Secure Development & Data Protection
Security and GDPR-aware design are built in from the start — not bolted on at the end. I build bespoke .NET web systems and Android apps with practical controls aligned to OWASP guidance and real-world SME risk.
The aim: reduce risk and protect data without making the system hard to use for staff or customers.
OWASP-aligned
Secure-by-default patterns for web and APIs (plus mobile considerations where relevant).
Access control
Least privilege, role-based access, strong auth options, and sensible session handling.
Data protection
Data minimisation, retention rules, export/SAR support, and secure logging.
Auditability
Traceability for sensitive actions, change history where needed, and incident-ready logs.
What “OWASP-aligned” means in practice
OWASP publishes widely-used guidance on common web and API risks. I use it as a baseline, then apply controls proportionate to your system (users, data sensitivity, integrations, and hosting).
Common risks I actively design against
- Broken access control (users seeing or editing data they shouldn’t)
- Injection issues (SQL injection and other unsafe interpreter use)
- XSS (scripts injected into pages or admin portals)
- CSRF (tricking a logged-in user into performing actions)
- Authentication/session weaknesses (poor password handling, weak tokens)
- Insecure direct object references (guessable IDs / missing authorisation checks)
- Misconfiguration (debug settings, permissive headers, weak TLS, open storage)
- Logging gaps (no audit trail) and logging leaks (sensitive data in logs)
A lightweight approach that works for SMEs
- Identify your key data sets (customers, staff, payments, documents, special category data)
- Map where data flows (forms, APIs, integrations, mobile devices, emails, exports)
- Agree controls that are realistic (permissions, retention, MFA, backups, monitoring)
- Deliver the essentials early (auth, access control, input validation, logging)
- Keep improving with each release (dependency updates, review of new features)
How I prevent the “usual suspects”
- Use parameterised queries and safe query composition (ORM / query builders where appropriate)
- Validate and constrain inputs (IDs, paging, sorting, filtering) before they reach the database
- Apply least privilege database permissions (apps don’t run as db_owner)
- Protect admin/reporting endpoints (these are common weak spots)
- Rely on framework output encoding by default; avoid “raw HTML” unless explicitly sanitised
- Sanitise rich text inputs (when the business actually needs rich formatting)
- Use sensible security headers (e.g. CSP where feasible, plus anti-sniffing / framing controls)
- Pay special attention to admin portals and internal tools (high-value targets)
- Enable anti-forgery protections on state-changing requests
- Use SameSite cookies and safe session patterns
- Prefer token-based APIs for mobile/app-to-server flows where appropriate
- Review “dangerous” actions (payments, approvals, permissions, exports) for extra safeguards
- Secure password storage using modern hashing (never plaintext)
- Optional MFA for admin/privileged users
- Rate limiting and lockout controls to reduce brute force risk
- Secure session timeouts, token rotation, and careful “remember me” behaviour
Android and mobile app security
Mobile introduces extra considerations: devices get lost, networks are untrusted, and data can end up cached on-handset. If your system includes an Android app, I design the app + API together so they’re secure as a whole.
On-device data protection
- Minimise what’s stored locally; avoid caching personal data “just because”
- Secure storage for tokens/credentials where required (no secrets hard-coded in the app)
- Clear rules for offline mode: what’s available offline, for how long, and how it syncs
- Consider “remote logout” / token revocation for compromised devices
API security for mobile
- Strong authentication for app-to-server calls, with short-lived tokens where appropriate
- Input validation on the API (never trust the client)
- Rate limiting and monitoring on sensitive endpoints
- Consistent authorisation checks (every endpoint, every time)
GDPR-aware design for bespoke systems
I’m not a law firm — but I build systems in a way that helps you meet UK GDPR obligations in a sensible, auditable way. That usually means designing for clarity: what data you hold, why you hold it, who can access it, and how long it’s kept.
Access & accountability
- Role-based access control and least privilege
- Audit trails for sensitive actions (exports, deletions, permission changes, approvals)
- Admin tools designed to avoid accidental disclosure (e.g. safe search and masking where appropriate)
Retention, deletion & export
- Retention rules implemented in SQL Server (and documented)
- Practical support for data export / subject access requests
- Deletion and “right to erasure” workflows where appropriate (including soft-delete vs hard-delete choices)
- Logging that is useful for incidents but doesn’t leak sensitive data
Secure hosting & operational basics
Many security issues aren’t “code” problems — they’re configuration and operational gaps. I help ensure the basics are covered:
- HTTPS everywhere with modern TLS and certificate management
- Secure configuration (no debug mode, locked-down admin endpoints, careful error handling)
- Backups with tested restore, plus sensible disaster recovery planning
- Monitoring/alerting for availability and suspicious patterns (proportionate to the system)
- Regular framework and dependency updates to reduce known vulnerabilities
FAQ
Do I need a “penetration test”?
Sometimes. For many SME systems, a targeted security review plus fixing the high-risk areas gives the best ROI. For higher-risk systems (public portals, payments, sensitive data), a pen test can be a sensible next step once the foundations are sound.
Will this slow down development?
Done properly, no — it prevents rework. Secure patterns (access control, validation, logging) are easier to build in early than retrofit after launch.
Security review for an existing system
If you have a legacy web app, database, or Android app and you’re concerned about security, I can perform a targeted review and provide a prioritised list of improvements — focusing on high-impact, high-probability risks first.