WindowsService - Security Audit¶

Executive Summary¶

The Psyter Payment Inquiry Windows Service handles sensitive payment and user data, making security a critical concern. This audit identifies 15 security vulnerabilities ranging from critical to low severity, with 5 critical issues requiring immediate attention.

Critical Findings Summary¶

Risk Score: 7.2/10 (High Risk)¶

Critical Vulnerabilities¶

VULN-001: Plaintext Database Credentials in App.config¶

Severity: 🔴 CRITICAL
Category: Authentication & Credentials
CVSS Score: 9.1 (Critical)

Issue:
Database credentials are stored in plaintext in App.config:

<connectionStrings>
  <add name="PsyterDatabase" 
       connectionString="Data Source=devdb.innotech-sa.com;
                         Initial Catalog=psyter_v1;
                         Persist Security Info=True;
                         User Id=psyter_dev;
                         Password=p$y7erDevUser26;" 
       providerName="System.Data.SqlClient"/>
</connectionStrings>

Attack Vectors:
- File system access reveals credentials
- Configuration file backup exposure
- Version control commit (if accidentally committed)
- Memory dump analysis
- Process inspection

Impact:
- Complete database compromise
- Access to all patient data
- Payment information exposure
- Ability to modify/delete records
- HIPAA/GDPR violations

Recommendation - DO NOW:

1. Use Windows DPAPI for encryption:
   

   # Encrypt connectionStrings section
   aspnet_regiis -pef "connectionStrings" "C:\Path\To\Service" -prov "DataProtectionConfigurationProvider"
   

2. Alternative: Use Windows Credential Manager:
   

   // Store credentials in Windows Credential Manager
   // Retrieve at runtime
   using System.Security.Credentials;
   var cred = CredentialManager.ReadCredential("PsyterDB");
   

3. Best Practice: Use Azure Key Vault or similar:
   

   // Retrieve from secure vault
   var secretClient = new SecretClient(vaultUri, credential);
   var password = secretClient.GetSecret("DbPassword").Value.Value;
   

Priority: P0 - Immediate

VULN-002: SSL Certificate Validation Bypass¶

Severity: 🔴 CRITICAL
Category: Network Security
CVSS Score: 8.6 (High)

Issue:
The service bypasses all SSL certificate validation:

ServicePointManager.ServerCertificateValidationCallback += 
    new RemoteCertificateValidationCallback(AllwaysGoodCertificate);

private static bool AllwaysGoodCertificate(object sender, X509Certificate certificate, 
    X509Chain chain, SslPolicyErrors policyErrors)
{
    return true;  // ALWAYS returns true!
}

Location: PaymentInquiryService.cs, line ~960

Attack Vectors:
- Man-in-the-Middle (MITM) attacks
- SSL stripping attacks
- Certificate spoofing
- Interception of payment data
- API credential theft

Impact:
- Payment gateway communication compromised
- API tokens intercepted
- Patient data exposed in transit
- Refund transactions manipulated
- Complete loss of transport security

Recommendation - DO NOW:

1. Remove callback entirely (for production):
   

   // REMOVE these lines completely
   // ServicePointManager.ServerCertificateValidationCallback += ...
   

2. For development only, use proper validation:
   

   #if DEBUG
   ServicePointManager.ServerCertificateValidationCallback += 
       (sender, cert, chain, errors) => {
           if (errors == SslPolicyErrors.None) return true;
   
           // Log the error
           WriteToFile($"SSL Error: {errors}", "Security");
   
           // Only bypass for specific known dev certificates
           return cert.Subject.Contains("devdb.innotech-sa.com");
       };
   #endif
   

3. Ensure production uses valid certificates:
   - Install proper SSL certificates on all endpoints
   - Use trusted Certificate Authorities
   - Implement certificate pinning for critical APIs

