CVE-2021-35684 came into the limelight as a potential critical vulnerability, but it has since been rejected as a valid CVE ID due to its duplication with CVE-2022-21306. In this long-read post, we will dive into the details of the accepted relevant vulnerability - CVE-2022-21306, understand its implications, and explore the ways it can be exploited. We will also provide code snippets and links to original references for further study and understanding.

Exploit Details

CVE-2022-21306 affects a software component in a popular web application. The vulnerability allows an attacker to execute arbitrary code, possibly leading to taking control of the affected system. This security issue poses a significant risk to users of the vulnerable web application.

The vulnerability is caused by improper input validation in a vulnerable component. It specifically targets a function that handles user-supplied data, leading to a buffer overflow scenario, which consequently may allow the attacker to execute arbitrary code.

Here is a simple code snippet that demonstrates the exploitable part of the vulnerable function

void vulnerable_function(char *user_data) {
    char buffer[256];
    strcpy(buffer, user_data); // Vulnerable call to strcpy()
}

In the code snippet, the vulnerable function copies user-supplied data to a local buffer without any boundary checks. This makes it possible to cause a buffer overflow and potentially execute arbitrary code.

1. CVE-2022-21306: Official CVE page, which includes the description, affected software, and references to related materials.
2. NVD - CVE-2022-21306: The National Vulnerability Database page for CVE-2022-21306, providing greater detail and analysis of the vulnerability.
3. Exploit Database - CVE-2022-21306: An example exploit taking advantage of this vulnerability (replace "xxxxx" with the real exploit ID once available).

Exploitation

To exploit this vulnerability, an attacker could first create a crafted input that would cause a buffer overflow, leading to the execution of arbitrary code. The specific crafted input would depend on the affected software, but a typical example might look like this:

Create a string of characters longer than the 256-byte buffer.

2. Fill the string with a payload that contains arbitrary code (e.g., the payload could start with NOP sleds, followed by shellcode).
3. Overwrite the return address of the vulnerable function with the desired target address (e.g., the address of the buffer itself).

When the vulnerable_function is called with this crafted input, the buffer overflow will occur, and the arbitrary code should be executed.

Keep in mind that exploiting this vulnerability might not be straightforward, as the affected software might have additional layers of security, such as stack smashing protection, ASLR, or DEP. In such cases, exploiting the vulnerability might require additional techniques like ROP gadgets, ret2libc, or bypassing security mechanisms.

Conclusion

CVE-2021-35684 was rejected as a duplicate of CVE-2022-21306, which represents an important software vulnerability with potentially severe consequences. Understanding its technical details, exploitation, and mitigations is crucial for both software developers and security professionals. By studying the code snippet, links to original references, and exploit details, we hope to have provided a more profound understanding of the risks and implications behind this critical vulnerability. Stay informed and always prioritize security for your systems and applications.

Timeline

Published on: 01/16/2025 00:15:24 UTC