CVE-2025-57775

Executive Summary

CVE-2025-57775 is a critical heap-based buffer overflow vulnerability in Digilent DASYLab, affecting all versions of the software. The flaw resides in the parsing of DSB (DASYLab Sheet Binary) files, where improper bounds checking allows an attacker to trigger a heap overflow by crafting a malicious DSB file. Successful exploitation requires user interaction (opening the file) and can lead to arbitrary code execution in the context of the DASYLab process. The vulnerability has a CVSS score of 7.8 (High) and currently has no known patch or public exploit code. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant for targeted attacks.

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 deliver a file to the victim.
• 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) – vulnerability does not affect other components.
• Confidentiality (C): High (H) – full data compromise possible.
• Integrity (I): High (H) – arbitrary code execution.
• Availability (A): High (H) – potential for denial of service or full system compromise.

Threat Level: High. The vulnerability is unpatched and allows arbitrary code execution with minimal user interaction. While no public exploits exist, the attack vector is straightforward for targeted phishing campaigns.

Deep Dive & Mechanics

The vulnerability is a heap-based buffer overflow (CWE-122) in the DSB file parser of DASYLab. DSB files are binary files used to store measurement configurations and data. The parser fails to validate the size of user-supplied data before copying it into a heap-allocated buffer. An attacker can craft a DSB file with an oversized field, causing the parser to write beyond the allocated buffer. This overwrites adjacent heap metadata or other data structures, potentially leading to code execution.

Root Cause: The parser uses a fixed-size buffer for a specific field (e.g., a string or array) without checking the actual length from the file. When the file contains a value larger than the buffer, a heap overflow occurs.

Attack Vector: The attacker sends a malicious DSB file via email, download, or removable media. The victim opens the file in DASYLab, triggering the overflow. The attacker can then execute arbitrary code, such as installing malware, exfiltrating data, or pivoting to other systems.

Impact: Full compromise of the victim's machine, including data theft, ransomware deployment, or use as a foothold in a larger network.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is the current implementation. A patched version would include bounds checking before memory copy operations.

Vulnerable Code (Conceptual):

void parse_dsb_field(FILE *file, char *buffer, size_t buffer_size) {
    // Read field length from file (no validation)
    uint32_t field_length;
    fread(&field_length, sizeof(field_length), 1, file);
    
    // Direct copy without checking buffer_size
    fread(buffer, field_length, 1, file); // Heap overflow if field_length > buffer_size
}

Patched Code (Conceptual):

void parse_dsb_field(FILE *file, char *buffer, size_t buffer_size) {
    uint32_t field_length;
    fread(&field_length, sizeof(field_length), 1, file);
    
    // Validate field length against buffer size
    if (field_length > buffer_size) {
        // Handle error, truncate, or reject
        return;
    }
    
    fread(buffer, field_length, 1, file);
}

Exploitation & Lab Setup

Red Team

Objective: Achieve arbitrary code execution via a malicious DSB file.

Lab Setup:

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

Exploit Development Steps:

1. Analyze the DSB format: Use a hex editor to understand the structure. Identify the vulnerable field (e.g., a string field with a length prefix).
2. Craft a malicious DSB: Create a file where the length field is set to a large value (e.g., 0x1000) and the data field contains shellcode or a ROP chain.
3. Trigger the overflow: Open the file in DASYLab. The overflow overwrites heap metadata, potentially allowing control of the instruction pointer.
4. Bypass mitigations: Use heap spraying or ROP to bypass ASLR and DEP. For example, overwrite a function pointer with a gadget that jumps to shellcode.

Example Python Script (Conceptual):

import struct

# Craft a malicious DSB file
def create_malicious_dsb():
    # DSB header (simplified)
    header = b'DSB\x00'
    # Vulnerable field: length = 0x1000, data = shellcode
    field_length = 0x1000
    shellcode = b'\x90' * 0x100  # NOP sled + actual shellcode
    # Pad to field_length
    payload = shellcode + b'A' * (field_length - len(shellcode))
    
    with open('malicious.dsb', 'wb') as f:
        f.write(header)
        f.write(struct.pack('<I', field_length))
        f.write(payload)

create_malicious_dsb()

Note: This is a conceptual example. Actual exploitation requires reverse engineering the exact DSB format and heap layout.

Blue Team

Detection & Response:

• Monitor for DSB files: Use file integrity monitoring (FIM) to detect creation of DSB files from untrusted sources.
• User awareness: Train users not to open DSB files from unknown senders.
• Application whitelisting: Block DASYLab from executing unless explicitly allowed.
• Heap overflow detection: Use tools like Microsoft's Application Verifier to detect heap corruptions in DASYLab.

Hunting Queries:

• Windows Event Logs: Look for process crashes (Event ID 1000) related to DASYLab.exe.
• Sysmon: Monitor for DASYLab.exe creating child processes (Event ID 1) or loading unexpected DLLs (Event ID 7).

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (Placeholder – generate after crafting a real exploit)
  • malicious.dsb: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
• Network Indicators: Outbound connections from DASYLab.exe to unknown IPs (if shellcode calls back).
• Process Indicators: DASYLab.exe spawning cmd.exe, powershell.exe, or other suspicious processes.
• Registry Changes: Modifications to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run for persistence.
• File System: Creation of files in %TEMP% or %APPDATA% by DASYLab.exe.

Detection Engineering

YARA Rule

rule CVE_2025_57775_DSB_HeapOverflow {
    meta:
        description = "Detects malicious DSB files exploiting CVE-2025-57775"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-57775"
    strings:
        $dsb_header = "DSB" ascii wide
        $large_length = { FF FF 00 00 } // Example: length > 0xFFFF
    condition:
        $dsb_header at 0 and $large_length
}

Sigma Rule

title: Suspicious DASYLab Process Behavior
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential exploitation of CVE-2025-57775 via abnormal DASYLab process activity
author: Valters IT
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\DASYLab.exe'
        CommandLine|contains:
            - 'cmd.exe'
            - 'powershell.exe'
            - 'wscript.exe'
    condition: selection
falsepositives:
    - Legitimate use of scripting by DASYLab (rare)
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"CVE-2025-57775 DASYLab DSB File Download"; flow:to_server,established; content:"DSB"; within:4; fileext:"dsb"; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable DSB file association: Remove the default association of .dsb files with DASYLab to prevent accidental opening.
2. User education: Warn users about phishing emails containing DSB files.
3. Network controls: Block DSB file attachments at email gateways (e.g., using file extension filtering).

Long-term Fix:

• Vendor patch: Await an official patch from Digilent. Contact their support for updates.
• Workaround: If possible, use alternative software for data acquisition until a patch is released.
• Compile from source: If source code is available, apply the bounds-checking fix and recompile.

Compensating Controls:

• Application Control: Use AppLocker or Windows Defender Application Control to allow only trusted executables.
• Heap Protection: Enable Windows Defender Exploit Guard (e.g., Set-ProcessMitigation -Enable HeapTerminateOnCorruption).
• Sandboxing: Run DASYLab in a sandboxed environment (e.g., Windows Sandbox or Sandboxie).

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert