SaaS App Security: OWASP Threats, 5 Core Practices, Dev Effort & Cost Guide

In this guide, we list the most common security threats and break down five essential software security practices that every SaaS product should implement early including how much development work they require, what they cost, and how to approach implementation. From authentication and access control to encryption and infrastructure hardening, these foundational security measures help protect your app, your users, and your business.

Why Security Is Critical in the Modern Web and Cloud?

• Increased Attack Surface

Cloud-native apps rely on APIs, microservices, and distributed systems, all of which are exposed to the internet and vulnerable to attack.

• Shared Responsibility Model

In cloud environments (AWS, Azure, GCP), security is shared: the provider secures the infrastructure, but you must secure your code, configs, and data.

• Rapid Deployment = Higher Risk

CI/CD pipelines and frequent releases make it easy to ship insecure code without proper review, scanning, or testing.

• Data Is a Prime Target

Applications handle sensitive data (user info, financials, health records). A breach can mean millions in damages and permanent reputation loss.

• Compliance and Legal Risk

Regulations like GDPR, HIPAA, SOC 2 require strong security practices. Non-compliance leads to fines and legal action.

Most Common & Dangerous Security Threats (OWASP TOP 10)

The OWASP Foundation, a globally recognized non-profit dedicated to improving software security, identifies and regularly updates the most critical web application security threats through its widely referenced OWASP Top 10 list.

1. Injection Attacks (e.g., SQL Injection, Command Injection)

What it is: Injection attacks occur when an attacker sends malicious input to manipulate a software application into executing unintended commands or database queries.

Why it's dangerous: Injection vulnerabilities can lead to severe consequences, including unauthorized access, data breaches, and complete destruction or exposure of critical databases.

Some tips on how to prevent injection attacks in software applications:

1. Implement Parameterized Queries (Prepared Statements): Always separate user input from executable code to prevent the application from treating input as part of the command.
2. Apply Strict Input Validation and Whitelisting: Enforce accepted input patterns (such as email addresses, date formats, and numerical ranges) to minimize the risk of malicious input.
3. Use ORM (Object-Relational Mapping) Frameworks: Tools like Django ORM, SQLAlchemy, or Entity Framework help developers avoid manual query building and reduce exposure to SQL injection vulnerabilities.

2. Broken Authentication & Session Management

What it is: Broken authentication and session management refers to weaknesses in login systems, session handling, and token management: such as poorly implemented login flows, insecure storage of session tokens, or improper cookie configurations.

Why it's dangerous: These vulnerabilities can enable attackers to hijack user sessions, impersonate legitimate users, and escalate privileges. Common issues like session ID reuse or insecure storage of JWTs (JSON Web Tokens) can lead to full account compromise.

How to prevent the risk of broken authentication and insecure session management:

1. Adopt secure and standardized authentication protocols like OAuth 2.0, OpenID Connect, SAML, or managed services such as Firebase Authentication.
2. Enforce strong password policies to ensure complexity and prevent brute-force attacks.
3. Implement multi-factor authentication (MFA) to add an extra layer of security beyond just passwords.
4. Limit failed login attempts and implement account lockout mechanisms to defend against credential stuffing and brute-force attacks.

3. Sensitive Data Exposure

What it is: Sensitive data exposure refers to the failure to adequately protect confidential information such as passwords, credit card numbers, personal identifiers, and medical records during storage, transmission, or processing.

Why it's dangerous: When exposed, sensitive data can be exploited for identity theft, financial fraud, or sold on the dark web—leading to serious legal, financial, and reputational damage.

Common causes: This vulnerability often stems from insecure data storage (e.g., unencrypted S3 buckets), the use of weak or outdated encryption algorithms, or logging sensitive information in plain text.

Ways to prevent sensitive data exposure in software systems:

1. Enforce HTTPS with TLS 1.2 or higher to secure data in transit.
2. Classify sensitive data and apply strong encryption algorithms (such as AES-256) to protect it both in transit and at rest.
3. Encrypt data at rest using secure key management practices to prevent unauthorized access if infrastructure is compromised.
4. Minimize data collection and retention by only storing necessary information and securely deleting data that’s no longer required.

4. Security Misconfigurations (Especially in the Cloud)

What it is: Security misconfigurations occur when systems, applications, or cloud infrastructure are left with insecure default settings, unnecessary open ports, overly permissive IAM roles, or publicly accessible admin interfaces.

