 

By exploiting these flaws, attackers could gain the same user rights as the current user, leading to data theft, malware installation, or further system compromise. Microsoft has since updated both software solutions to close these security gaps.

6. Apple Zero-Day Vulnerabilities (CVE-2023-42824 and CVE-2023-5217)

Apple patched several zero-day vulnerabilities, including CVE-2023-42824 and CVE-2023-5217, affecting iOS, macOS, and Safari. These vulnerabilities could be exploited to achieve arbitrary code execution by processing maliciously crafted web content. Attackers exploiting these vulnerabilities could take over affected devices.

Steps You Can Take to Mitigate Arbitrary Code Execution Vulnerabilities 

There are several measures that can help reduce the risk of an ACE attack.

1. Input Validation and Sanitization

By strictly validating and sanitizing all incoming data, applications can eliminate malicious inputs that might lead to exploitation. This process involves verifying data against expected formats, types, and ranges, and applying appropriate encoding or filtering to neutralize potential threats. Robust input validation frameworks can significantly reduce the risk of arbitrary code execution. 

2. Code Auditing and Review

Regular code audits and reviews are essential for identifying and mitigating arbitrary code execution vulnerabilities. By thoroughly examining source code for potential security issues, developers can spot dangerous code patterns, insecure API usage, or logic flaws that could be exploited. Peer reviews, automated static analysis tools, and professional security audits are effective methods for uncovering vulnerabilities.

3. Use Security Libraries and Frameworks

Security libraries and frameworks provide tested and secure functions for common tasks. These libraries offer functionalities such as input validation, output encoding, cryptographic operations, and secure communication. Choosing reputable and actively maintained libraries can substantially reduce the risk of introducing vulnerabilities through custom code.

4. Update and Patch Management

Regularly applying updates and patches to both in-house applications and third-party components alleviates known security issues. This practice extends to operating systems, libraries, frameworks, and tools used in the development and deployment environments. Implementing a structured process for tracking, testing, and deploying updates can minimize the window of opportunity for attackers to exploit vulnerabilities.

5. Use Security Solutions Offering Runtime Protection

Implementing security solutions that offer runtime protection can significantly bolster an application’s defenses against arbitrary code execution attacks. These solutions monitor application behavior in real time, detecting and preventing unusual or malicious activities that could indicate an exploit attempt. 

By integrating with the application, they can identify and block attempts to exploit known and unknown vulnerabilities, ensuring that only safe operations are executed. This can help prevent some types of arbitrary code execution.

The Cloud Native Experts
"The Cloud Native Experts" at Aqua Security specialize in cloud technology and cybersecurity. They focus on advancing cloud-native applications, offering insights into containers, Kubernetes, and cloud infrastructure. Their work revolves around enhancing security in cloud environments and developing solutions to new challenges.