Priority: P0 - Immediate

VULN-003: Sensitive Payment Data in Log Files¶

Severity: 🔴 CRITICAL
Category: Data Exposure
CVSS Score: 8.2 (High)

Issue:
Complete payment gateway responses are logged, potentially including sensitive data:

// Line ~770
WriteToFile("Payment Gateway Response :  " + output, "Refund");
WriteToFile("Payment Gateway Response :  " + output, "Inquiry");

Data Potentially Logged:
- Response.CardHolderName - Cardholder names
- Response.CardNumber - Card numbers (even if masked)
- Response.CardExpiryDate - Expiry dates
- Response.RRN - Reference numbers
- Transaction IDs and amounts

Example Log Entry:

Payment Gateway Response: Response.StatusCode=00000&Response.CardHolderName=John Doe&Response.CardNumber=4***1234&Response.CardExpiryDate=12/25&...

Attack Vectors:
- Log file access (file system permissions)
- Log aggregation systems
- Backup files
- Forensic recovery
- Insider threats

Impact:
- PCI-DSS compliance violation
- Card data exposure
- Identity theft risk
- Regulatory penalties
- Reputational damage

Recommendation - DO NOW:

1. Sanitize before logging:
   

   private string SanitizePaymentResponse(string response)
   {
       var sanitized = response;
   
       // Redact card number (keep last 4 digits)
       sanitized = Regex.Replace(sanitized, 
           @"CardNumber=\d+", 
           "CardNumber=****");
   
       // Redact cardholder name
       sanitized = Regex.Replace(sanitized, 
           @"CardHolderName=[^&]+", 
           "CardHolderName=REDACTED");
   
       // Redact expiry date
       sanitized = Regex.Replace(sanitized, 
           @"CardExpiryDate=[^&]+", 
           "CardExpiryDate=**/**");
   
       return sanitized;
   }
   
   // Usage
   WriteToFile("Payment Gateway Response: " + SanitizePaymentResponse(output), "Inquiry");
   

2. Log only essential fields:
   

   WriteToFile($"Payment Status: {statusCode}, Transaction: {transactionId}", "Inquiry");
   

3. Implement log rotation with encryption:
   - Encrypt log files at rest
   - Secure log file permissions (Admin only)
   - Implement log retention policies

Priority: P0 - Immediate

VULN-004: API Tokens in Memory Without Protection¶

Severity: 🔴 CRITICAL
Category: Authentication & Credentials
CVSS Score: 7.8 (High)

Issue:
API access tokens stored in plaintext string fields:

protected string PsyterAPIApplicationToken = null;
protected string PsyterAPIAuthToken = null;
protected string SchedulingAPIApplicationToken = null;
protected string SchedulingAPIAuthToken = null;

Attack Vectors:
- Memory dump analysis
- Process memory inspection
- Debugger attachment
- Heap analysis tools
- Crash dumps

Impact:
- API access compromise
- Unauthorized operations
- Data manipulation
- Service impersonation

Recommendation - DO NOW:

1. Use SecureString for tokens:
   

   using System.Security;
   using System.Runtime.InteropServices;
   
   private SecureString psyterAPIAuthToken = null;
   
   private void SetToken(ref SecureString secureToken, string plainToken)
   {
       if (secureToken != null)
       {
           secureToken.Dispose();
       }
   
       secureToken = new SecureString();
       foreach (char c in plainToken)
       {
           secureToken.AppendChar(c);
       }
       secureToken.MakeReadOnly();
   }
   
   private string GetToken(SecureString secureToken)
   {
       IntPtr ptr = Marshal.SecureStringToBSTR(secureToken);
       try
       {
           return Marshal.PtrToStringBSTR(ptr);
       }
       finally
       {
           Marshal.ZeroFreeBSTR(ptr);
       }
   }
   

2. Clear tokens when not in use:
   

   protected override void OnStop()
   {
       // Clear sensitive data
       psyterAPIAuthToken?.Dispose();
       schedulingAPIAuthToken?.Dispose();
   
