CVE-2026-0957

Executive Summary

CVE-2026-0957 is a high-severity 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, corrupted file. Successful exploitation can lead to information disclosure or arbitrary code execution in the context of the logged-in user. The attack vector is local and requires user interaction (opening a malicious file). No public proof-of-concept (PoC) or patch is currently available, and the EPSS score is 0.0%, indicating low exploitation activity in the wild. This vulnerability poses a significant risk to industrial control system (ICS) environments where DASYLab is used for data logging and analysis.

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 – the attacker must have local access to the system or trick the user into opening a file.
• Attack Complexity (AC): Low – no special conditions are required.
• Privileges Required (PR): None – no authentication needed.
• User Interaction (UI): Required – the victim must open the malicious file.
• Scope (S): Unchanged – the exploit does not affect other components.
• Confidentiality (C): High – full disclosure of sensitive data possible.
• Integrity (I): High – arbitrary code execution can modify system state.
• Availability (A): High – crash or denial of service possible.

Threat Level: High. The vulnerability is unpatched and affects all versions of DASYLab. In ICS/SCADA environments, exploitation could lead to data theft, system compromise, or disruption of critical monitoring processes.

Deep Dive & Mechanics

The vulnerability is an out-of-bounds write (CWE-787) in the file parsing routine of Digilent DASYLab. When the application loads a .dasy or other supported file format, it fails to properly validate the size of a buffer before writing data. An attacker can craft a file with a malformed header or data block that causes the application to write beyond the allocated memory region.

Technical Details:

• The flaw likely resides in the DASYLab.exe or a supporting DLL responsible for file I/O.
• The out-of-bounds write can corrupt adjacent heap memory, leading to a crash or, with careful manipulation, arbitrary code execution.
• Since the vulnerability is triggered during file loading, it is a classic "file parsing" bug common in legacy software.
• No ASLR/DEP bypass details are available, but modern Windows mitigations may make exploitation harder.

Attack Scenario:

1. An attacker creates a malicious .dasy file with a crafted header that specifies an incorrect data length.
2. The attacker delivers the file via email, USB drive, or a compromised website.
3. The victim opens the file in DASYLab.
4. The application reads the malformed data, triggering an out-of-bounds write.
5. The attacker gains code execution in the context of the user, potentially installing malware or exfiltrating data.

Vulnerable vs. Patched Code

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

// Vulnerable pseudo-code
void LoadFile(const char* filename) {
    char buffer[256];
    FILE* f = fopen(filename, "rb");
    fread(buffer, 1, 512, f);  // No bounds check - writes beyond buffer
    // ... process data
}

A patched version would include bounds checking:

// Patched pseudo-code
void LoadFile(const char* filename) {
    char buffer[256];
    FILE* f = fopen(filename, "rb");
    size_t bytesRead = fread(buffer, 1, sizeof(buffer), f);  // Safe read
    if (bytesRead > sizeof(buffer)) {
        // Handle error
    }
    // ... process data
}

Exploitation & Lab Setup

Red Team

Objective: Achieve arbitrary code execution by crafting a malicious DASYLab file.

Lab Setup:

• Windows 10/11 VM with Digilent DASYLab installed (any version).
• Python 3.x with struct and os modules.
• Debugger: x64dbg or WinDbg.

Steps:

1. Analyze File Format: Use a hex editor to study a legitimate .dasy file. Identify the header structure and data block offsets.
2. Craft Malicious File: Create a Python script that modifies a legitimate file to include an oversized data length field.

   import struct
   import os
   
   # Read a legitimate file
   with open('legit.dasy', 'rb') as f:
       data = bytearray(f.read())
   
   # Overwrite the data length field at offset 0x10 with a large value
   # This is a hypothetical offset; actual analysis required
   struct.pack_into('<I', data, 0x10, 0xFFFFFFFF)  # Max size to trigger overflow
   
   # Write the malicious file
   with open('malicious.dasy', 'wb') as f:
       f.write(data)
   

3. Trigger Exploit: Open malicious.dasy in DASYLab. Monitor with a debugger to observe the crash at the out-of-bounds write.
4. Achieve Code Execution: Use heap spraying or ROP chains to redirect execution to shellcode. This requires detailed reverse engineering of the vulnerable function.

Note: No public exploit code is available. The above is a generic methodology.

Blue Team

Objective: Detect and prevent exploitation of CVE-2026-0957.

Detection:

• Monitor for unusual file creation/modification in directories where DASYLab files are stored.
• Use endpoint detection and response (EDR) to alert on DASYLab crashes or memory corruption events.
• Deploy application whitelisting to prevent unauthorized executables from running.

Prevention:

• Restrict user permissions to prevent installation of untrusted software.
• Use email filtering to block .dasy attachments from unknown senders.
• Implement file integrity monitoring (FIM) on critical DASYLab configuration files.

Hunting:

• Search for event logs with Application Error ID 1000 (crash) related to DASYLab.exe.
• Look for suspicious child processes spawned by DASYLab (e.g., cmd.exe, powershell.exe).

Indicators of Compromise (IOCs)

Detection Engineering

YARA Rule

rule CVE_2026_0957_Digilent_DASYLab_OutOfBoundsWrite {
    meta:
        description = "Detects malicious DASYLab files exploiting CVE-2026-0957"
        author = "Valters IT"
        date = "2025-04-10"
        hash = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
    strings:
        $header = "DASY" ascii wide nocase
        $overflow = { FF FF FF FF }  // Potential oversized length field
    condition:
        $header and #overflow > 2
}

Sigma Rule

title: CVE-2026-0957 - DASYLab File Crash
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects DASYLab crashes potentially caused by CVE-2026-0957 exploitation
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: windows
detection:
    selection:
        EventID: 1000
        Application: 'DASYLab.exe'
    condition: selection
falsepositives:
    - Legitimate crashes due to corrupted files
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-0957 - DASYLab Malicious File Download"; flow:to_server,established; content:"|44 41 53 59|"; distance:0; within:4; content:"|FF FF FF FF|"; distance:0; within:4; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate DASYLab systems: Disconnect from untrusted networks and restrict file sharing.
2. User Awareness: Train users not to open .dasy files from untrusted sources.
3. Application Control: Use AppLocker or similar to block execution of DASYLab unless explicitly needed.

Long-Term Fix:

• Monitor Digilent’s website for a security patch. If none is released, consider migrating to an alternative data acquisition software.
• Implement a virtualized environment for DASYLab to contain potential exploits.

Workaround:

• Use a file scanner that can detect malformed DASYLab files (e.g., custom YARA rules).
• Enable Windows Defender Exploit Guard (ASLR, DEP, CFG) to increase exploitation difficulty.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert