CVE-2025-57774

Executive Summary

CVE-2025-57774 is a critical out-of-bounds write vulnerability in Digilent DASYLab, affecting all versions of the software. The flaw resides in the parsing of DSB (DASYLab binary) files, where improper bounds checking allows an attacker to write invalid data beyond allocated memory boundaries. Successful exploitation requires user interaction—opening a specially crafted DSB file—and can lead to arbitrary code execution in the context of the DASYLab process. With a CVSS score of 7.8, this vulnerability poses a significant risk to industrial control, data acquisition, and engineering environments where DASYLab is used. No public proof-of-concept or patch is currently available, making awareness and detection critical.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It affects a standalone desktop application (Digilent DASYLab) distributed via vendor channels. Supply chain risk is limited to the integrity of DSB files exchanged within engineering teams or downloaded from untrusted sources.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Local (L) – Requires opening a malicious file.
• Attack Complexity (AC): Low (L) – No special conditions needed.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – Victim must open the file.
• Scope (S): Unchanged (U) – Exploit stays within the vulnerable component.
• Confidentiality (C): High (H) – Potential data exfiltration.
• Integrity (I): High (H) – Arbitrary code execution can modify system state.
• Availability (A): High (H) – Crash or full compromise possible.

Threat Level: Critical. The lack of a patch and the potential for code execution in industrial environments elevates the risk.

Deep Dive & Mechanics

The vulnerability is an out-of-bounds write (CWE-787) triggered during the parsing of DSB files. DASYLab uses a proprietary binary format to store measurement configurations, signal processing chains, and data. When loading a DSB file, the parser reads various fields (e.g., channel counts, buffer sizes, or string lengths) without validating them against allocated buffer boundaries.

Root Cause: The parser likely uses a fixed-size stack or heap buffer for temporary data (e.g., a 256-byte array for a channel name) but reads a length field from the file that can exceed this size. The code then copies user-controlled data into the undersized buffer, overwriting adjacent memory.

Attack Vector: An attacker crafts a DSB file with a malformed field (e.g., an oversized string length or an invalid array index). When the victim opens the file, the parser writes beyond the buffer, corrupting critical data structures (e.g., function pointers, return addresses, or heap metadata). This can be leveraged to redirect execution to attacker-controlled shellcode.

Impact: Arbitrary code execution with the privileges of the DASYLab process. In typical deployments, this may allow the attacker to install malware, exfiltrate measurement data, or pivot to other systems on the industrial network.

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical fix is shown below. The vulnerable code uses a fixed-size buffer without length validation:

// VULNERABLE CODE
void parse_channel_name(FILE *fp, char *buffer) {
    uint16_t name_len;
    fread(&name_len, 2, 1, fp);  // Read length from file
    fread(buffer, 1, name_len, fp);  // No bounds check - OOB write!
    buffer[name_len] = '\0';
}

A patched version would validate the length against the buffer size:

// PATCHED CODE
#define MAX_CHANNEL_NAME 256
void parse_channel_name(FILE *fp, char *buffer) {
    uint16_t name_len;
    fread(&name_len, 2, 1, fp);
    if (name_len >= MAX_CHANNEL_NAME) {
        // Handle error: reject file or truncate
        name_len = MAX_CHANNEL_NAME - 1;
    }
    fread(buffer, 1, name_len, fp);
    buffer[name_len] = '\0';
}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Environment:

• Windows 10/11 VM with DASYLab (any version) installed.
• Python 3.x with struct module for crafting DSB files.
• Debugger (x64dbg or WinDbg) for analysis.

Exploitation Steps:

1. Reverse Engineer DSB Format: Use a hex editor to analyze a benign DSB file. Identify fields like channel count, buffer sizes, and string lengths.
2. Craft Malicious File: Create a Python script that modifies a benign DSB file, setting a string length field to a large value (e.g., 0xFFFF) and filling the payload with shellcode.
3. Trigger Vulnerability: Open the crafted DSB file in DASYLab. The parser will overflow a buffer, overwriting a function pointer or return address.
4. Achieve Code Execution: Use a ROP chain or direct shellcode injection to execute a calc.exe payload or a reverse shell.

Example Python Snippet (Conceptual):

import struct

def craft_malicious_dsb(input_file, output_file, shellcode):
    with open(input_file, 'rb') as f:
        data = bytearray(f.read())
    # Assume offset 0x100 is a string length field
    # Overwrite with large value and append shellcode
    struct.pack_into('<H', data, 0x100, len(shellcode))
    data[0x102:0x102+len(shellcode)] = shellcode
    with open(output_file, 'wb') as f:
        f.write(data)

Blue Team (Defensive)

Detection & Response:

• Monitor for abnormal DASYLab process behavior (e.g., spawning cmd.exe, network connections).
• Use application whitelisting to prevent execution of untrusted DSB files.
• Deploy endpoint detection rules (see Sigma/YARA below).
• Isolate DASYLab hosts from critical networks if possible.

Mitigation Steps:

• Disable automatic file opening in DASYLab.
• Train users to only open DSB files from trusted sources.
• Use file integrity monitoring to detect modifications to DSB files.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (Placeholder – generate upon discovery)
  • e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (example)
• Network Indicators:
  • Outbound connections from DASYLab.exe to unknown IPs (port 80/443 or custom ports).
• Process Indicators:
  • DASYLab.exe spawning cmd.exe, powershell.exe, or rundll32.exe.
  • Unusual memory regions with RWX permissions in DASYLab process.
• File Indicators:
  • DSB files with abnormally large size (>10 MB) or unexpected structure.
  • Temporary files created in %TEMP% with .exe or .dll extensions.

Detection Engineering

YARA Rule

rule CVE_2025_57774_DASYLab_OOB_Write {
    meta:
        description = "Detects malicious DSB files exploiting CVE-2025-57774"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-57774"
    strings:
        $dsb_magic = { 44 53 42 00 }  // "DSB\0" magic bytes
        $large_len = { FF FF }        // Potential oversized length field
    condition:
        $dsb_magic at 0 and for any of ($large_len) : (uint16be(@) > 1024)
}

Sigma Rule

title: CVE-2025-57774 DASYLab Out-of-Bounds Write Exploitation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects suspicious child processes spawned by DASYLab.exe
author: Valters IT
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\DASYLab.exe'
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
            - '\rundll32.exe'
    condition: selection
falsepositives:
    - Legitimate administrative tasks (rare)
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-57774 DASYLab Potential C2 Beacon"; flow:to_server; content:"|00 00 00 00|"; depth:4; offset:0; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Auto-Open: Configure DASYLab to not automatically load DSB files on startup.
2. User Awareness: Train users to avoid opening DSB files from untrusted sources (email attachments, downloads).
3. Network Segmentation: Isolate DASYLab hosts from the internet and critical OT networks.

Long-Term Fix:

• Contact Digilent for an official patch. If unavailable, consider migrating to an alternative data acquisition platform.
• Implement application-level sandboxing (e.g., Windows Defender Application Guard) to contain exploits.

Workaround:

• Use a file scanner to pre-validate DSB files for anomalous structures (e.g., oversized fields). A simple Python script can check for suspicious length values.

Valters IT
Securing Industrial Environments, One CVE at a Time.