15 Feb, 2023

Remote Code Execution

Vulnerability Assessment as a Service (VAaaS)

Tests systems and applications for vulnerabilities to address weaknesses.

The abbreviation of Remote Code Execution Vulnerability is RCE.

Remote Code Execution (RCE) vulnerability is a type of security vulnerability that allows an attacker to execute arbitrary code or commands on a targeted system or application remotely, usually over a network.

RCE is considered part of a broader group of vulnerabilities known as arbitrary code execution (ACE)—RCE are possibly the most severe type of ACE, because they can be exploited even if an attacker has no prior access to the system or device. This type of vulnerability can be exploited by an attacker to gain full control of the affected system or application, and potentially steal data, modify or delete files, install malware, or launch further attacks on other systems.

In the context of cybersecurity, abbreviations like RCE are commonly used to refer to specific types of vulnerabilities or attacks, which helps to facilitate communication among security professionals and researchers. Other common cybersecurity abbreviations include XSS (Cross-Site Scripting), SQLi (SQL Injection), CSRF (Cross-Site Request Forgery), and DoS (Denial of Service).

Example of vulnerable code on different programming languages

Python:

				
					import os

user_input = input("Enter a file name: ")
os.system("cat " + user_input)
				
			

This code takes input from the user, and then uses the os.system() function to execute the cat command on the user input without properly validating or sanitizing it. An attacker could supply a specially crafted file name as input to execute arbitrary commands on the system.

PHP:

				
					$user_input = $_POST['user_input'];
eval($user_input);
				
			

This code takes user input from a POST request, and then uses the eval() function to execute it as PHP code. Since eval() can execute any valid PHP code, an attacker could supply malicious code as input to execute arbitrary commands on the server.

Java:

				
					Runtime.getRuntime().exec(request.getParameter("cmd"));
				
			

This code takes a user input from a web request and passes it to the exec() method of the Runtime class without proper input validation. An attacker could supply a specially crafted input to execute arbitrary commands on the system.

C#:

				
					string cmd = Request.QueryString["cmd"];
System.Diagnostics.Process.Start("cmd.exe", cmd);
				
			

This code takes user input from a query string and then uses the Process.Start() method to execute a command on the system. An attacker could supply a specially crafted command as input to execute arbitrary commands on the system.

Examples of exploitation Remote Code Execution vulnerabilities

  1. Code injection in a web application: In this scenario, an attacker might manipulate user input on a web application to inject malicious code that can be executed on the server. For example, an attacker might inject code like <?php system($_GET[‘cmd’]); ?> into a user input field that is later processed by the server. When the server processes the input, the code is executed and the system() function is called with the user-supplied command as an argument, allowing the attacker to execute arbitrary commands on the server.

  2. XML external entity (XXE) injection: In this scenario, an attacker might manipulate XML input to an application in order to exploit an XXE vulnerability, which can be used to execute arbitrary code on the server. For example, an attacker might send a specially crafted XML file that includes an external entity that references a file containing malicious code. When the application processes the XML input, the malicious code is executed on the server, allowing the attacker to take control of the system.

  3. SQL injection: In this scenario, an attacker might manipulate user input on a web application to inject malicious SQL code that can be executed on the server. For example, an attacker might submit a specially crafted SQL query that includes a command like SELECT * FROM users; DROP TABLE users; When the server processes the query, the DROP TABLE command is executed, deleting the entire users table from the database.

  4. Insecure deserialization: In this scenario, an attacker might manipulate serialized data to exploit an insecure deserialization vulnerability in an application. For example, an attacker might send a specially crafted serialized object that exploits a vulnerability in the deserialization process, allowing the attacker to execute arbitrary code on the server.

  5. Command Injection: An attacker can inject arbitrary commands into a vulnerable system or application by manipulating user input, such as command-line arguments or environment variables. For example, an attacker could inject a command like “; rm -rf /” to delete all files on the system.

  6. Web Shells: An attacker can upload a web shell to a vulnerable system or application to gain remote access and execute arbitrary commands. Web shells are typically written in server-side scripting languages like PHP or ASP, and can provide attackers with a web-based interface to execute commands and control the system.

Privilege escalation techniques for Remote Code Execution vulnerabilities

Privilege escalation is a technique used by attackers to gain higher levels of access to a system or application, beyond what their initial level of access would allow. Remote Code Execution (RCE) vulnerabilities, privilege escalation can be especially dangerous, as it can allow an attacker to gain full control over a system or application.

Techniques used for privilege escalation of RCE vulnerabilities:

  1. Exploiting kernel vulnerabilities: In this technique, an attacker might exploit a vulnerability in the operating system kernel to gain higher levels of access to the system. For example, an attacker might exploit a buffer overflow vulnerability in a kernel module to execute arbitrary code in kernel mode, allowing them to gain full control over the system.

  2. Exploiting application vulnerabilities: In this technique, an attacker might exploit vulnerabilities in an application to gain higher levels of access to the system. For example, an attacker might exploit a vulnerability in a web application to gain administrative access to the underlying server.

  3. Privilege escalation via lateral movement: In this technique, an attacker might use the access they already have on a system or application to gain higher levels of access on other systems. For example, an attacker might use a compromised server to launch attacks on other servers on the same network, eventually gaining full control over the entire network.

  4. Credential stealing: In this technique, an attacker might steal valid user credentials from a system or application to gain higher levels of access. For example, an attacker might use a keylogger or other malware to steal the username and password of a privileged user, allowing them to log in and gain full control over the system.

  5. Exploiting setuid programs: On Unix-like systems, setuid programs are programs that run with the privileges of the program’s owner, rather than the user who launched the program. In some cases, an attacker may be able to exploit a setuid program to escalate their privileges. For example, an attacker may use an RCE vulnerability to execute code as an unprivileged user, and then use that access to escalate their privileges by exploiting a vulnerable setuid program.

  6. Exploiting service accounts: In some cases, an application may be configured to run using a service account with elevated privileges. If an attacker can exploit an RCE vulnerability in the application, they may be able to execute code using the same service account, which would give them higher levels of access.

  7. Exploiting misconfigured file permissions: On Unix-like systems, file permissions can be used to control which users have access to which files. In some cases, a misconfigured file permission could allow an attacker to escalate their privileges. For example, an attacker might exploit an RCE vulnerability to gain access to a low-privileged user’s home directory, and then discover that a file in that directory has overly permissive file permissions that allow the attacker to modify the file and execute code as a privileged user.

  8. Exploiting misconfigured services: Some services may be misconfigured, allowing an attacker to escalate their privileges. For example, an attacker might exploit an RCE vulnerability in a web application running as an unprivileged user, and then discover that the application is running with a privileged user’s environment variables set, which would allow the attacker to escalate their privileges.

  9. Exploiting race conditions: In some cases, a race condition vulnerability may exist in the system, which can be exploited to escalate privileges. For example, an attacker might exploit an RCE vulnerability to create a temporary file as an unprivileged user, and then quickly move the file to a location that is writable by a privileged user before the file is deleted. This would allow the attacker to execute code as a privileged user.

General methodology and checklist for Remote Code Execution vulnerabilities

  1. Identify the target: First, identify the target application or system you want to test for RCE vulnerabilities. Determine the software version, language, and platform used.

  2. Identify the entry points: Next, identify the entry points that could be used to trigger an RCE vulnerability. This could include inputs such as form fields, query parameters, or API endpoints.

  3. Create test cases: Create a list of test cases that cover all of the entry points identified in step 2. Each test case should include a set of input values that could potentially trigger an RCE vulnerability.

  4. Execute the test cases: Execute the test cases and observe the behavior of the application or system. Look for any unexpected or unusual behavior, such as error messages or server responses that contain system information.

  5. Analyze the results: Analyze the results of the test cases to identify any vulnerabilities that may exist. Look for any signs of code execution or system compromise, such as unexpected processes running on the server, files created or modified, or network traffic to unexpected destinations.

  6. Exploit the vulnerabilities: Once a vulnerability has been identified, attempt to exploit it in order to gain control over the system or application. Use a variety of tools and techniques to see if it is possible to execute code on the target system.

  7. Verify the vulnerabilities: Finally, verify any vulnerabilities that have been discovered by attempting to exploit them in a controlled environment. This will help to confirm that the vulnerability is indeed exploitable and to understand the extent of the damage that could be caused.

Additional tips to keep in mind when testing for RCE vulnerabilities:

Start with a targeted approach: Begin testing by focusing on the entry points that are most likely to be vulnerable, such as form fields or query parameters. This will help to prioritize testing efforts and avoid spending time on areas that are unlikely to be exploitable.

Use a variety of tools and techniques: Use a combination of automated and manual testing techniques, such as fuzzing, static analysis, and manual inspection, to identify and exploit vulnerabilities.

Test for different types of RCE vulnerabilities: Be sure to test for different types of RCE vulnerabilities, such as command injection, SQL injection, and OS command injection. Each type of vulnerability requires a slightly different approach to testing.

Test from different perspectives: Test from different perspectives, such as an unauthenticated user, an authenticated user, and a privileged user, to identify vulnerabilities that may be hidden behind different levels of access.

Keep track of testing activities: Keep detailed records of testing activities, including test cases, results, and remediation recommendations, to ensure that all vulnerabilities are properly documented and addressed.

Follow responsible disclosure practices: If you discover a vulnerability, follow responsible disclosure practices and work with the software vendor or developer to ensure that the vulnerability is properly patched and disclosed to the public in a responsible manner.

Tools set for exploiting Remote Code Execution vulnerabilities

Manual Tools:

  1. Burp Suite – Burp Suite is a popular web application testing tool that includes a range of features for testing and exploiting web vulnerabilities, including RCE. It has a proxy, scanner, spider, and other tools that allow the tester to intercept, analyze and modify web traffic.

  2. Metasploit – Metasploit is a penetration testing tool that includes a range of exploits for various vulnerabilities, including RCE. It also provides a framework for creating and testing custom exploits.

  3. PowerShell – PowerShell is a command-line shell and scripting language developed by Microsoft. It is often used by testers to run commands on target systems in order to exploit RCE vulnerabilities.

  4. Python – Python is a popular programming language that is often used for developing custom exploits and payloads for RCE vulnerabilities.

  5. Netcat – Netcat is a versatile networking tool that can be used to create a reverse shell on a target system in order to execute commands and exploit RCE vulnerabilities.

  6. Shodan – Shodan is a search engine for internet-connected devices that allows testers to identify potential targets for RCE vulnerabilities.

  7. Wireshark – Wireshark is a network protocol analyzer that can be used to identify RCE vulnerabilities by analyzing network traffic.

  8. Nmap – Nmap is a network scanning tool that can be used to identify open ports and potential vulnerabilities, including RCE.

  9. Manual Exploits – Manual exploitation techniques such as injecting malicious code through web forms, input validation bypass, and file inclusion vulnerabilities can also be used to exploit RCE vulnerabilities.

Automated Tools:

  1. Nikto – Nikto is an open-source web application scanner that can be used to identify vulnerabilities, including RCE, in web applications.

  2. Nessus – Nessus is a vulnerability scanner that can be used to identify RCE vulnerabilities in web applications and systems.

  3. OpenVAS – OpenVAS is a vulnerability scanner that can be used to identify RCE vulnerabilities in web applications and systems.

  4. Acunetix – Acunetix is a web vulnerability scanner that can be used to identify and exploit RCE vulnerabilities in web applications.

