CVE-2025-11466

Executive Summary

CVE-2025-11466 is a directory traversal vulnerability in the Allegra application, specifically within the DatabaseBackupBL class. This flaw allows an authenticated remote attacker to read arbitrary files on the server by supplying a maliciously crafted path that is not properly validated before being used in file operations. The vulnerability leads to information disclosure in the context of the service account, potentially exposing sensitive configuration files, database credentials, or other proprietary data. With a CVSS score of 4.9 (Medium), the attack complexity is low, but authentication is required. No public proof-of-concept (PoC) or exploit code has been released at this time, and the vendor has not confirmed a patch.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
• Base Score: 4.9 (Medium)
• Attack Vector (AV): Network – the vulnerability can be exploited remotely.
• Attack Complexity (AC): Low – no special conditions are required.
• Privileges Required (PR): Low – an attacker must have valid credentials.
• User Interaction (UI): None – no user action is needed.
• Scope (S): Unchanged – the exploit does not affect other components.
• Confidentiality (C): Low – limited information disclosure.
• Integrity (I): None – no data modification.
• Availability (A): None – no denial of service.

Threat Level: Medium. While authentication is required, the low complexity and network-based attack vector make this a realistic threat for environments where attackers have obtained low-privilege credentials.

Deep Dive & Mechanics

The vulnerability resides in the DatabaseBackupBL class of Allegra. This class is responsible for handling database backup operations, which typically involve reading and writing files on the server. The flaw is a classic directory traversal (path traversal) issue: the application fails to sanitize user-supplied input used to construct file paths. An attacker can inject sequences like ../ to escape the intended backup directory and read arbitrary files from the filesystem.

Root Cause: The lack of proper validation of a user-supplied path prior to using it in file operations. The application likely concatenates user input with a base directory without checking for traversal sequences.

Attack Scenario:

1. An attacker authenticates to the Allegra web interface.
2. The attacker sends a crafted request to the vulnerable endpoint (e.g., /backup/download?file=../../../../etc/passwd).
3. The server reads the file and returns its contents in the response.
4. The attacker can then read sensitive files such as configuration files, database credentials, or application source code.

Impact: Information disclosure in the context of the service account. This could lead to further compromise if credentials or other sensitive data are exposed.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable pattern and the expected fix.

Vulnerable Code (Conceptual):

public string GetBackupFile(string userInput)
{
    string basePath = "C:\\Backups\\";
    string fullPath = basePath + userInput; // No validation
    return File.ReadAllText(fullPath);
}

Patched Code (Expected):

public string GetBackupFile(string userInput)
{
    string basePath = "C:\\Backups\\";
    // Sanitize input: remove path traversal sequences
    string safeInput = Path.GetFileName(userInput);
    string fullPath = Path.Combine(basePath, safeInput);
    // Ensure the final path is within the base directory
    if (!fullPath.StartsWith(basePath))
    {
        throw new SecurityException("Invalid path.");
    }
    return File.ReadAllText(fullPath);
}

The fix should use Path.GetFileName() to strip directory components and then verify that the resolved path remains within the intended directory.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Valid credentials for the Allegra application.
• Network access to the Allegra server.

Exploitation Steps:

1. Authenticate to the Allegra web interface.
2. Identify the vulnerable endpoint (likely related to database backup download).
3. Craft a request with a path traversal payload, e.g.:

   GET /backup/download?file=../../../../etc/passwd HTTP/1.1
   Host: target-allegra-server
   Cookie: session=valid_session_cookie
   

4. Observe the response containing the contents of /etc/passwd (or other sensitive files).

Example cURL Command:

curl -v -b "session=valid_session_cookie" "http://target-allegra-server/backup/download?file=../../../../etc/passwd"

Expected Output:

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
...

Blue Team (Detection & Defense)

Detection:

• Monitor web server logs for requests containing ../ or ..\\ in query parameters.
• Look for unusual file paths in backup download requests.
• Alert on repeated attempts to access files outside the expected backup directory.

Defense:

• Implement strict input validation and sanitization for all file-related parameters.
• Use a whitelist of allowed filenames instead of blacklisting traversal sequences.
• Run the application with the least privileges necessary (e.g., a dedicated service account with limited filesystem access).
• Deploy a Web Application Firewall (WAF) with rules to block path traversal attempts.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests containing ../ or ..\\ in query parameters (e.g., file=../../../../etc/passwd).
  • Unusual file paths in backup download requests (e.g., /etc/shadow, /app/config/database.yml).
• File System IOCs:
  • Unexpected access to sensitive files (e.g., /etc/passwd, /etc/shadow, application configuration files).
• Log IOCs:
  • Web server logs showing repeated attempts to access files outside the backup directory.
  • Application logs with errors related to file access or path validation.

Detection Engineering

YARA Rule

rule CVE_2025_11466_Directory_Traversal {
    meta:
        description = "Detects directory traversal attempts targeting Allegra DatabaseBackupBL"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-11466"
    strings:
        $traversal1 = "../"
        $traversal2 = "..\\"
        $traversal3 = "%2e%2e%2f"
        $traversal4 = "%2e%2e%5c"
        $param = "file="
    condition:
        any of ($traversal*) and $param
}

Sigma Rule

title: CVE-2025-11466 Directory Traversal Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects directory traversal attempts in Allegra backup download requests
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-11466
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 
            - '../'
            - '..\\'
            - '%2e%2e%2f'
            - '%2e%2e%5c'
        cs-uri-query|startswith: '/backup/download?file='
    condition: selection
falsepositives:
    - Legitimate use of relative paths in backup filenames (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-11466 Directory Traversal Attempt"; flow:to_server,established; content:"GET"; http_method; content:"/backup/download?file="; http_uri; content:"../"; distance:0; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the affected system if possible, or restrict network access to the Allegra application.
2. Review access logs for signs of exploitation.
3. Apply input validation as a temporary workaround (e.g., using a reverse proxy or WAF to block path traversal patterns).

Long-Term Fix:

• Vendor Patch: Await an official patch from Allegra. Contact the vendor for an ETA.
• Code Fix: If source code is available, implement proper path validation as described in the "Vulnerable vs. Patched Code" section.
• Upgrade: Once a patched version is released, upgrade immediately.

Compensating Controls:

• Least Privilege: Run the Allegra service with a low-privilege account that has minimal filesystem access.
• Monitoring: Enable detailed logging and alerting for file access anomalies.
• WAF: Deploy a Web Application Firewall with rules to block directory traversal attempts.

Valters IT