CVE-2021-34055: Critical Buffer Overflow Vulnerability Found in jhead 3.06 - Put16u Function in exif.c

A critical security vulnerability (CVE-2021-34055) has been identified in the jhead 3.06, a popular tool for working with the Exif metadata typically found in JPEG image files. This vulnerability has the potential to lead to a Buffer Overflow attack, allowing unintended access to system resources and enabling unauthorized users to execute malicious code.

Details

The Buffer Overflow vulnerability was discovered in the Put16u function in exif.c file of jhead version 3.06. The source of the vulnerability stems from the jhead's implementation of writing Exif data in the Put16u function, which doesn't correctly account for buffer size when writing Exif data. As a result, this leads to a Buffer Overflow, causing the application to crash or potentially allowing an attacker to execute arbitrary code on the affected system.

Here's a code snippet from the vulnerable Put16u function in the exif.c file

/* Code snippet from exif.c in jhead 3.06 */
void Put16u(void * Short, unsigned short value){
    if (MotorolaOrder){
        ((uchar *)Short)[] = (unsigned char)(value >> 8);
        ((uchar *)Short)[1] = (unsigned char)value;
    }else{
        ((uchar *)Short)[] = (unsigned char)value;
        ((uchar *)Short)[1] = (unsigned char)(value >> 8);
    }
}

As you can see, there is no proper boundary check for Short, which can lead to a Buffer Overflow vulnerability.

Exploit Details

By crafting a specially designed image with malicious Exif metadata, an attacker can exploit CVE-2021-34055 to induce a Buffer Overflow in the Put16u function, subsequently leading to a crash or possible arbitrary code execution.

Original References

1. jhead 3.06 Source code: https://www.sentex.ca/~mwandel/jhead/
2. Official CVE description: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-34055

Mitigation

As of now, there is no official patch or update available from the jhead developers to address this vulnerability. It is recommended that users who rely on jhead 3.06 for processing Exif metadata should keep an eye out for updates from the developers and apply patches once they become available.

Conclusion

The discovery of CVE-2021-34055 highlights the importance of thorough code review and security testing for widely used tools like jhead. Developers and users must remain vigilant to address security vulnerabilities promptly, ensuring that attackers cannot exploit them.

Timeline

Published on: 11/04/2022 17:15:00 UTC
Last modified on: 02/03/2023 19:50:00 UTC