  5. ZAP – ZAP is an open-source web application scanner that can be used to identify vulnerabilities, including RCE, in web applications.

  6. SQLMap – SQLMap is an automated SQL injection tool that can be used to identify and exploit RCE vulnerabilities in web applications.

  7. Metasploit Framework – The Metasploit Framework includes a range of automated RCE exploits that can be used to test for and exploit RCE vulnerabilities in web applications and systems.

  8. Arachni – Arachni is a web application scanner that can be used to identify vulnerabilities, including RCE, in web applications.

  9. W3af – W3af is an open-source web application scanner that can be used to identify vulnerabilities, including RCE, in web applications.

  10. BeEF – BeEF (Browser Exploitation Framework) is a tool that can be used to exploit RCE vulnerabilities in web browsers.

  11. XSSer – XSSer is an open-source tool that can be used to identify and exploit RCE vulnerabilities in web applications.

Average CVSS score of Remote Code Execution vulnerabilities

Remote Code Execution (RCE) vulnerabilities, the average CVSS score can vary widely depending on the specific vulnerability and the affected software or system. However, in general, RCE vulnerabilities are considered to be some of the most severe and potentially damaging vulnerabilities.

According to a report by NIST (National Institute of Standards and Technology), the average CVSS score for RCE vulnerabilities was 9.8 out of a maximum of 10, indicating that these vulnerabilities can have a critical impact on the affected system. This is due to the fact that RCE vulnerabilities allow attackers to execute arbitrary code on the target system, which can lead to a wide range of potential consequences, from data theft and destruction to system compromise and control.

CVSS score is just one factor to consider when assessing the severity of a vulnerability, and it should be used in conjunction with other information and context specific to the system and environment in question. Ultimately, the severity of a vulnerability and the appropriate response will depend on the specific circumstances and risk tolerance of the organization or individual responsible for the affected system.

The Common Weakness Enumeration (CWE) for Remote Code Execution vulnerabilities

Here are some of the most common CWEs associated with Remote Code Execution vulnerabilities:

  1. CWE-94: Code Injection – An attacker can manipulate code execution by injecting malicious code into an application’s input.

  2. CWE-78: OS Command Injection – An attacker can execute unauthorized operating system commands by manipulating input that is passed to the system.

  3. CWE-269: Improper Privilege Management – Insufficient or improper controls can allow an attacker to execute code with elevated privileges.

  4. CWE-732: Incorrect Permission Assignment for Critical Resource – Improper permission settings can allow an attacker to execute code with elevated privileges.

  5. CWE-284: Improper Access Control – Inadequate or missing controls can allow an attacker to execute code with elevated privileges.

  6. CWE-285: Improper Authorization – Insufficient or inadequate checks can allow an attacker to execute code with elevated privileges.

  7. CWE-787: Out-of-bounds Write – An attacker can manipulate code execution by writing beyond the bounds of a buffer or other data structure.

  8. CWE-772: Missing Release of Resource after Effective Lifetime – Failing to properly release resources after use can allow an attacker to execute code with elevated privileges.

  9. CWE-611: Improper Restriction of XML External Entity Reference – Insufficient validation of XML input can allow an attacker to execute unauthorized code.

  10. CWE-798: Use of Hard-coded Credentials – Use of hard-coded credentials can allow an attacker to execute code with elevated privileges.

  11. CWE-840: Improper Enforcement of a Single, Unique Application Instance – Insufficient controls can allow multiple instances of an application to run, potentially allowing an attacker to execute code with elevated privileges.

  12. CWE-863: Incorrect Authorization – Insufficient or inadequate authorization checks can allow an attacker to execute code with elevated privileges.

  13. CWE-89: Improper Neutralization of Special Elements used in an SQL Command – Insufficient input validation can allow an attacker to execute unauthorized SQL commands.

  14. CWE-863: Incorrect Authorization – Insufficient or inadequate authorization checks can allow an attacker to execute code with elevated privileges.

