CVE-2022-4645 - LibTIFF 4.4. Out-of-bounds Read Vulnerability Analysis and Exploit Details

LibTIFF is a popular software library that provides support for reading, writing, and manipulating Tagged Image File Format (TIFF) files. Over the years, LibTIFF has seen widespread adoption in various applications, including image editing software, document management systems, and more.

Recently, a new vulnerability was discovered in LibTIFF 4.4., which could allow an attacker to cause a denial-of-service attack via a crafted TIFF file. Assigned CVE-2022-4645, this vulnerability is an out-of-bounds read in the tiffcp utility found within the tools/tiffcp.c source file. This blog post aims to provide an in-depth analysis of the vulnerability, detailing the relevant code snippet, exploit details, and links to the original references.

Code Snippet

The affected code in question is found in tools/tiffcp.c on line 948. Listed below is the relevant code snippet:

...
    for (i = ; i < (td_imagewidth + 7) >> 3; i++) {
        uint32 k;
        uint32 bitcount;
        bitcount = MIN(xbyte, (uint32)((td_imagewidth - 1) - (i << 3))+1);
        for (k = ; k < bitcount; k++) {
            /* Process bit data */
            ...
        }
        if (i != ((td_imagewidth + 7) >> 3)-1) {
            /* Reading beyond the allocated buffer */
            xbyte = s->SeekProc(s->data, 1, SEEK_CUR); // line 948
        }
    }
...

In this code snippet, td_imagewidth is an integer representing the image width in pixels. The variable xbyte represents the current byte being read from the input TIFF file. The loop iterates over the bits of the image. However, during this loop, there is a condition that reads beyond the allocated buffer, causing an out-of-bounds read.

Original References and Fix

The vulnerability was first reported on GitLab, and you can find the complete discussion and analysis at the following link:

- GitLab issue: Out-of-bounds read in tiffcp

The LibTIFF developer team has already provided a fix for this vulnerability in commit e8131125, which can be found at the following link:

- GitLab commit: Fixed an OOB read in tiffcp

For users who compile LibTIFF from sources, the fix is available with commit e8131125. It is strongly recommended to update to this commit or a later version that includes the fix to protect against potential exploits targeting this vulnerability.

Exploit Details

To exploit this vulnerability, an attacker could create a malicious TIFF file with crafted width and bit data, which, when opened in an application utilizing the vulnerable LibTIFF library, would trigger the out-of-bounds read. As a result, it would cause an application crash, effectively creating a denial-of-service condition.

The risk of this vulnerability is that an attacker may use it as part of a larger attack, possibly in combination with other known vulnerabilities, to target affected applications and systems.

Conclusion

CVE-2022-4645 is a critical out-of-bounds read vulnerability in LibTIFF 4.4.. It is essential to update your LibTIFF installation to commit e8131125 or a later version that includes the fix to protect your applications and systems from potential exploits.

Remember that keeping your software up to date is one of the best practices you can follow to maintain the security and stability of your applications and systems.

Timeline

Published on: 03/03/2023 16:15:00 UTC
Last modified on: 03/31/2023 11:15:00 UTC