OWASP Top Ten Cheat Sheet

Introduction

The following is a developer-centric defensive cheat sheet for the OWASP Top Ten Project. It also presents a quick reference based on OWASP Testing Project to help how to identify the risks.

OWASP Top Ten Cheat Sheet

	Presentation	Controller	Model	Testing (OWASP Testing Guide V3)
A1 Injection	Render: Set a correct content type Set safe character set (UTF-8) Set correct locale On Submit: Enforce input field type and lengths Validate fields and provide feedback Ensure option selects and radio contain only sent values	Canonicalize using correct character set Positive input validation using correct character set (NR) Negative input validation. (LR) Sanitize input. Tip: updating a negative list (such as looking for "script", "sCrIpT", "ßCrîpt", etc) will require expensive and constant deployments and will always fail as attackers work out your list of "bad" words. Positive validation is simpler, faster and usually more secure and needs updating far less than any other validation mechanism.	Parameterized queries Object relational model (Hibernate). Active Record design pattern. Stored procedures. Escape mechanisms such as ESAPI's Encoder, EncodeForLDAP() or Encoder.EncodeforOS() Tip: All SQL Injection is due to dynamic SQL queries. Strongly consider prohibiting dynamic SQL queries within your organization	4.8.5 SQL Injection (OWASP-DV-005) 4.8.6 LDAP Injection (OWASP-DV-006) 4.8.7 ORM Injection (OWASP-DV-007) 4.8.8 XML Injection (OWASP-DV-008) 4.8.9 SSI Injection (OWASP-DV-009) 4.8.10 XPath Injection (OWASP-DV-010) 4.8.11 IMAP/SMTP Injection (OWASP-DV-011) 4.8.12 Code Injection (OWASP-DV-012) 4.8.13 OS Commanding (OWASP-DV-013) 4.8.14 Buffer overflow (OWASP-DV-014)
A2 XSS	Render Set correct content type Set safe character set (UTF-8) Set correct locale Output encode all user data as per output context Set input constraints On Submit Enforce input field type and lengths Validate fields and provide feedback Ensure option selects and radio contain only sent values	Canonicalize using correct character set Positive input validation using correct character set (NR) Negative input validation (LR) Sanitize input Tip: Only process data that is 100% trustworthy. Everything else is hostile and should be rejected.	Tip: Do not store data HTML encoded in the database. This prevents new uses for the data, such as web services, RSS feeds, FTP batches, data warehousing, cloud computing, and so on. Tip: Use OWASP Scrubbr to clean tainted or hostile data from legacy data	4.8.1 Testing for Reflected Cross Site Scripting (OWASP-DV-001) 4.8.2 Testing for Stored Cross Site Scripting (OWASP-DV-002) 4.8.3 Testing for DOM based Cross Site Scripting (OWASP-DV-003) 4.8.4 Testing for Cross Site Flashing (OWASP-DV004)
A3 Weak authentication and session management	Render Validate user is authenticated Validate role is sufficient for this view Set "secure" and "HttpOnly" flags for session cookies Send CSRF token with forms	Design Only use inbuilt session management Store secondary SSO / framework / custom session identifiers in native session object – do not send as additional headers or cookies Validate user is authenticated Validate role is sufficient to perform this action Validate CSRF token	Validate role is sufficient to create, read, update, or delete data Tip: Consider the use of a "governor" to regulate the maximum number of requests per second / minute / hour that this user may perform. For example, a typical banking user should not perform more than ten transactions a minute, and one hundred per second is dangerous and should be blocked.	4.4.2 Testing for user enumeration (OWASP-AT-002) 4.4.3 Testing for Guessable (Dictionary) User Account (OWASP-AT-003) 4.4.4 Brute Force Testing (OWASP-AT-004) 4.4.6 Testing for vulnerable remember password and pwd reset (OWASP-AT-006) 4.4.5 Testing for bypassing authentication schema (OWASP-AT-005) 4.4.7 Testing for Logout and Browser Cache Management (OWASP-AT-007) 4.4.8 Testing for CAPTCHA (OWASP-AT-008) 4.4.9 Testing Multiple Factors Authentication (OWASP-AT-009) 4.4.10 Testing for Race Conditions (OWASP-AT-010) 4.5.1 Testing for Session Management Schema (OWASP-SM-001) 4.5.2 Testing for Cookies attributes (OWASP-SM-002) 4.5.3 Testing for Session Fixation (OWASP-SM_003) 4.5.4 Testing for Exposed Session Variables (OWASP-SM-004) 4.5.5 Testing for CSRF (OWASP-SM-005) 4.6.2 Testing for bypassing authorization schema (OWASP-AZ-002) 4.6.3 Testing for Privilege Escalation (OWASP-AZ-003)
A4 Insecure Direct Object Reference	If data is from internal trusted sources, no data is sent Or Render Send indirect random access reference map value	Obtain data from internal, trusted sources Or Obtain direct value from random access reference access map	Validate role is sufficient to create, read, update, or delete data	4.6.1 Testing for Path Traversal (OWASP-AZ-001)
