CVE-2025-57777

Executive Summary

CVE-2025-57777 is a critical out-of-bounds write vulnerability in Digilent DASYLab, affecting all versions of the software. The flaw resides in the displ2.dll module when parsing specially crafted DSB (DASYLab Sheet Binary) files. Due to improper bounds checking, an attacker can trigger a memory corruption that may lead to arbitrary code execution in the context of the logged-on user. The attack vector requires user interaction—the victim must open a malicious DSB file, typically delivered via phishing or social engineering. With a CVSS score of 7.8, this vulnerability poses a significant risk to industrial control, data acquisition, and laboratory environments where DASYLab is deployed. No public proof-of-concept or patch is currently available, making detection and mitigation critical.

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 or trick the user into opening a file.
• Attack Complexity (AC): Low – No special conditions required beyond file parsing.
• Privileges Required (PR): None – No authentication needed.
• User Interaction (UI): Required – Victim must open the malicious DSB file.
• Scope (S): Unchanged – Exploitation does not cross trust boundaries.
• Confidentiality (C): High – Full data exposure possible.
• Integrity (I): High – Arbitrary code execution allows system modification.
• Availability (A): High – Potential for denial of service or full compromise.

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

Deep Dive & Mechanics

The vulnerability is a classic out-of-bounds write (CWE-787) in the displ2.dll library, which handles the parsing of DSB files. DSB files are binary project files used by DASYLab to store measurement configurations, display settings, and data. The flaw occurs when the parser reads a specific field (likely a length or offset value) without validating it against the allocated buffer size. An attacker can craft a DSB file with an oversized or negative value, causing the parser to write data beyond the intended buffer boundaries.

Technical Flow:

1. DASYLab loads a DSB file via displ2.dll.
2. The parser reads a user-controlled length field from the file.
3. Without proper bounds checking, the parser uses this length to copy data into a stack or heap buffer.
4. The write operation overflows the buffer, corrupting adjacent memory.
5. An attacker can control the overflow data to overwrite critical structures (e.g., return addresses, function pointers) and achieve arbitrary code execution.

Potential Attack Scenarios:

• Phishing Campaign: Attacker sends a malicious DSB file via email, disguised as a measurement configuration.
• USB Drop: Malicious DSB file placed on a shared drive or USB stick in a lab environment.
• Supply Chain: Compromised DSB file distributed through legitimate channels.

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical fix would involve adding bounds checking before memory copy operations in displ2.dll. Below is a conceptual comparison.

Vulnerable Code (C-like pseudocode):

void parse_dsb_field(char *buffer, int field_length) {
    char local_buf[256];
    // No bounds check - vulnerable
    memcpy(local_buf, buffer, field_length);
}

Patched Code (Hypothetical):

void parse_dsb_field(char *buffer, int field_length) {
    char local_buf[256];
    if (field_length > sizeof(local_buf)) {
        // Handle error, reject file
        return;
    }
    memcpy(local_buf, buffer, field_length);
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• DASYLab installed (any version).
• Ability to craft a malicious DSB file.

Exploitation Steps:

1. Craft Malicious DSB: Use a hex editor or custom script to modify a legitimate DSB file. Overwrite a length field (e.g., at offset 0x100) with a large value (e.g., 0xFFFF).
2. Trigger Overflow: The overflow data should overwrite a return address or SEH handler. For example, set the overflow payload to point to a shellcode address.
3. Deliver File: Send the DSB file to the victim via email or shared drive.
4. Execute: When the victim opens the file in DASYLab, the overflow triggers, executing arbitrary code.

Example Payload Structure (Hex):

[Header] [Length: 0xFFFF] [Overflow Data: 0x90 * 200 + Shellcode]

Note: No public exploit code is available. This is a conceptual guide.

Blue Team (Defensive)

Detection & Prevention:

• User Awareness: Train users not to open DSB files from untrusted sources.
• File Scanning: Use antivirus/EDR with behavioral analysis to detect anomalous DASYLab process behavior.
• Application Control: Restrict DASYLab execution to authorized users only.
• Sandboxing: Run DASYLab in a sandboxed environment or with reduced privileges.
• Network Segmentation: Isolate DASYLab hosts from critical networks.

Indicators of Compromise (IOCs)

• File Hashes (Malicious DSB): (None public; generate upon discovery)
• Process Anomalies: DASYLab.exe or displ2.dll crashing with access violations.
• Memory Artifacts: Large heap allocations or stack corruption in displ2.dll.
• Network Connections: Unexpected outbound connections from DASYLab process (post-exploitation).
• Registry/File Changes: New autorun entries or DLL side-loading artifacts.

Detection Engineering

YARA Rule

rule CVE_2025_57777_DSB_Malicious {
    meta:
        description = "Detects malicious DSB files exploiting CVE-2025-57777"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2025-57777"
    strings:
        $dsb_header = "DSB" ascii wide nocase
        $overflow_len = { FF FF 00 00 } // Example large length field
    condition:
        $dsb_header at 0 and $overflow_len
}

Sigma Rule

title: DASYLab DSB File Parsing Exploit
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential exploitation of CVE-2025-57777 via DASYLab crash or memory corruption
author: Valters IT
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: 'DASYLab.exe'
        CommandLine|contains: '.dsb'
    condition: selection
falsepositives:
    - Legitimate DSB file parsing
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-57777 DASYLab DSB Exploit Attempt"; flow:to_server; content:"DSB"; offset:0; depth:3; content:"|FF FF 00 00|"; within:1024; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable DSB File Association: Prevent automatic opening of DSB files in DASYLab.
2. User Training: Educate users on phishing risks and DSB file safety.
3. Monitor Logs: Watch for DASYLab crashes or unusual process behavior.

Long-Term Fixes:

• Vendor Patch: Await an official patch from Digilent. Contact support for updates.
• Workaround: Use alternative data acquisition software if possible.
• Memory Protection: Enable ASLR, DEP, and CFG on DASYLab hosts.

Valters IT Signature This report was generated by Valters IT Cyber Threat Intelligence. For questions, contact threatintel@valtersit.com.