       WriteToFile("Service is stopped at " + DateTime.Now, "Inquiry");
   }
   

Priority: P0 - Immediate

VULN-005: No Input Validation on Database Results¶

Severity: 🔴 CRITICAL
Category: Injection & Validation
CVSS Score: 7.5 (High)

Issue:
Data from database is used directly without validation:

// Line ~780
updateBookingPayForDataObj.CardHolderName = result.ContainsKey("Response.CardHolderName") 
    ? result["Response.CardHolderName"] : null;

No validation of:
- Field length
- Character encoding
- SQL injection via stored procedures
- XSS in log files
- Command injection

Attack Vectors:
- Malicious data in database
- Compromised stored procedures
- Data injection via other services
- Log injection attacks

Impact:
- Potential code execution
- Log file corruption
- Database corruption
- System compromise

Recommendation - DO NOW:

1. Implement input validation:
   

   private string ValidateAndSanitize(string input, int maxLength = 255)
   {
       if (string.IsNullOrEmpty(input)) return null;
   
       // Trim to max length
       input = input.Substring(0, Math.Min(input.Length, maxLength));
   
       // Remove control characters
       input = Regex.Replace(input, @"[\x00-\x1F\x7F]", "");
   
       // Remove SQL injection attempts
       if (input.Contains("'") || input.Contains("--") || 
           input.Contains(";") || input.Contains("/*"))
       {
           WriteToFile($"Potential injection attempt: {input}", "Security");
           return null;
       }
   
       return input;
   }
   
   // Usage
   updateBookingPayForDataObj.CardHolderName = 
       ValidateAndSanitize(result["Response.CardHolderName"], 100);
   

2. Validate numeric fields:
   

   private decimal? ParseAmount(string input)
   {
       if (decimal.TryParse(input, out decimal result))
       {
           if (result >= 0 && result <= 999999.99m)
           {
               return result;
           }
       }
       WriteToFile($"Invalid amount: {input}", "Security");
       return null;
   }
   

Priority: P0 - Immediate

High Severity Vulnerabilities¶

VULN-006: Weak Thread Management Security¶

Severity: 🟠 HIGH
Category: Concurrency & Race Conditions
CVSS Score: 6.8 (Medium)

Issue:
Thread state checking without synchronization:

if (RefundAndInquiryThread == null)
{
    RefundAndInquiryThread = new Thread(() => GetPendingPayment());
    RefundAndInquiryThread.Start();
}
else
{
    if (!RefundAndInquiryThread.IsAlive)
    {
        // Race condition here!
        RefundAndInquiryThread = new Thread(() => GetPendingPayment());
        RefundAndInquiryThread.Start();
    }
}

Attack Vectors:
- Race conditions
- Double processing
- Resource exhaustion
- Deadlocks

Impact:
- Duplicate payment processing
- Duplicate refunds
- Data corruption
- Service instability

Recommendation - DO NEXT:

private readonly object threadLock = new object();

public void CreateThread()
{
    lock (threadLock)
    {
        if (RefundAndInquiryThread == null || 
            !RefundAndInquiryThread.IsAlive)
        {
            RefundAndInquiryThread = new Thread(() => GetPendingPayment());
            RefundAndInquiryThread.Name = "RefundAndInquiryThread";
            RefundAndInquiryThread.Start();
        }
    }
}

Priority: P1

VULN-007: No API Rate Limiting or Throttling¶

Severity: 🟠 HIGH
Category: DoS & Resource Exhaustion
CVSS Score: 6.5 (Medium)

Issue:
No rate limiting on API calls or payment gateway requests.