Why it's dangerous: These misconfigurations provide easy attack surfaces and are among the most common vulnerabilities, especially in cloud environments where mismanaged resources can be quickly exploited.

How to handle and prevent security misconfigurations:

• Establish secure default configurations for all software, services, and environments before deployment.
• Utilize security configuration management tools to automate scanning and enforcement of hardened configurations.
• Apply the Principle of Least Privilege (PoLP): Grant users and services only the minimum permissions necessary to function.
• Configure secure HTTP headers and web server settings to protect against common web vulnerabilities and information leakage.
• Ensure consistent security configurations across all environments including development, QA, and production to avoid gaps during deployment or testing.

5. Broken Access Control

What it is: Broken access control occurs when users are able to access resources, data, or functions that should be restricted—leading to unauthorized actions like horizontal or vertical privilege escalation.

Why it's dangerous: These vulnerabilities can allow attackers or regular users to perform actions beyond their intended permissions—such as accessing other users’ private data, modifying records, or even acting as administrators.

How to prevent broken access control in software systems:

1. Deny access by default: Users should only be granted permissions explicitly based on their role or context.
2. Implement robust Role-Based Access Control (RBAC) or Attribute-Based Access Control (ABAC): Clearly define roles (e.g., admin, user, guest) and associate them with precise permission sets.
3. Never rely solely on client-side access controls: Always enforce access control checks on the server side to prevent manipulation.
4. Secure resource and URL handling: Ensure users cannot access unauthorized endpoints or modify query parameters to bypass restrictions.
5. Enforce authorization checks on every backend request: Validate permissions for each operation on the server, regardless of the client interface.

6. Cross-Site Scripting (XSS)

What it is: Cross-Site Scripting (XSS) is a web security vulnerability where attackers inject malicious JavaScript or HTML code into web pages that are viewed by other users, often via input fields, URLs, or stored content.

Why it's dangerous: XSS attacks can steal session cookies, hijack user accounts, manipulate the DOM, or perform actions on behalf of users without their consent—leading to serious breaches in confidentiality and user trust.

Types of XSS attacks:

1. Stored XSS: Malicious script is permanently stored on the server (e.g., in a comment field) and served to users.
   
2. Reflected XSS: Script is reflected off a URL or input parameter and executed immediately in the browser.
   
3. DOM-based XSS: Script execution results from insecure manipulation of the DOM by client-side JavaScript.

How to prevent Cross-Site Scripting in web applications:

• Escape output contextually: Properly escape dynamic content based on where it appears (HTML, JavaScript, attributes, etc.).
• Use trusted templating engines or frameworks that automatically escape output (e.g., React, Angular, Handlebars).
• Validate and sanitize all user inputs: Ensure inputs conform to expected formats and remove any potentially dangerous code.
• Implement a strong Content Security Policy (CSP): Restrict where scripts can be loaded from and reduce the impact of XSS attacks.
• Avoid inline JavaScript and event handlers: Keep JavaScript separate from HTML to reduce exposure to injection points.

7. XML External Entities (XXE)

What it is: A trick where hackers sneak hidden instructions into XML files (a type of data format), which your app reads and trusts.

Why it's dangerous: These hidden instructions can make your app leak private files, crash, or send requests to places it shouldn’t.

How to prevent it:

• Turn off the part of your software that follows outside links or files in XML.
• Use newer, safer tools that don’t allow this kind of trick by default.
• If you don’t need to use XML, choose safer formats like JSON.
• Always double-check and clean any data the app receives from users.
• Set up rules and limits so even if something slips through, it can’t cause too much harm.

8. Insecure Deserialization

What it is: Letting your app unpack and trust complex data from users. In other words it's like a gift box that might have something harmful inside.

Why it's dangerous: Hackers can tamper with the data so that when your app opens it, it runs harmful commands or gives them access to private stuff.

How to prevent Insecure Deserialization:

• Avoid deserializing data from untrusted sources whenever possible.
• Use secure formats like JSON instead of binary serialization when possible.
• Validate and sanitize incoming data before deserializing it.
• Use serialization libraries that support secure deserialization or provide strict type controls.
• Implement logging and monitoring to detect deserialization attempts or anomalies.

9. Insecure Dependencies / Supply Chain Attacks

What it is: Using outdated, vulnerable, or malicious third-party libraries and packages in your software.