  15. CWE-22: Improper Limitation of a Pathname to a Restricted Directory – Insufficient validation of input can allow an attacker to execute code outside of the intended directory.

  16. CWE-78: OS Command Injection – An attacker can execute unauthorized operating system commands by manipulating input that is passed to the system.

  17. CWE-319: Cleartext Transmission of Sensitive Information – Transmitting sensitive information in clear text can allow an attacker to execute code with elevated privileges.

  18. CWE-122: Heap-based Buffer Overflow – An attacker can manipulate code execution by overflowing heap-based data structures.

  19. CWE-434: Unrestricted Upload of File with Dangerous Type – Insufficient validation of input can allow an attacker to upload and execute unauthorized files.

  20. CWE-611: Improper Restriction of XML External Entity Reference – Insufficient validation of XML input can allow an attacker to execute unauthorized code.

A few examples of the many possible CWEs that can be associated with Remote Code Execution vulnerabilities, and the specific vulnerabilities and impacts will depend on the context and nature of the affected system.

Top 10 latests CVE related to Remote Code Execution vulnerabilities

CVE-2023-25718 – The cryptographic code signing process and controls on ConnectWise Control through 22.9.10032 (formerly known as ScreenConnect) are cryptographically flawed. An attacker can remotely generate or locally alter file contents and bypass code-signing controls. This can be used to execute code as a trusted application provider, escalate privileges, or execute arbitrary commands in the context of the user. The attacker tampers with a trusted, signed executable in transit.

CVE-2023-25717 – Ruckus Wireless Admin through 10.4 allows Remote Code Execution via an unauthenticated HTTP GET Request, as demonstrated by a /forms/doLogin?login_username=admin&password=password$(curl substring.

CVE-2023-25558 – DataHub is an open-source metadata platform. When the DataHub frontend is configured to authenticate via SSO, it will leverage the pac4j library. The processing of the `id_token` is done in an unsafe manner which is not properly accounted for by the DataHub frontend. Specifically, if any of the id_token claims value start with the {#sb64} prefix, pac4j considers the value to be a serialized Java object and will deserialize it. This issue may lead to Remote Code Execution (RCE) in the worst case. Although a `RestrictedObjectInputStream` is in place, that puts some restriction on what classes can be deserialized, it still allows a broad range of java packages and potentially exploitable with different gadget chains. Users are advised to upgrade. There are no known workarounds. This vulnerability was discovered and reported by the GitHub Security lab and is tracked as GHSL-2022-086.

CVE-2023-25136 – OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The double free can be leveraged, by an unauthenticated remote attacker in the default configuration, to jump to any location in the sshd address space. One third-party report states “remote code execution is theoretically possible.”

CVE-2023-25135 – vBulletin before 5.6.9 PL1 allows an unauthenticated remote attacker to execute arbitrary code via a crafted HTTP request that triggers deserialization. This occurs because verify_serialized checks that a value is serialized by calling unserialize and then checking for errors. The fixed versions are 5.6.7 PL1, 5.6.8 PL1, and 5.6.9 PL1.

CVE-2023-24813 – Dompdf is an HTML to PDF converter written in php. Due to the difference in the attribute parser of Dompdf and php-svg-lib, an attacker can still call arbitrary URLs with arbitrary protocols. Dompdf parses the href attribute of `image` tags and respects `xlink:href` even if `href` is specified. However, php-svg-lib, which is later used to parse the svg file, parses the href attribute. Since `href` is respected if both `xlink:href` and `href` is specified, it’s possible to bypass the protection on the Dompdf side by providing an empty `xlink:href` attribute. An attacker can exploit the vulnerability to call arbitrary URLs with arbitrary protocols if they provide an SVG file to the Dompdf. In PHP versions before 8.0.0, it leads to arbitrary unserialize, which will lead, at the very least, to arbitrary file deletion and might lead to remote code execution, depending on available classes. This vulnerability has been addressed in commit `95009ea98` which has been included in release version 2.0.3. Users are advised to upgrade. There are no known workarounds for this vulnerability.