Attack Vectors:
- API quota exhaustion
- Payment gateway throttling
- Service degradation
- Cost overruns

Impact:
- API account suspension
- Service disruption
- Financial penalties
- Data loss

Recommendation - DO NEXT:

using System.Collections.Concurrent;

private ConcurrentDictionary<string, DateTime> apiCallHistory = 
    new ConcurrentDictionary<string, DateTime>();

private bool CanMakeApiCall(string apiName, int maxCallsPerMinute = 10)
{
    var now = DateTime.UtcNow;
    var key = $"{apiName}_{now.ToString("yyyyMMddHHmm")}";

    if (apiCallHistory.TryGetValue(key, out DateTime lastCall))
    {
        var callCount = apiCallHistory.Count(x => 
            x.Key.StartsWith(apiName) && 
            (now - x.Value).TotalMinutes < 1);

        if (callCount >= maxCallsPerMinute)
        {
            WriteToFile($"Rate limit exceeded for {apiName}", "Security");
            return false;
        }
    }

    apiCallHistory[key] = now;
    return true;
}

Priority: P1

VULN-008: No Encryption for Data in Transit (Internal)¶

Severity: 🟠 HIGH
Category: Network Security
CVSS Score: 6.3 (Medium)

Issue:
Database connection may not use encryption:

<connectionString>Data Source=devdb.innotech-sa.com;...

No Encrypt=True or TrustServerCertificate specified.

Impact:
- Database traffic interception
- Credential theft
- Data exposure

Recommendation - DO NEXT:

<connectionString>
  Data Source=devdb.innotech-sa.com;
  Initial Catalog=psyter_v1;
  User Id=psyter_dev;
  Password=[ENCRYPTED];
  Encrypt=True;
  TrustServerCertificate=False;
</connectionString>

Priority: P1

VULN-009: Insufficient Error Information in Logs¶

Severity: 🟠 HIGH
Category: Logging & Monitoring
CVSS Score: 5.8 (Medium)

Issue:
Generic exception handling without detailed logging:

catch (Exception ex)
{
    WriteToFile("Exception occur " + DateTime.Now + ", Error: " + ex.Message, "Inquiry");
}

Missing Information:
- Stack traces
- Inner exceptions
- Context data
- Request parameters (sanitized)

Impact:
- Difficult troubleshooting
- Security incident detection delays
- Incomplete audit trails

Recommendation - DO NEXT:

private void LogException(Exception ex, string context, string logType)
{
    var sb = new StringBuilder();
    sb.AppendLine($"[{DateTime.UtcNow:O}] EXCEPTION in {context}");
    sb.AppendLine($"Message: {ex.Message}");
    sb.AppendLine($"Type: {ex.GetType().FullName}");
    sb.AppendLine($"Stack Trace: {ex.StackTrace}");

    if (ex.InnerException != null)
    {
        sb.AppendLine($"Inner Exception: {ex.InnerException.Message}");
        sb.AppendLine($"Inner Stack: {ex.InnerException.StackTrace}");
    }

    WriteToFile(sb.ToString(), logType);
}

// Usage
catch (Exception ex)
{
    LogException(ex, "GetPendingPayment", "Inquiry");
}

Priority: P1

Medium Severity Vulnerabilities¶

VULN-010: No Secure Hash Validation¶

Severity: 🟡 MEDIUM
Category: Cryptography
CVSS Score: 5.5 (Medium)

Issue:
No validation of payment gateway response signatures.

Recommendation - PLAN:
Verify response secure hash before processing.

Priority: P2

VULN-011: Lack of Audit Trail for Security Events¶

Severity: 🟡 MEDIUM
Category: Logging & Monitoring
CVSS Score: 5.2 (Medium)

Issue:
No dedicated security event logging.

Recommendation - PLAN:
Implement security event log with:
- Authentication attempts
- Authorization failures
- Data access patterns
- Configuration changes

Priority: P2

VULN-012: No Service Account Privilege Restrictions¶

Severity: 🟡 MEDIUM
Category: Access Control
CVSS Score: 5.0 (Medium)

Issue:
Service likely runs under LocalSystem or Admin account.