Why it's dangerous: Attackers exploit trusted components to infiltrate your system, often without direct access to your code.

How to prevent insecure dependencies:

1. Install packages only from official and trusted package managers.
2. Lock dependency versions to avoid unexpected or malicious updates.
3. Use automated vulnerability scanning tools regularly.
4. Remove unused, deprecated, or unmaintained packages promptly.

10. Lack of Logging and Monitoring

What it is: Not keeping track of or noticing unusual behavior or problems in your software and systems.

Why it's dangerous: If you don’t catch problems early by watching for warning signs, attackers can quietly cause damage for months without anyone knowing.

Security Logging and Monitoring Best Practices:

• Log all critical security events, including user authentication, authorization failures, privilege changes, and system access.
• Implement centralized log management systems (e.g., ELK Stack, Splunk, Graylog) to aggregate and protect logs from tampering or loss.
• Enable real-time alerting and anomaly detection to promptly identify and respond to suspicious activities.
• Ensure logs are comprehensive, consistent, and structured (e.g., JSON format) to facilitate automated analysis and incident investigation.
• Avoid logging sensitive information such as passwords, cryptographic keys, or personal identifiable information (PII) to comply with privacy regulations and reduce risk.

⚡How Strong Software Security Impacts Your Business:

1. Builds Customer Trust and Strengthen Your Brand

Companies with a reputation for secure software win customer trust, boost loyalty, and can often charge premium prices. Security becomes a key brand differentiator.

2. Accelerates Releases with Fewer Security Emergencies

Secure-by-design development minimizes last-minute fixes and vulnerability patching, helping teams ship faster and with more confidence.

3. Reduces Costs from Breaches and Compliance Failures

Proactive security reduces the risk of data breaches, legal liabilities, and non-compliance fines—saving companies millions.

4. Gains a Competitive Edge in B2B Sales

Strong security practices and certifications open doors to enterprise clients and simplify vendor approval processes.

5. Boosts Investor Confidence and Company Valuation

Investors see cybersecurity maturity as a sign of operational excellence and risk mitigation—especially in sensitive sectors.

6. Safeguards Intellectual Property and Source Code

Robust software security protects valuable assets like algorithms, source code, and product roadmaps from theft or leaks.

7. Improves Incident Response and Business Resilience

Security-first organizations detect threats faster and recover more efficiently—minimizing downtime and user disruption.

Let’s break down the 5 foundational security practices every SaaS product should implement:

🔒 Secure Authentication Setup

🛡️ Helps protect your application from common threats such as credential stuffing, brute force attacks, phishing, session hijacking, insecure password storage, account takeover, replay attacks, and privilege escalation.

🚀 Phase 1: MVP (Minimum Viable Product)

✅ Signup/login with password - use Oauth/Firebase or basic JWT/session

✅ Password hashing - Never store raw passwords

✅ Email verification (recommneded) - helps prevent fake accounts

✅ Basic rate limiting - Protects against brute-force login

✅ Frontend auth UI - Clean login/signup/reset forms

✅ Secure session/token handling - Use HttpOnly cookies or secure JWT

⌛ Phase 1 development time: 40-60 hours

💲 Development price: $1000-$1500

• 3rd party authentication provider: Firebase or Oauth - free up to 10,000 monthly active users

📈 Phase 2: Scaling Product (Post-MVP)

✅ MFA (email or authenticator app) - Adds a critical second layer of security against stolen passwords

✅ Session timeout / token refresh - Prevents long-lived sessions from being exploited; improves token hygiene

✅ Centralized logging (via some service provider) - Enables visibility into auth events across environments

✅ Audit logs for auth events - Helps trace suspicious activity, investigate incidents

✅ API rate limiting (per user/IP) - Thwarts brute-force attacks, abuse, and bot activit

✅ Password reset with token expiry - Prevents token reuse and link hijacking; improves account recovery security

✅ Security headers (CSP, HSTS) - Protects against XSS, MITM, and clickjacking in frontend

✅ Regular dependency scans (npm audit, pip-audit) - Prevents supply chain attacks and patches known library vulnerabilities

⌛ Phase 2 development time: 60-100 hours

💲 Development price: $1500 - $2500

🔑 Auth provider (Auth0, Firebase): up to $200/month

👁️ Logging / Monitoring: $30 - $100 / month

👥 Role-based access control (RBAC).

