CVE-2024-5307

Executive Summary

CVE-2024-5307 is an information disclosure vulnerability in Kofax Power PDF, specifically within the handling of Annotation objects in AcroForms. The flaw is an out-of-bounds read (CWE-125) that can be triggered when a user opens a malicious PDF file or visits a malicious page. The vulnerability has a low CVSS score of 3.3 due to the requirement for user interaction and the limited impact (confidentiality only). No public proof-of-concept (PoC) or exploit code is currently available, and the patch status remains unknown. While the EPSS score is 0.0%, the vulnerability could be chained with other flaws to achieve arbitrary code execution, making it a concern for organizations using Kofax Power PDF in high-risk environments.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a standalone desktop application (Kofax Power PDF) and is not part of a software supply chain ecosystem.

CVSS Breakdown & Threat Level

• CVSS Score: 3.3 (Low)
• Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
• Attack Vector: Local (requires user to open a malicious file)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: None
• Availability Impact: None

Threat Level: Low. Exploitation requires user interaction and only leads to information disclosure. However, chaining with other vulnerabilities could elevate the risk.

Deep Dive & Mechanics

The vulnerability resides in the AcroForm Annotation handling component of Kofax Power PDF. When parsing a specially crafted PDF file, the application fails to properly validate user-supplied data related to Annotation objects. This leads to a read past the end of an allocated buffer (out-of-bounds read). An attacker can leverage this to read sensitive memory contents, potentially leaking data such as other PDF content, system information, or credentials.

The flaw is classified as CWE-125 (Out-of-bounds Read). The root cause is insufficient bounds checking when processing Annotation object properties. The attacker controls the PDF structure, including the Annotation dictionary, and can craft values that cause the parser to read beyond the intended buffer.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison cannot be provided. However, the vulnerable code likely resembles:

// Vulnerable pseudo-code
void processAnnotation(Annotation *ann) {
    char *data = ann->data;
    int length = ann->length;
    // No bounds check on user-controlled offset
    char value = data[user_offset]; // Out-of-bounds read
}

A patched version would include a bounds check:

// Patched pseudo-code
void processAnnotation(Annotation *ann) {
    char *data = ann->data;
    int length = ann->length;
    if (user_offset >= 0 && user_offset < length) {
        char value = data[user_offset];
    } else {
        // Handle error
    }
}

Exploitation & Lab Setup

Red Team

Objective: Exploit the out-of-bounds read to leak sensitive information from the victim's memory.

Prerequisites:

• Kofax Power PDF installed on a target system.
• Victim must open a malicious PDF file.

Steps:

1. Craft a PDF with a malformed AcroForm Annotation object. Use a PDF manipulation library (e.g., pdfminer, PyPDF2) to create a PDF with an Annotation dictionary containing an out-of-bounds offset.
2. Embed the malicious PDF in a phishing email or host it on a website.
3. When the victim opens the PDF in Kofax Power PDF, the out-of-bounds read occurs, leaking memory contents.
4. Capture the leaked data (e.g., via a side channel or by observing application behavior).

Example Malicious PDF Structure (Conceptual):

%PDF-1.4
1 0 obj
<< /Type /Catalog /Pages 2 0 R >>
endobj
2 0 obj
<< /Type /Pages /Kids [3 0 R] /Count 1 >>
endobj
3 0 obj
<< /Type /Page /Parent 2 0 R /Annots [4 0 R] >>
endobj
4 0 obj
<< /Type /Annot /Subtype /Text /Rect [0 0 100 100] /Contents (malicious) /Offset 999999 >>
endobj
xref
...
trailer
<< /Size 5 /Root 1 0 R >>
startxref
...
%%EOF

Note: No public exploit code is available. The above is a conceptual representation.

Blue Team

Detection:

• Monitor for unusual PDF files being opened, especially those with malformed Annotation objects.
• Use endpoint detection and response (EDR) tools to detect out-of-bounds read attempts (e.g., via memory access violations).
• Implement application whitelisting to restrict PDF readers to patched versions.

Mitigation:

• Disable automatic opening of PDFs from untrusted sources.
• Use a sandboxed PDF reader or a browser-based PDF viewer.
• Apply the vendor patch when available.

Indicators of Compromise (IOCs)

• File Hashes: No known malicious files.
• Network Indicators: No network-based IOCs (vulnerability is local).
• Behavioral Indicators:
  • Kofax Power PDF process (e.g., PowerPDF.exe) crashes or exhibits memory access violations.
  • Unexpected memory reads in the AcroForm Annotation handler.
• Registry/File System: No known persistence mechanisms.

Detection Engineering

YARA Rule

rule CVE_2024_5307_Kofax_PowerPDF_OOB_Read {
    meta:
        description = "Detects malicious PDFs exploiting CVE-2024-5307"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-5307"
    strings:
        $pdf_header = "%PDF"
        $annotation = "/Annot" nocase
        $offset = "/Offset" nocase
        $large_offset = /\/Offset\s+\d{6,}/  // Offset with 6+ digits
    condition:
        $pdf_header at 0 and $annotation and $offset and $large_offset
}

Sigma Rule

title: CVE-2024-5307 Kofax Power PDF Out-of-Bounds Read
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects potential exploitation of CVE-2024-5307 via process crashes or memory access violations in Kofax Power PDF.
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\PowerPDF.exe'
        CommandLine|contains: '.pdf'
    condition: selection
falsepositives:
    - Legitimate PDF files with large Annotation offsets (rare)
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-5307 Kofax Power PDF Malicious PDF Download"; flow:to_client,established; file.name:/\.pdf$/i; content:"/Annot"; content:"/Offset"; distance:0; within:100; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

1. Vendor Patch: Apply the official patch from Kofax when released. Monitor the Kofax support portal for updates.
2. Workaround: Disable AcroForm Annotation processing in Kofax Power PDF settings if possible.
3. User Awareness: Train users not to open PDFs from untrusted sources.
4. Application Control: Use application whitelisting to prevent execution of unpatched versions.
5. Sandboxing: Open PDFs in a sandboxed environment or use a browser-based PDF viewer.
6. Monitoring: Deploy the provided YARA, Sigma, and Suricata rules to detect exploitation attempts.

Valters IT
DevSecOps & Cyber Threat Intelligence