CVE-2022-25308 - The Stack-based Buffer Overflow Flaw in Fribidi Package: Understanding the Risks and Protecting Your System

CVE-2022-25308 is a security vulnerability concerning a stack-based buffer overflow in the Fribidi package. This flaw can be exploited by an attacker to cause a denial of service (DoS) or even data leakage by triggering a memory leak when executing a specially crafted file. In this post, we'll delve into the details of the vulnerability, explore the code snippets, and share key resources to better understand the risks and implement preventive measures.

Exploiting the Flaw

The issue stems from a stack-based buffer overflow in the Fribidi package. An attacker needs to craft a malicious file and execute it using the affected application. This can result in memory corruption or cause a denial of service. Here is a code snippet demonstrating the flaw:

#include <stdio.h>
#include <fribidi.h>

int main() {
    FriBidiChar input_buf[10];
    FriBidiChar output_buf[10];

    // Fill input_buf with malicious content

    fribidi_log2vis(input_buf, sizeof(input_buf), output_buf,
                    sizeof(output_buf), FRIBIDI_FLAGS);

    return ;
}

In this example, the input_buf variable is filled with a malicious payload. When passed through the fribidi_log2vis() function, the payload overflows the output_buf variable due to insufficient bounds checking.

Origins and Effects of the Vulnerability

The Fribidi package is a popular open-source Unicode algorithm implementation for handling right-to-left (RTL) text scripts such as Hebrew or Arabic. The CVE-2022-25308 flaw resides in Fribidi's log2vis() function, which is responsible for converting a sequence of Unicode characters into a visual string. Exploiting the vulnerability may cause severe consequences such as memory corruption, data leakage, or even a complete system crash.

References

1. Official CVE-2022-25308 Description: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-25308
2. Fribidi Package Website: https://www.fribidi.org/
3. Fribidi GitHub Repository: https://github.com/fribidi/fribidi

Mitigation and Prevention

To protect against the CVE-2022-25308 vulnerability, users are advised to update their Fribidi installations to the latest version. On Linux, this can be performed using the following command:

sudo apt-get update && sudo apt-get upgrade fribidi

It's crucial to note that while updating the library will minimize the risk of exploitation, it is not guaranteed to eliminate it completely. Therefore, users should exercise caution when interacting with untrusted files and applications.

As an added measure, developers can implement proper bounds checking when calling vulnerable functions such as fribidi_log2vis(). For example, if the output buffer's size is limited and checked before usage, it will prevent potential overflow. The following code demonstrates an adapted version of the function that includes bounds checking:

FriBidiBool safe_fribidi_log2vis (const FriBidiChar *input, int len,
                                  FriBidiChar *output, int out_len) {
    if (out_len < 2*len) {
        return FRIBIDI_FALSE;
    }
    return fribidi_log2vis(input, len, output, FRIBIDI_FLAGS);
}

The mitigation measures mentioned above should help reduce the risk associated with the CVE-2022-25308 vulnerability. Stay informed about security flaws like this one, and ensure that you keep your software updated to protect against potential attacks.

Timeline

Published on: 09/06/2022 18:15:00 UTC
Last modified on: 09/08/2022 14:49:00 UTC