A5 Cross Site Request Forgery	Pre-render Validate user is authenticated Validate role is sufficient for this view Render Send CSRF token Set "secure" and "HttpOnly" flags for session cookies	Validate CSRF token Validate role is sufficient to perform this action Validate role is sufficient Tip: CSRF is always possible if there is XSS, so make sure XSS is eliminated within your application.	Validate role is sufficient to create, read, update, or delete data	4.5.5 Testing for CSRF (OWASP-SM-005)
A6 Security Misconfiguration	Ensure web servers and application servers are hardened PHP – Ensure allow_url_fopen and allow_url_include are both disabled in php.ini. Consider the use of Suhosin extension	Ensure web servers and application servers are hardened XML – Ensure common web attacks (remote XSLT transforms, hostile XPath queries, recursive DTDs, and so on) are protected by your XML stack. Do not hand craft XML documents or queries – use the XML layer.	Ensure database servers are hardened	4.2.6 Analysis of Error Codes (OWASP-IG-006) 4.3.2 DB Listener Testing (OWASP-CM-002) 4.3.3 Infrastructure Configuration Management Testing (OWASP-CM-003) 4.3.4 Application Configuration Management Testing (OWASP-CM-004) 4.3.5 Testing for File Extensions Handling (OWASP-CM-005) 4.3.6 Old, Backup and Unreferenced Files (OWASP-CM-006) 4.3.7 Infrastructure and Application Admin Interfaces (OWASP-CM-007) 4.3.8 Testing for HTTP Methods and XST (OWASP-CM-008)
A7 Insufficient Cryptographic Storage	Design Use strong ciphers (AES 128 or better) Use strong hashes (SHA 256 or better) with salts for passwords Protect keys more than any other asset Render Do not send keys or hashes to the browser	Design Use strong ciphers (AES 128 or better) Use strong hashes (SHA 256 or better) with salts for passwords Protect keys more than any other asset Tip: Only certain personally identifiable information and sensitive values MUST be encrypted. Encrypt data that would be embarrassing or costly if it was leaked or stolen. Tip: It is best to encrypt data on the application server, rather than the database server.	Design Tip: Do not use RDBMS database, row or table level encryption. The data can be retrieved in the clear by anyone with direct access to the server, or over the network using the application credentials. It might even traverse the network in the clear despite being "encrypted" on disk.
A8 Failure to Restrict URL access	Design Ensure all non-web data is outside the web root (logs, configuration, etc) Use octet byte streaming instead of providing access to real files such as PDFs or CSVs or similar Ensure every page requires a role, even if it is "guest" Pre-render Validate user is authenticated Validate role is sufficient to view secured URL Render Send CSRF token	Validate user is authenticated Validate role is sufficient to perform secured action Validate CSRF token Tip: It's impossible to control access to secured resources that the web application server does not directly serve. Therefore, PDF reports or similar should be served by the web application server using binary octet streaming. Tip: Assume attackers will learn where "hidden" directories and "random" filenames are, so do not store these files in the web root, even if they are not directly linked.	Validate role is sufficient to create, read, update, or delete data	4.4.5 Testing for bypassing authentication schema (OWASP-AT-005) 4.6.1 Testing for Path Traversal (OWASP-AZ-001) 4.6.2 Testing for bypassing authorization schema (OWASP-AZ-002)
A9 Insufficient Transport Layer Protection	Use TLS 1.2 or later for all web communications Buy extended validation (EV) certificates for public web servers Tip: Use TLS 1.2 always – even internally. Most snooping is done within corporate networks – and it is as easy and unethical as fishing with dynamite.	Mandate strong encrypted communications between web and database servers and any other servers or administrative users	Mandate strong encrypted communications with application servers and any other servers or administrative users	4.3.1 SSL/TLS Testing (OWASP-CM-001) 4.4.1 Credentials transport over an encrypted channel (OWASP-AT-001)
A10 Unvalidated Redirects and Forwards	Design the app without URL redirection parameters or Render Use random indirect object references for redirection parameters	Design the app without URL redirection parameters or Obtain direct redirection parameter from random indirect reference access map (LR) Positive validation of redirection parameter (NR) Java – Do not forward() requests as this prevents SSO access control mechanisms	Validate role is sufficient to create, read, update, or delete data

Authors and Primary Editors

Andrew van der Stock vanderaj[at]owasp.org

Ismael Rocha Gonçalves ismaelrg[at]gmail.com

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