CVE-2024-5306

Executive Summary

CVE-2024-5306 is a critical memory corruption vulnerability in Kofax Power PDF, a desktop application for PDF viewing and editing. The flaw resides in the PDF file parsing component, where improper validation of user-supplied data can lead to memory corruption. An attacker can exploit this by convincing a user to open a malicious PDF file or visit a crafted web page, resulting in remote code execution (RCE) in the context of the current process. The vulnerability has a CVSS score of 7.8 (High) and is currently unpatched, with no public proof-of-concept or exploit code available. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant due to the potential for full system compromise.

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 does not involve package manager dependencies.

CVSS Breakdown & Threat Level

• CVSS Score: 7.8 (High)
• Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
• Attack Vector (AV): Local (L) – The attacker must have local access or convince the user to open a file.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – The target must open a malicious file or visit a malicious page.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components.
• Confidentiality (C): High (H) – Full data access possible.
• Integrity (I): High (H) – Full data modification possible.
• Availability (A): High (H) – Full system denial of service possible.

Threat Level: High. Although no active exploitation is reported, the vulnerability allows arbitrary code execution with user interaction, making it a prime target for phishing campaigns.

Deep Dive & Mechanics

The vulnerability is a classic memory corruption issue in the PDF parsing engine of Kofax Power PDF. When the application processes a specially crafted PDF file, it fails to validate the size or boundaries of user-supplied data, leading to a buffer overflow or use-after-free condition. This can corrupt adjacent memory, allowing an attacker to overwrite function pointers or critical data structures.

Root Cause: Lack of proper bounds checking in the PDF parsing routine. The application reads data from the PDF file without verifying that it fits within allocated buffers.

Attack Vector: Remote, but requires user interaction. An attacker can host a malicious PDF on a website or send it via email. When the user opens the file with Kofax Power PDF, the exploit triggers.

Impact: Successful exploitation grants the attacker code execution in the context of the current user. This can lead to data theft, installation of malware, or lateral movement within a network.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison is not possible. However, based on the vulnerability description, the vulnerable code likely resembles:

// Vulnerable: No bounds check
void parse_pdf_data(char *input, size_t input_len) {
    char buffer[256];
    memcpy(buffer, input, input_len); // Potential overflow
}

A patched version would include validation:

// Patched: Bounds check
void parse_pdf_data(char *input, size_t input_len) {
    char buffer[256];
    if (input_len > sizeof(buffer)) {
        // Handle error
        return;
    }
    memcpy(buffer, input, input_len);
}

Exploitation & Lab Setup

Red Team

Objective: Achieve remote code execution on a target system running Kofax Power PDF.

Prerequisites:

• Kofax Power PDF installed on a Windows system.
• User interaction (open a malicious PDF).

Steps:

1. Craft Malicious PDF: Use a fuzzer or manual manipulation to create a PDF that triggers the memory corruption. Since no public exploit exists, this requires reverse engineering the PDF parser.
2. Deliver Payload: Host the PDF on a phishing site or send via email with social engineering.
3. Trigger Exploit: When the user opens the PDF, the memory corruption overwrites a return address or function pointer, redirecting execution to shellcode.
4. Execute Shellcode: The shellcode can spawn a reverse shell, download additional malware, or exfiltrate data.

Example (Conceptual):

# Conceptual exploit script (not functional)
import struct

# Craft PDF with overflow
payload = b"A" * 256  # Fill buffer
payload += struct.pack("<I", 0xdeadbeef)  # Overwrite return address
# Add shellcode
payload += b"\x90" * 100  # NOP sled
payload += shellcode

with open("malicious.pdf", "wb") as f:
    f.write(payload)

Blue Team

Detection:

• Monitor for unusual PDF files being opened, especially from external sources.
• Use endpoint detection and response (EDR) to detect memory corruption events (e.g., access violations).
• Deploy YARA rules to scan for malicious PDFs.

Mitigation:

• Restrict execution of Kofax Power PDF in sandboxed environments.
• Use application whitelisting to prevent untrusted PDFs.
• Educate users about phishing risks.

Indicators of Compromise (IOCs)

• File Hashes: No known malicious samples yet.
• Network Indicators: Connections to unknown IPs after PDF opening.
• Process Behavior: Kofax Power PDF process (e.g., PowerPDF.exe) exhibiting crashes or abnormal memory access.
• Registry Changes: Unauthorized modifications to startup entries.
• File System: Creation of suspicious files in temp directories.

Detection Engineering

YARA Rule

rule CVE_2024_5306_Kofax_PDF_Memory_Corruption {
    meta:
        description = "Detects malicious PDFs targeting CVE-2024-5306"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-5306"
    strings:
        $pdf_header = "%PDF"
        $overflow_pattern = { 41 41 41 41 41 41 41 41 } // Pattern of 'A's
    condition:
        $pdf_header at 0 and #overflow_pattern > 10
}

Sigma Rule

title: Kofax Power PDF Memory Corruption Exploit
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2024-5306 via process crash or abnormal memory access
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 opening
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-5306 Kofax Power PDF Exploit"; flow:to_server,established; content:"%PDF"; offset:0; depth:4; content:"|41 41 41 41|"; distance:0; within:100; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

• No patch available: Monitor vendor updates for Kofax Power PDF.
• Disable or restrict the use of Kofax Power PDF until a patch is released.
• Use alternative PDF readers (e.g., Adobe Acrobat, Foxit Reader) with stricter security controls.

Long-term:

• Implement application sandboxing (e.g., Windows Defender Application Guard).
• Enable exploit protection features (e.g., ASLR, DEP, CFG).
• Conduct regular security awareness training for users.

Workaround:

• Configure Group Policy to block PDF files from being opened in Kofax Power PDF.
• Use file reputation services to scan PDFs before opening.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert