CVE-2022-25885 is a security vulnerability affecting the well-known PDF manipulation libraries, muhammara (before v2.6.) and all versions of package hummus. These widely-used libraries enable developers to create, edit, and parse PDF files in various applications.

This vulnerability poses significant risk, as it opens the door to potential Denial of Service (DoS) attacks. Exploiting this vulnerability requires supplying a crafted PDF with invalid data to the targeted application, ultimately leading to application crashes or extended unresponsiveness.

In this blog post, we delve deeper into the specifics of this vulnerability and walk through the technical details, including proof-of-concept, code snippets, and links to original references.

Proof of Concept

The vulnerability occurs when the PDFStreamForResponse() function is used with malformed or intentionally invalid PDF data. This can lead to an uncaught exception, causing the application to crash or freeze.

Here is a demonstration of an example code snippet that triggers the vulnerability when the 'malicious.pdf' file is used as input:

const hummus = require('hummus');
const fs = require('fs');
const path = require('path');

const inputFile = 'malicious.pdf';
const outputFile = 'output.pdf';

const pdfWriter = hummus.createWriterToModify(new hummus.PDFRStreamForFile(inputFile), new hummus.PDFStreamForResponse(outputFile));
const objectsContext = pdfWriter.getObjectsContext();
const xobjectForm = pdfWriter.createXObject(objectsContext);

objectsContext.end();
pdfWriter.end();

When executed with a malicious input file, this code snippet can lead to a DoS. Note that the actual input file content is not provided here, as it is a security risk.

Original References

1. CVE-2022-25885 on the National Vulnerability Database (NVD)
2. GitHub Issue related to the vulnerability discovered in the muhammara library
3. Official Muhammara repository
4. Official Hummus repository

Exploit Details

To exploit this vulnerability, an attacker must craft a specific malformed PDF file by leveraging the vulnerability within the libraries. An attacker could then use social engineering tactics or other methods to persuade a user or administrator to load the malicious PDF file into the vulnerable application.

Upon successful exploitation, it can result in system crashes, application freezes, or other undesirable effects which can disrupt normal operations. It also puts stress on the underlying infrastructure and consumes system resources. This can lead to potential service downtime, disrupted business operations, and reputation damage.

Mitigation

Users of the affected libraries are strongly encouraged to update their package dependencies to the latest version, particularly for muhammara users who should upgrade to version 2.6. or above. For hummus users, it is advised to monitor the repository for updates related to this vulnerability, considering it affects all versions.

Upgrade using npm

npm install muhammara@^2.6.

It is also crucial that the applications explicitly handle exceptions when using PDFStreamForResponse() and other functions from these libraries to mitigate the risk.

Conclusion

CVE-2022-25885 is a serious vulnerability affecting widely-used PDF manipulation libraries. This issue can lead to impactful DoS attacks, resulting in system crashes, application freezes, and more. It is crucial for affected developers and users to update their package dependencies and ensure their applications are properly handling exceptions to protect against potential exploits targeting this vulnerability.

Timeline

Published on: 11/01/2022 05:15:00 UTC
Last modified on: 11/01/2022 19:20:00 UTC