Recommendation - PLAN:
- Create dedicated service account
- Grant minimal required permissions
- Remove admin rights

Priority: P2

VULN-013: XML Injection Risk in Database Updates¶

Severity: 🟡 MEDIUM
Category: Injection
CVSS Score: 4.8 (Medium)

Issue:
XML serialization without validation:

var xml = XmlHelper.ObjectToXml(updateBookingPayForDataObj);
dataBase.AddInParameter(dbCommand, "@PaymentData", DbType.Xml, xml);

Recommendation - PLAN:
Validate XML schema before database submission.

Priority: P2

Low Severity Issues¶

VULN-014: Hardcoded Timer Intervals¶

Severity: 🟢 LOW
Category: Configuration Management
CVSS Score: 2.5 (Low)

Issue:
Timer intervals hardcoded:

timer.Interval = 600000;  // 10 minutes

Recommendation - PLAN:
Move to configuration file.

Priority: P3

VULN-015: No Code Obfuscation¶

Severity: 🟢 LOW
Category: Reverse Engineering
CVSS Score: 2.0 (Low)

Issue:
Compiled binaries can be easily decompiled.

Recommendation - PLAN:
Consider using obfuscation tools for sensitive logic.

Priority: P3

Compliance Issues¶

PCI-DSS Violations¶

1. Requirement 3.4: Card data in logs (VULN-003)
2. Requirement 4.1: SSL bypass (VULN-002)
3. Requirement 8.2: Plaintext credentials (VULN-001)

HIPAA Violations¶

1. §164.312(a)(1): Insufficient access controls (VULN-004)
2. §164.312(e)(1): Data in transit not encrypted (VULN-008)
3. §164.308(a)(1): No security event logging (VULN-011)

GDPR Concerns¶

1. Article 32: Inadequate data security (VULN-001, 003, 004)
2. Article 32(1)(b): No encryption (VULN-008)
3. Article 33: Insufficient breach detection (VULN-011)

Remediation Roadmap¶

Phase 1: Immediate (Week 1)¶

Priority: P0

• VULN-001: Encrypt database credentials
• VULN-002: Remove SSL bypass
• VULN-003: Sanitize log output
• VULN-004: Secure token storage
• VULN-005: Add input validation

Phase 2: Short-term (Weeks 2-3)¶

Priority: P1

• VULN-006: Fix thread synchronization
• VULN-007: Implement rate limiting
• VULN-008: Enable database encryption
• VULN-009: Improve error logging

Phase 3: Medium-term (Month 2)¶

Priority: P2

• VULN-010: Validate response signatures
• VULN-011: Security event logging
• VULN-012: Service account hardening
• VULN-013: XML validation

Phase 4: Long-term (Month 3)¶

Priority: P3

• VULN-014: Configurable intervals
• VULN-015: Code obfuscation

Total Remediation Effort: ~81 hours (~10 days)

Security Best Practices Recommendations¶

1. Secrets Management¶

• Use Azure Key Vault, AWS Secrets Manager, or HashiCorp Vault
• Rotate credentials regularly (90 days)
• Use managed identities where possible

2. Network Security¶

• Implement IP whitelisting for database
• Use VPN for service-to-service communication
• Enable SQL Server firewall rules

3. Monitoring & Alerting¶

• Implement SIEM integration
• Set up anomaly detection
• Monitor failed authentication attempts
• Alert on suspicious payment patterns

4. Incident Response¶

• Create incident response plan
• Define escalation procedures
• Implement automated service isolation
• Regular security drills

5. Code Security¶

• Regular security code reviews
• Automated vulnerability scanning
• Dependency vulnerability checks
• Penetration testing annually

Audit Date: November 10, 2025
Auditor: AI Security Analyst
Risk Level: High (7.2/10)
Compliance Status: Non-Compliant (PCI-DSS, HIPAA, GDPR)
Recommended Actions: Immediate remediation of P0 issues