CVE-2026-0954

Executive Summary

CVE-2026-0954 is a critical memory corruption vulnerability in Digilent DASYLab, a data acquisition and control software. The flaw is an out-of-bounds write that occurs when the application loads a specially crafted .DSB file. Successful exploitation could lead to information disclosure or arbitrary code execution. The attack vector requires user interaction, as an attacker must convince a user to open a malicious .DSB file. As of this report, no official patch is available, and the vendor has not released a security advisory. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the severity remains high.

This vulnerability is not related to any package ecosystem (NPM, PyPI, Go, Ruby) and is a standalone desktop application issue.

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: Local (requires opening a file)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must open the file)
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The high CVSS score reflects the potential for full system compromise, though the requirement for user interaction reduces the risk of widespread automated attacks.

Deep Dive & Mechanics

The vulnerability resides in the file parsing logic of DASYLab when handling .DSB files. An out-of-bounds write occurs because the application does not properly validate the size of data read from the file before writing it to a fixed-size buffer. This is a classic buffer overflow scenario.

Technical Details:

• Root Cause: Lack of bounds checking on a memory copy operation during .DSB file parsing.
• Trigger: A specially crafted .DSB file containing a field with a length value that exceeds the allocated buffer size.
• Impact: The overflow can overwrite adjacent memory regions, including function pointers or return addresses, leading to arbitrary code execution.
• Exploitability: The attacker must craft a .DSB file that triggers the overflow. Since the file format is proprietary, reverse engineering is required to identify the vulnerable field.

Vulnerable vs. Patched Code

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

Vulnerable Code (Conceptual):

char buffer[256];
int length = read_int_from_file(file);
read_bytes_from_file(file, buffer, length); // No bounds check

Patched Code (Conceptual):

char buffer[256];
int length = read_int_from_file(file);
if (length > sizeof(buffer)) {
    // Handle error
    return -1;
}
read_bytes_from_file(file, buffer, length);

The fix would involve adding a bounds check before the memory copy operation.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Install Digilent DASYLab (any version) on a Windows VM.
2. Use a debugger (e.g., x64dbg) to analyze the file parsing routine.
3. Create a fuzzer to generate malformed .DSB files and monitor for crashes.

Exploitation Steps:

1. Identify the vulnerable field by fuzzing and crash analysis.
2. Craft a .DSB file with a malicious length value to trigger the overflow.
3. Overwrite a return address or a function pointer with a controlled value.
4. Use ROP chains or shellcode injection to execute arbitrary code.

Example Payload (Conceptual):

# Python script to generate a malicious .DSB file
import struct

# Craft a buffer overflow payload
payload = b"A" * 256  # Fill buffer
payload += struct.pack("<I", 0xdeadbeef)  # Overwrite return address

# Write to file
with open("malicious.dsb", "wb") as f:
    f.write(payload)

Blue Team (Defensive)

Detection:

• Monitor for unusual file access patterns to .DSB files.
• Use endpoint detection and response (EDR) to detect memory corruption events.
• Implement application whitelisting to prevent execution of untrusted DASYLab instances.

Mitigation:

• Restrict execution of DASYLab to trusted users only.
• Use sandboxing or virtualization for processing untrusted .DSB files.
• Educate users about the risks of opening .DSB files from unknown sources.

Indicators of Compromise (IOCs)

• File Hashes: (Example only, actual hashes will vary)
  • malicious.dsb SHA256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
• Process Behavior:
  • DASYLab.exe crashing with memory access violations.
  • Unusual child processes spawned by DASYLab.exe.
• Network Indicators:
  • Outbound connections from DASYLab.exe to unknown IPs (if exploitation leads to C2).
• Registry Changes:
  • Modifications to HKEY_CURRENT_USER\Software\Digilent\DASYLab (if persistence is attempted).

Detection Engineering

YARA Rule

rule CVE_2026_0954_Digilent_DASYLab_DSB {
    meta:
        description = "Detects malicious .DSB files exploiting CVE-2026-0954"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-0954"
    strings:
        $magic = { 44 53 42 } // "DSB" magic bytes
        $overflow = { 41 41 41 41 } // Pattern of A's indicating overflow
    condition:
        $magic at 0 and #overflow > 100
}

Sigma Rule

title: CVE-2026-0954 DASYLab Memory Corruption
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects crashes or memory corruption events in DASYLab.exe
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: 'DASYLab.exe'
        CommandLine|contains: '.dsb'
    condition: selection
falsepositives:
    - Legitimate use of DASYLab with valid .DSB files
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-0954 DASYLab Potential C2"; flow:to_server,established; content:"|00 00 00 00|"; depth:4; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Discontinue use of Digilent DASYLab until a patch is available.
2. Implement file access controls to prevent users from opening .DSB files from untrusted sources.
3. Use application sandboxing (e.g., Windows Sandbox, Sandboxie) to isolate DASYLab execution.

Long-term Solutions:

• Monitor the vendor's website for a security update.
• Consider migrating to alternative data acquisition software that is actively maintained.
• Implement a file integrity monitoring (FIM) solution to detect changes to .DSB files.

Workarounds:

• If DASYLab is critical, restrict its execution to a dedicated, isolated machine with no network access.
• Use a custom file parser to validate .DSB files before opening them in DASYLab.

Valters IT
Securing Digital Frontiers