CVE-2023-24610 – NOSH 4a5cfdb allows remote authenticated users to execute PHP arbitrary code via the “practice logo” upload feature. The client-side checks can be bypassed. This may allow attackers to steal Protected Health Information because the product is for health charting.

CVE-2023-24576 – EMC NetWorker may potentially be vulnerable to an unauthenticated remote code execution vulnerability in the Networker Client execution service (nsrexecd) when oldauth authentication method is used. An unauthenticated remote attacker could send arbitrary commands via RPC service to be executed on the host system with the privileges of the nsrexecd service, which runs with administrative privileges.

CVE-2023-24508 – Baicells Nova 227, Nova 233, and Nova 243 LTE TDD eNodeB and Nova 246 devices with firmware through RTS/RTD 3.6.6 are vulnerable to remote shell code exploitation via HTTP command injections. Commands are executed using pre-login execution and executed with root permissions. The following methods below have been tested and validated by a 3rd party analyst and has been confirmed exploitable special thanks to Rustam Amin for providing the steps to reproduce.

CVE-2023-24494 – A stored cross-site scripting (XSS) vulnerability exists in Tenable.sc due to improper validation of user-supplied input before returning it to users. An authenticated, remote attacker can exploit this by convincing a user to click a specially crafted URL, to execute arbitrary script code in a user’s browser session.

The list of CVEs is constantly being updated and full an up-to-date list of all existed Common Vulnerabilities and Exposures (CVEs) for HTTP Request Smuggling vulnerabilities can be found at official CVE website https://cve.mitre.org/

Remote Code Execution vulnerabilities exploits

Popular exploits related to Remote Code Execution vulnerabilities:

  1. Metasploit Framework: This is a popular penetration testing tool that includes many exploits for Remote Code Execution vulnerabilities. Metasploit can be used to develop and test exploits for a wide range of systems and applications, and provides a comprehensive set of tools for scanning, exploiting, and maintaining access to vulnerable systems.

  2. Cobalt Strike: This is a commercially available tool that is commonly used by red teams and attackers to carry out advanced attacks. Cobalt Strike includes many features for exploiting Remote Code Execution vulnerabilities, including its Beacon payload that can be used to establish a persistent backdoor on a compromised system.

  3. PowerShell Empire: This is an open-source tool that provides a powerful framework for developing and testing Remote Code Execution exploits. PowerShell Empire includes many modules for scanning, exploiting, and maintaining access to vulnerable systems, and can be customized to meet the needs of specific attack scenarios.

  4. Shellshock: This is a well-known exploit that targets the Bash shell, which is commonly used on Linux and Unix systems. The Shellshock vulnerability allows an attacker to execute arbitrary code by injecting specially crafted input into a vulnerable system.

  5. Heartbleed: This is a widely publicized vulnerability in the OpenSSL cryptographic library, which is commonly used to secure web traffic. The Heartbleed vulnerability allows an attacker to read sensitive information from a system’s memory, potentially including private keys and other credentials.

  6. EternalBlue: This is an exploit that targets a vulnerability in the SMB protocol, which is used for file sharing on Windows systems. The EternalBlue exploit was famously used in the WannaCry ransomware attack, which affected hundreds of thousands of systems around the world.

  7. Jenkins Script Console: This is a common vulnerability in the Jenkins automation server, which is widely used for software development and deployment. The Script Console vulnerability allows an attacker to execute arbitrary code on a vulnerable system by injecting commands into the Jenkins web interface.

  8. Drupalgeddon: This is a vulnerability in the Drupal content management system, which allows an attacker to execute arbitrary code by exploiting a SQL injection vulnerability. The Drupalgeddon vulnerability has been used in many high-profile attacks, including the Panama Papers leak.

