CVE-2024-5511

Executive Summary

CVE-2024-5511 is a high-severity (CVSS 7.8) remote code execution vulnerability in Kofax Power PDF, a widely used document processing application. The flaw resides in the parsing of JP2 (JPEG 2000) image files, where an out-of-bounds read occurs due to insufficient validation of user-supplied data. Successful exploitation requires user interaction—the victim must open a malicious JP2 file or visit a crafted web page. An attacker can leverage this to execute arbitrary code in the context of the current process, potentially leading to full system compromise. No public exploit or patch details are currently available, and the EPSS score is 0.0%, indicating low active exploitation in the wild.

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) – Requires the attacker to have local access or trick the user into opening a file.
• Attack Complexity (AC): Low (L) – No special conditions required beyond user interaction.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – Victim must open a malicious file or page.
• Scope (S): Unchanged (U) – Exploitation does not affect other components.
• Confidentiality (C): High (H) – Full data access possible.
• Integrity (I): High (H) – Code execution allows modification of data.
• Availability (A): High (H) – Potential for denial of service or system takeover.

Threat Level: High. While no active exploitation is reported, the vulnerability is critical due to the potential for arbitrary code execution in a widely used enterprise application.

Deep Dive & Mechanics

The vulnerability is an out-of-bounds read (CWE-125) in the JP2 file parsing component of Kofax Power PDF. JP2 files are based on the JPEG 2000 standard, which uses a complex box-based structure. The specific flaw occurs when the parser reads data from a JP2 file without properly validating the length of allocated buffers. By crafting a JP2 file with malformed box headers or truncated data, an attacker can cause the parser to read beyond the end of an allocated object, potentially leaking sensitive memory or, more critically, corrupting adjacent memory structures.

This out-of-bounds read can be leveraged for remote code execution by carefully controlling the memory layout. For example, the read may overwrite function pointers or return addresses, leading to arbitrary code execution. The vulnerability is triggered during normal file processing, making it a classic "user-assisted" exploit vector.

Vulnerable vs. Patched Code

No patched version is available. The vulnerable code likely resides in the JP2 parsing library (e.g., JP2Parser.dll or similar). A hypothetical fix would involve adding bounds checks before memory reads:

Vulnerable (pseudocode):

void parse_jp2_box(uint8_t *data, size_t size) {
    uint32_t box_length = *(uint32_t*)data; // No validation
    // ... read box_length bytes from data
    process_box(data, box_length); // Out-of-bounds if box_length > size
}

Patched (pseudocode):

void parse_jp2_box(uint8_t *data, size_t size) {
    if (size < 4) return; // Minimum header size
    uint32_t box_length = *(uint32_t*)data;
    if (box_length > size) return; // Bounds check
    process_box(data, box_length);
}

Exploitation & Lab Setup

Red Team (Exploitation)

1. Craft Malicious JP2 File: Use a hex editor or custom script to create a JP2 file with an oversized box length field. For example, set the first 4 bytes to a value larger than the actual file size.
2. Deliver Payload: Host the file on a web server or send via email. The victim must open it in Kofax Power PDF.
3. Trigger Exploit: When the victim opens the file, the out-of-bounds read occurs. If memory is carefully arranged (e.g., via heap spraying), this can lead to code execution.

Example Python script to generate a malicious JP2 file:

import struct

def create_malicious_jp2():
    # Minimal JP2 file with oversized box length
    box_length = 0xFFFFFFFF  # Max value to trigger OOB read
    box_type = b'jp2h'       # Example box type
    data = b'A' * 100        # Dummy data
    file_content = struct.pack('>I', box_length) + box_type + data
    with open('malicious.jp2', 'wb') as f:
        f.write(file_content)

create_malicious_jp2()

Blue Team (Detection & Defense)

• User Awareness: Train users not to open JP2 files from untrusted sources.
• Application Control: Use AppLocker or similar to restrict Kofax Power PDF execution.
• Memory Protection: Enable ASLR, DEP, and CFG to mitigate exploitation.
• Network Filtering: Block JP2 file downloads from suspicious domains.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (None available publicly; generate upon discovery)
• Network Traffic: HTTP/HTTPS downloads of .jp2 files from untrusted origins.
• Process Behavior: Kofax Power PDF (e.g., PowerPDF.exe) crashing or exhibiting abnormal memory access patterns.
• Registry/File System: Temporary files in %TEMP% with .jp2 extension.

Detection Engineering

YARA Rule

rule CVE_2024_5511_JP2_OOB_Read {
    meta:
        description = "Detects malicious JP2 files exploiting CVE-2024-5511"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-5511"
    strings:
        $jp2_header = { 00 00 00 0C 6A 50 20 20 } // JP2 file signature
        $large_box = { FF FF FF FF } // Oversized box length
    condition:
        $jp2_header at 0 and $large_box
}

Sigma Rule

title: CVE-2024-5511 Kofax Power PDF JP2 Parsing Exploit
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to exploit CVE-2024-5511 via malicious JP2 files
author: Valters IT
date: 2025-04-10
logsource:
    category: file_event
    product: windows
detection:
    selection:
        Image|endswith: '\PowerPDF.exe'
        TargetFilename|endswith: '.jp2'
    condition: selection
falsepositives:
    - Legitimate JP2 files from trusted sources
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-5511 Kofax Power PDF JP2 Download"; flow:to_client; file.name:/\.jp2$/i; content:"|00 00 00 0C 6A 50 20 20|"; distance:0; within:8; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

• Patch Status: No official patch available. Monitor vendor advisories.
• Mitigation:
  • Disable JP2 file support in Kofax Power PDF if possible.
  • Use a sandbox or virtualized environment to open untrusted PDFs.
  • Implement application whitelisting to prevent unauthorized code execution.
  • Deploy endpoint detection and response (EDR) solutions with behavioral analysis.
• Workaround: Convert JP2 files to a safer format (e.g., PNG) before opening.

Valters IT
DevSecOps & Cyber Threat Intelligence
Securing digital ecosystems through proactive defense.