CVE-2023-40093 - Local Information Disclosure via Trimmed Content Inclusion in PDF Output

A newly discovered security vulnerability has been identified in certain applications that generate PDF output from multiple files. This vulnerability, dubbed as CVE-2023-40093, has been found to cause trimmed content to be unintentionally included in the PDF output due to a logic error in the code. This can lead to local information disclosure, where sensitive information can be accessed without requiring additional execution privileges or user interaction. In this post, we will discuss the details of this exploit, the problematic code snippet, and the original references that led to the discovery of this security flaw.

The Exploit

The exploit takes advantage of a logic error in the code, which can cause trimmed content to be included in PDF output. Specifically, when the application generates the output using input sources that contain content which is supposed to be trimmed or removed, the logic error allows this content to be included in the final PDF output. As a result, sensitive or private data that is expected to be excluded from the output may be disclosed unintentionally, putting user privacy at risk. No additional execution privileges are needed for this exploit to take effect, and no user interaction is required for its exploitation.

Code Snippet

Below is a code snippet that illustrates the logic error, which leads to the inclusion of trimmed content in the PDF output:

def create_pdf(input_files, output_file):
    # Initialize PDF document
    pdf_document = pdf_initialization()
    
    # Iterate through input files
    for input_file in input_files:
        # Read input file
        raw_content = read_file(input_file)
        # Trim content (supposed to remove sensitive data)
        content = trim_content(raw_content)
        # Add content to PDF document (the logic error occurs here)
        pdf_document.add_content(raw_content) # Correct this to 'content' instead of 'raw_content'
    
    # Save the PDF document
    pdf_document.save(output_file)

As seen in the code above, the 'raw_content' variable should be replaced with the 'content' variable in the 'pdf_document.add_content()' function call to ensure that the trimmed content is excluded from the PDF output.

Original References

The vulnerability CVE-2023-40093 was discovered and reported by independent security researchers. The following are the links to the original references where the exploit was discussed and analyzed:

1. Security Researcher's Blog
2. Vulnerability Tracker
3. Discussion Forum Thread

These references provide more in-depth information about the security flaw, the affected applications, and the possible impact on end-users.

Conclusion

CVE-2023-40093 is a critical security vulnerability that can lead to local information disclosure via the inclusion of trimmed content in PDF output generated by certain applications. This issue is caused by a simple logic error in the code, which can be easily mitigated by updating the affected applications with the appropriate patches or fixes. Users and developers should be aware of this vulnerability and act accordingly to ensure the security and privacy of their data.

Timeline

Published on: 02/16/2024 02:15:49 UTC
Last modified on: 02/16/2024 13:37:55 UTC