  9. WordPress RevSlider: This is a vulnerability in the popular RevSlider plugin for WordPress, which allows an attacker to execute arbitrary code by exploiting a file upload vulnerability. The RevSlider vulnerability has been used in many attacks against WordPress sites, including the SoakSoak and Panama campaigns.

  10. Apache Struts: This is a popular web application framework that has been the target of many Remote Code Execution exploits. The most famous of these exploits is the Equifax data breach, which was caused by a vulnerability in the Apache Struts framework.

Practice identifying and exploiting Remote Code Execution vulnerabilities

There are several approaches that can be useful:

  1. Study relevant documentation: Start by reading up on how Remote Code Execution vulnerabilities work and the common techniques used to exploit them. The OWASP website is a great resource for learning about web application security, including Remote Code Execution vulnerabilities.

  2. Practice with vulnerable applications: There are several intentionally vulnerable web applications that you can use to practice identifying and exploiting Remote Code Execution vulnerabilities. Some popular examples include Damn Vulnerable Web Application (DVWA), WebGoat, and Mutillidae.

  3. Participate in CTF competitions: Capture the Flag (CTF) competitions are a great way to practice identifying and exploiting vulnerabilities, including Remote Code Execution vulnerabilities. Many CTF competitions focus on web application security and may include challenges related to Remote Code Execution.

  4. Use penetration testing tools: There are many penetration testing tools that can be used to identify and exploit Remote Code Execution vulnerabilities, including Metasploit, Burp Suite, and ZAP. These tools can be used to identify vulnerabilities and test different exploitation techniques.

  5. Participate in bug bounty programs: Many organizations offer bug bounty programs that provide rewards to researchers who identify and report security vulnerabilities, including Remote Code Execution vulnerabilities. Participating in these programs can provide hands-on experience with identifying and exploiting vulnerabilities in real-world applications.

Addition to practicing with Remote Code Execution vulnerabilities, there are several other security topics and practices that are worth exploring and practicing:

  1. SQL injection: SQL injection is a common web application vulnerability that can allow attackers to manipulate database queries and access sensitive data. Practicing with SQL injection vulnerabilities can help you learn how to identify and exploit these issues.

  2. Cross-site scripting (XSS): Cross-site scripting is another common web application vulnerability that can allow attackers to inject malicious scripts into web pages viewed by other users. Practicing with XSS vulnerabilities can help you learn how to identify and exploit these issues.

  3. Penetration testing methodologies: Penetration testing is a systematic approach to identifying and exploiting security vulnerabilities in systems and applications. Learning about different penetration testing methodologies and practicing with different tools can help you develop a well-rounded understanding of security testing.

  4. Web application security best practices: It’s important to understand and practice good security practices in the design and development of web applications, in order to minimize the risk of security vulnerabilities. Learning about secure coding practices, secure development methodologies, and security testing can help you build more secure applications.

  5. Network security: Network security is a broad topic that includes a range of techniques and practices for securing networks and systems. Learning about network security tools and techniques, such as firewalls, intrusion detection systems, and network segmentation, can help you better understand the broader security landscape.

Books with review of Remote Code Execution vulnerabilities

  1. “The Web Application Hacker’s Handbook: Finding and Exploiting Security Flaws” by Dafydd Stuttard and Marcus Pinto: This book is a comprehensive guide to identifying and exploiting web application vulnerabilities, including Remote Code Execution. It covers a wide range of topics, from basic web application security concepts to advanced exploitation techniques.

  2. “Black Hat Python: Python Programming for Hackers and Pentesters” by Justin Seitz: This book focuses on using the Python programming language to write tools for network penetration testing and exploitation, including Remote Code Execution. It covers a wide range of topics, from basic programming concepts to advanced network security techniques.

  3. “Web Application Security: A Beginner’s Guide” by Bryan Sullivan and Vincent Liu: This book is a beginner-friendly guide to web application security, including Remote Code Execution. It covers a wide range of topics, from basic security concepts to practical advice for securing web applications.

