CVE-2025-7992

Executive Summary

CVE-2025-7992 is a high-severity (CVSS 7.8) out-of-bounds read vulnerability in Ashlar-Vellum Cobalt, a CAD/CAM software application. The flaw resides in the parsing of AR files, where insufficient validation of user-supplied data allows an attacker to read past the end of an allocated data structure. Successful exploitation requires user interaction (opening a malicious AR file or visiting a malicious page) and can lead to remote code execution in the context of the current process. No public proof-of-concept, exploit code, or patch is currently available. The vulnerability was reported via the Zero Day Initiative (ZDI-CAN-25972).

CVSS Breakdown & Threat Level

• Attack Vector (AV): Local (AV:L) – Exploitation requires the attacker to deliver a malicious file to the target system.
• Attack Complexity (AC): Low (AC:L) – No special conditions beyond user interaction.
• Privileges Required (PR): None (PR:N) – No authentication needed.
• User Interaction (UI): Required (UI:R) – Victim must open the malicious file.
• Scope (S): Unchanged (S:U) – Vulnerability does not affect other components.
• Confidentiality (C): High (C:H) – Potential memory disclosure.
• Integrity (I): High (I:H) – Code execution possible.
• Availability (A): High (A:H) – Crash or code execution.

Threat Level: High – Exploitation can lead to full compromise of the affected system, but requires user interaction.

Deep Dive & Mechanics

The vulnerability is a classic out-of-bounds read (CWE-125) in the AR file parser of Ashlar-Vellum Cobalt. AR files are a proprietary format used for CAD data. The parser fails to validate the length of user-supplied data before reading from a buffer, allowing an attacker to craft a malicious AR file that triggers a read past the end of an allocated data structure. This can lead to:

• Memory Disclosure: Leak sensitive data from adjacent memory regions.
• Code Execution: By carefully controlling the out-of-bounds read, an attacker can corrupt control flow structures (e.g., function pointers, return addresses) and achieve arbitrary code execution.

The vulnerability is triggered when the victim opens the malicious AR file in Cobalt. The attacker does not need any special privileges or network access beyond delivering the file (e.g., via email, download, or USB).

Vulnerable vs. Patched Code

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

// Vulnerable pseudo-code
void parse_AR_file(char *data, size_t size) {
    char *buffer = malloc(256);
    memcpy(buffer, data, 256); // No size check
    // ... further processing that reads beyond buffer
}

A patched version would include bounds checking:

// Patched pseudo-code
void parse_AR_file(char *data, size_t size) {
    if (size < 256) {
        // Handle error
        return;
    }
    char *buffer = malloc(256);
    memcpy(buffer, data, 256);
    // ... safe processing
}

Exploitation & Lab Setup

Red Team

Objective: Achieve remote code execution on a target running Ashlar-Vellum Cobalt.

Prerequisites:

• A malicious AR file crafted to trigger the out-of-bounds read.
• Delivery method (e.g., phishing email with attachment, malicious website).

Steps:

1. Craft Malicious AR File: Use a fuzzer or manual analysis to identify the exact offset and data that cause the out-of-bounds read. Overwrite a function pointer or return address with a controlled value.
2. Deliver Payload: Send the malicious AR file to the target via email or host it on a website.
3. Trigger Exploit: The victim opens the file in Cobalt, triggering the vulnerability and executing shellcode.

Example (Conceptual):

# Python script to generate a malicious AR file (conceptual)
import struct

# Craft data to trigger OOB read and overwrite return address
payload = b"A" * 256  # Fill buffer
payload += struct.pack("<Q", 0x4141414141414141)  # Overwrite return address
# ... additional shellcode

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

Blue Team

Detection:

• Monitor for unusual file opens of .ar files by Ashlar-Vellum Cobalt.
• Use process monitoring to detect crashes or abnormal memory access patterns.
• Deploy YARA rules to scan for malicious AR files.

Hunting:

• Search for AR files with unusually large or malformed headers.
• Correlate with user interaction events (e.g., email attachments, downloads).

Indicators of Compromise (IOCs)

• File Hashes: (No known samples yet)
• Network Indicators: None (local file-based)
• Process Anomalies: Cobalt.exe crashes or high memory access violations.
• Registry/File System: Malicious AR files with suspicious structure.

Detection Engineering

YARA Rule

rule CVE_2025_7992_Ashlar_Vellum_AR_OOB {
    meta:
        description = "Detects malicious AR files exploiting CVE-2025-7992"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-7992"
    strings:
        $magic = "AR"  // AR file magic bytes (example)
        $oob_pattern = { 41 41 41 41 41 41 41 41 }  // Example pattern
    condition:
        $magic at 0 and #oob_pattern > 5
}

Sigma Rule

title: CVE-2025-7992 Ashlar-Vellum Cobalt AR File Parsing Exploit
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2025-7992 via process crash or abnormal memory access
author: Valters IT
date: 2025-04-01
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\Cobalt.exe'
        CommandLine|contains: '.ar'
    condition: selection
falsepositives:
    - Legitimate AR file usage
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-7992 Ashlar-Vellum Cobalt AR File Download"; flow:to_client,established; file.name:"*.ar"; file.magic:"AR"; sid:1000001; rev:1;)

Remediation & Mitigation

• No Patch Available: As of now, no official patch exists. Monitor vendor updates.
• Mitigation:
  • Do not open AR files from untrusted sources.
  • Use application sandboxing or virtualization to isolate Cobalt.
  • Implement file reputation scanning for AR files.
  • Restrict execution of Cobalt to least privilege.
• Workaround: Convert AR files to a safer format before opening.

Valters IT
Securing Digital Frontiers