🛡️ By assigning permissions based on clearly defined user roles, RBAC effectively protects against privilege escalation, unauthorized access to sensitive data, and insider threats. It also limits the impact of compromised accounts by containing lateral movement, and helps avoid accidental misuse by restricting actions to what’s necessary for each role.

🎯 Phase 1 (MVP) Goals:

• Hardcoded roles: e.g., Admin, User
• Assign roles manually (via DB or admin interface)
• Protect key routes and UI actions
• No dynamic permission UI or complex hierarchy

Scope of work:

✅ Define RBAC Model - Choose roles, what each role can/cannot do. Document in code or comments.

✅ DB Schema - Add role columns next to the user table or create user_roles table

✅ Authentication Middleware - Backend logic to check user role before sensitive actions (e.g., only Admin can delete users)

✅ Protect UI Elements - Hide or disable frontend buttons/sections based on role (basic conditional rendering)

✅ Manual Role Assignment - Option to manually assign role (via DB admin panel, or hard coded in seed scripts)

✅ Run tests - Basic tests to check role protection (e.g., regular user can’t delete).

⌛ Development time: 16 - 26 hours

💲 Development price: $1500 - $2500

🎯 Phase 2 Goals (Post-MVP):

• Role management is dynamic (not hardcoded)
• Roles are assignable via UI or API
• Permissions are defined per role
• Access is enforced in code and UI
• Support for multi-tenant architecture if needed
• Ready for auditability, compliance, and external integrations

Scope of work:

✅ Model Redesign - Design scalable schema: roles, permissions, user roles, role permissions. Plan for extendability (multi-tenant, soft deletes). Plan for extendability.

✅ DB Migration & Setup - Create/modify DB tables, add indices, relationships. Migrate user roles from MVP.

✅ Backend Enforcement Layer - Enforce permissions

✅ Permission Engine Logic - Add support for permission checks

✅ Role Management API - Create APIs for CRUD on roles, permissions, and user assignments.

✅ Admin UI for RBAC - Admin-facing UI to manage users, assign roles, view access levels (roles + permissions).

✅ Frontend Role Enforcement - Add permission-based access controls to UI (not just role check, but feature-level)

✅ Logging & Audit (Basic) - Log changes to role assignments, sensitive permission changes. Store logs securely.

✅ Testing - Integration + unit tests for access enforcement, edge cases, abuse scenarios.

✅ Documentation - Internal docs for how RBAC works, how to add new roles/permissions.

⏳ Estimated Development Time: 60–90 hours (can stretch toward 120+ hours if you're implementing multi-tenant RBAC)

💲 Development price: $1500 - $2250

💸 Non-Dev Costs (Scaling Phase): depends on the providers and license / subscription type

🔐 + 🌐 Enforce HTTPS/TLS

🛡️ Enforcing HTTPS and TLS encryption across your web application is essential for protecting sensitive data and maintaining user trust. By encrypting all communication between clients and servers, HTTPS/TLS defends against man-in-the-middle (MITM) attacks, session hijacking, and tampering in transit. It also safeguards API interactions, prevents mixed content vulnerabilities, and protects users from phishing by enabling secure, verifiable connections.

🎯 Goals (MVP and scaling product):

• Force all traffic over HTTPS, and serve the app with valid TLS certificates using Let's Encrypt or Cloudflare.
• Harden HTTPS/TLS setup for production-scale use
• Cover multiple environments and services
• Centralize cert management and automate renewals
• Ensure compliance (HSTS, strong ciphers, secure cookies, etc.)
• Load balancing + CDN + edge TLS if applicable

• 🔄 How fast you need to scale
• 📈 Your expected traffic/load
• 🔐 Regulatory/security requirements
• 💵 Budget constraints
• 🛠️ Team skillset and ops maturity
• 🚀 Deployment model (monolith, microservices, serverless, etc.)

Tips for Aligning TLS/HTTPS Architecture with Strategy:

1. Building an MVP? Use managed TLS (Cloudflare Free, Let's Encrypt) for speed and simplicity.
2. Scaling? Plan for automation (renewals, load balancer certs) early.
3. Enterprise target market? Bake in strong TLS configs and secure headers now.
4. Developer-constrained? Offload to services like Cloudflare, Heroku, or Vercel.

🔑 Encrypt Data at Rest and In Transit

🛡️ Implementing strong data encryption both at rest and in transit is essential for safeguarding sensitive information in modern applications. By encrypting data as it travels between clients and servers, you ensure that attackers cannot steal or alter information like passwords, API tokens, or personal user data while it moves across potentially insecure networks.

🎯 Phase 1: Encrypting Data at Rest and In Transit for Your MVP by Leveraging Cloud Infrastructure

The most effective and efficient way to implement data encryption at rest and in transit during the MVP phase is to leverage managed cloud encryption services and infrastructure-level security. This includes enabling HTTPS/TLS encryption for all network communication using trusted providers like Let’s Encrypt or Cloudflare, which automate SSL certificate issuance and renewal with minimal developer effort.

For data at rest encryption, most cloud platforms such as AWS, Azure, and Google Cloud offer built-in encryption options—like encrypted databases (e.g., AWS RDS encryption), encrypted storage volumes, and server-side encrypted object storage (e.g., Amazon S3). Key management can also be securely handled via services like AWS Key Management Service (KMS) or Azure Key Vault, ensuring encryption keys are stored and rotated safely without complex custom development. By offloading encryption responsibilities to the cloud infrastructure, development teams can focus on core product features while ensuring baseline security standards are met quickly and cost-effectively.

⌛ MVP Development time: 9 - 20 hours

💲 Development price: $250 - $500

• Non-development fees: may be charged for key management and load balancer if needed ($15 /month)

🎯 Phase 2: Scaling Encryption Beyond MVP: Combining Infrastructure Security with Application-Level Encryption

To achieve robust security at scale, internal development teams must implement application-level encryption for highly sensitive data such as personally identifiable information and payment details. This involves integrating encryption libraries (e.g., AES-256) directly in the app to encrypt data before storage and securely interacting with key management APIs to fetch and rotate encryption keys.

It also depends on security logging, audit trails, and role-based access control (RBAC) mechanisms, along with incident response workflows tailored to the application environment. This combined approach of leveraging both cloud infrastructure and app-level encryption ensures scalable, resilient, and compliant data protection as your SaaS product matures.

⌛ Phase 2 Development time: 44 - 66 hours

💲 Development price: $1000 - $1700

• Infrastructure Encryption cost: $10 - $40/month (KMS with rotation, IAM policies, audit logging, Monitoring & Alerts on key usage & cert expiry)

☁️ Infrastructure Hardening

🛡️ Helps secure the underlying systems that power your application: servers, networks, containers, and cloud services to reduce vulnerabilities and minimize the risk of cyberattacks.

🎯 Phase 1: Ensure fundamental security without slowing product delivery

Scope of work:

✅ Harden OS images - Configure base server images (e.g., disable unused ports, remove default users)

✅ Set up firewall rules / Security Groups - Enforce least-privilege access between services

✅ Configure IAM roles / policies - Apply least-privilege access control in AWS/GCP

✅ Disable SSH root login / Use key-based auth - Secure remote access

✅ Basic monitoring setup (e.g., CloudWatch) - To detect anomalies

✅ Infrastructure as Code security (e.g., Terraform) - Detect misconfigurations early

⌛ Phase 1 Development time: 25 - 40 hours

💲 Development price: $600 - $1000

🎯 Phase 2 (Scaling) - Advanced Hardening

Scope of work:

✅ Setup Centralized logging (e.g., ELK, Loki, CloudWatch Logs) - Collect & retain logs securely

✅ Intrusion Detection System (IDS) integration - Detect unauthorized activity

✅ Establish Network segmentation / VPC peering / private subnets - stopping attackers from moving around inside your system once they’ve broken in.

✅ Audit trails and compliance logging - Required for SOC2, GDPR, etc

✅ Setup Bastion hosts / VPN access - Secure admin access and monitoring

⌛ Phase 2 Development time: 60 - 100 hours

💲 Development price: $1200 - $2500

🧾 To sum up:

While there are additional security best practices that mature SaaS teams should implement such as secrets management, dependency and code scanning, logging and monitoring, CI/CD security checks, security policy creation, and compliance readiness, the five core software security practices covered above provide the critical foundation.

These areas address the most common vulnerabilities in modern SaaS applications and establish the essential building blocks for a secure, scalable product. By prioritizing authentication, access control, data encryption, HTTPS/TLS enforcement, and infrastructure hardening, your team sets a strong security baseline that future security enhancements can confidently build upon.