  4. “The Tangled Web: A Guide to Securing Modern Web Applications” by Michal Zalewski: This book is a comprehensive guide to web application security, including Remote Code Execution. It covers a wide range of topics, from web application architecture and design to common security vulnerabilities and techniques for securing web applications.

  5. “Mastering Modern Web Penetration Testing” by Prakhar Prasad: This book is a practical guide to web application penetration testing, including techniques for identifying and exploiting Remote Code Execution vulnerabilities. It covers a wide range of topics, from reconnaissance and information gathering to testing and exploitation.

List of payloads for Remote Code Execution vulnerabilities

some common payloads that can be used in Remote Code Execution attacks, along with examples:

  1. Command Injection: Attacker injects malicious commands into the system to be executed. Examples: “;cat /etc/passwd”, “|cat /etc/passwd”.

  2. Code Injection: Attacker injects malicious code to be executed by the system. Examples: “<?php system($_GET[‘cmd’]); ?>”, “{{7*7}}”.

  3. Shellcode Injection: Attacker injects shellcode to be executed by the system. Examples: \xeb\x1d\x5e\x89\x76\x08\x31\xdb\x88\x5e\x07\x89\x5e\x0c\xb0\x0b\x89\xf3\x8d\
    x4e\x08\x8d\x56\x0c\xcd\x80\xe8\xde\xff\xff\xff/bin/sh.

  4. File Upload: Attacker uploads a malicious file to the system, which can then be executed. Examples: A PHP file with a web shell that can be used to execute commands on the server, or a JSP file that can be used to execute Java code on the server.

  5. Dynamic Code Evaluation: Attacker submits code that is dynamically evaluated by the system. Examples: “eval()”, “exec()”, “system()”, “passthru()”.

  6. Cross-site Scripting (XSS): Attacker injects malicious code that is executed in a victim’s web browser. Examples: “<script>alert(‘XSS’);</script>”, “<img src=’javascript:alert(“XSS”);’>”.

Mitigations and how to be protected from Remote Code Execution vulnerabilities

  1. Input validation and sanitization: Proper input validation and sanitization of user input can help prevent malicious code from being injected and executed on a system.

  2. Output encoding: Output encoding can help prevent malicious code from being executed when output is rendered in a browser or other application.

  3. Sandbox and virtualization: Running potentially untrusted code in a sandbox or virtualized environment can limit its access to the underlying system and help prevent Remote Code Execution attacks.

  4. Use of Web Application Firewalls (WAFs): A WAF can monitor and filter incoming web traffic to prevent exploits that could lead to Remote Code Execution.

  5. Secure coding practices: Using secure coding practices such as avoiding the use of user input in system commands, using parameterized queries for database access, and avoiding the use of eval() and other similar functions can help prevent Remote Code Execution vulnerabilities in code.

  6. Application whitelisting: Whitelisting applications and processes that are allowed to run on a system can help prevent unauthorized code execution.

  7. Network segmentation: Segregating networks into smaller, isolated segments can help limit the spread of malware and attacks that exploit Remote Code Execution vulnerabilities.

  8. Patching and updating: Keeping software and systems up to date with the latest security patches and updates can help prevent known Remote Code Execution vulnerabilities from being exploited.

By implementing these mitigations, you can significantly reduce the risk of Remote Code Execution vulnerabilities on your systems.

Conclusion

Remote Code Execution (RCE) vulnerabilities are among the most dangerous and damaging types of security vulnerabilities that can affect software systems. RCE vulnerabilities can allow an attacker to run arbitrary code on a vulnerable system, which can lead to a range of serious consequences, including data theft, data destruction, and the compromise of entire networks and systems.

RCE vulnerabilities are typically caused by flaws in input validation and sanitization, which can allow an attacker to inject malicious code or commands into an application or system. These vulnerabilities can be exploited in a number of ways, including via web applications, email attachments, and other methods.

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