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Broken authentication and session management

Broken authentication and session management. Daneliuc Ana-Maria, MISS2. 2nd Place in OWASP Top 10 2013 Application Vulnerabilities. vast threat, strongly related to other top 10 vulnerabilities (XSS, Sensitive Data Exposure, CSRF etc.)

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Broken authentication and session management

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  1. Broken authentication and session management Daneliuc Ana-Maria, MISS2

  2. 2nd Place in OWASP Top 10 2013 Application Vulnerabilities • vast threat, strongly related to other top 10 vulnerabilities (XSS, Sensitive Data Exposure, CSRF etc.) • includes all aspects of handling user authentication and managing active sessions • unfortunately, not all of these aspects have a standard implementation

  3. Authentication • the process of verifying a user’s identity • commonly performed by submitting a username/user id and more private items that only a given user should know • data is usually persisted in a database

  4. Password guessing attacks • brute force • dictionary attacks

  5. Password guessing attacks • lookup tables (precomputed) – see the CrackStation database • rainbow tables (precomputed) • reverse lookup tables (computed during the attack)

  6. Authentication - Common use cases, attacks and guidelines • Brute force or dictionary attacks • Enforce proper password strength: • Password must meet at least 3 out of the following 4 complexity rules • at least 1 uppercase character (A-Z) • at least 1 lowercase character (a-z) • at least 1 digit (0-9) • at least 1 special character(punctuation) • at least 10 characters • at most 128 characters • not more than 2 identical characters in a row (e.g., 111 not allowed) • the password should not contain parts of the username or targeted application

  7. Authentication - Common use cases, attacks and guidelines • Brute force or dictionary attacks • Lock account after repeated authentication failures and implement a reset password mechanism • Show generic error messages: Incorrect Response Examples • "Login for User foo: invalid password" • "Login failed, invalid user ID" • "Login failed; account disabled" • "Login failed; this user is not active" Correct Response Example • "Login failed; Invalid userID or password”

  8. Authentication - Common use cases, attacks and guidelines • Brute force or dictionary attacks • Use Multi-Factor Authentication • besides the password, another information is needed, sent via an “out-of-band” channel: • email token • hardware tokens • SMS token • Facebook and Yahoo request this when there is a login attempt from an unknown location

  9. Authentication - Common use cases, attacks and guidelines • Passwords database gets compromised => lookup tables & co. • Developers - NEVER store the passwords in clear • use a strong cryptographic hash function (SHA512, SHA-3, WHIRLPOOL etc) to hash them • add salt: hash(password + “cxafZoufdsX”); makes precomputed hash tables useless • do not reuse the salt • always hash on the server side; do not rely only on client side hashing • Users – do not use the same password on multiple websites

  10. Authentication - Common use cases, attacks and guidelines • Man-in-the-middle attacks on the network • Sniffing – intercepting packets over the network • Spoofing – a malicious entity pretending to be an innocent one, by falsifying data

  11. Authentication - Common use cases, attacks and guidelines • Man-in-the-middle attacks on the network (sniffing & spoofing) • All sensitive operations should be enforced under HTTPS • encryption to prevent sniffing – SSL/TLS • authenticationto prevent spoofing – use of Public Key Encryption with certificates issued by a Trusted Authority (e.g. VeriSign, Thwate, etc)

  12. Authentication - Common use cases, attacks and guidelines • Man-in-the-middle attacks on the network (sniffing & spoofing) • Do Not Provide Non-HTTPS Pages for Secure Content • The <form> html action can easily be spoofed to another URL by an attacker who sniffs the html code as it is downloaded from the server • Even worse, the attacker can insert javascript code that steals credentials as you type them

  13. Authentication - Common use cases, attacks and guidelines • Man-in-the-middle attacks on the network (sniffing & spoofing) • Do not mix encrypted and unencrypted contents (HTML pages, images, CSS, Javascript files, etc) on the same host • the request of any web object over an unencrypted channel might disclose the session ID • Use HTTPS for all authenticated pages • failure to utilize TLS for authenticated pages after the login enables an attacker to view the unencrypted session ID (“Set-Cookie: sid=af45e543” header)

  14. Authentication - Common use cases, attacks and guidelines • URL attacks • Do not include sensitive data in the URL, even when using HTTPS • the URL may leak in the referrer header at the destination server • the entire URL is cached in the browser history. This may expose sensitive data to any other user of the workstation. • CSRF (Cross-Site Request Forgery) attacks • Require Re-authentication for Sensitive Features (e.g. buying, updating the credit card number) • in case the attacker is aware of the user being authenticated, it can send or inject a link to perform actions on behalf of the user

  15. Authentication – Use of authentication protocols that require no password • OAuth & OpenID– Facebook, Google, Twitter APIs • Suitable in cases of mobile clients, that can store credentials in a way that the server cannot control

  16. Session Management • A web session is a sequence of network HTTP request and response transactions associated to the same user and managed by the server • The session ID or token binds the user authentication credentials (in the form of a user session) to the user HTTP traffic and the appropriate access controls enforced by the web application

  17. Rules for a good session id Do not use session id name fingerprinting : PHPSESSID , JSESSIONID Use a long enough session id to prevent brute force attacks (at least 16 bytes) Have session id entropy – make the session id unpredictable (E.g. not related to the username in any way)

  18. Session Management – ways to store the session id • Not recommended: • in the URL: https://example.com?SID=dsadas4738 • hidden form fields: <form><input type=“hidden” name=“sid” value=“s8s1sag”/></form> • Recommended: • in cookies having: • “Secure” Attribute, that instructs web browsers to only send the cookie through an encrypted HTTPS (SSL/TLS) connection • “HttpOnly” Attribute, that instructs web browsers not to allow scripts (e.g. JavaScript) the ability to access the cookies via the DOM document.cookie object. • Expire or Max-Age Attributes – prevents long time caching

  19. Session Management – common use cases, attacks and guidelines • Session fixation •  the attacker sets a user's session id to one known to him; it only has to wait for the user to log in • sending a malicious link with the session injected in the URL • XSS by setting the cookie session id: document.cookie=”sessionid=1234”; • Solutions: • Do not accept session identifiers from GET / POST variables: <a href=http://vulnerable.com?SID=MY_KNOWN_SID>Check this out</a> • After successful login, change the session id • Properly invalidate the session id after logout • Use HttpOnly on session cookies

  20. Session Management – common use cases, attacks and guidelines • Session sidejacking • the attacker uses packet sniffing to read network traffic between two parties to steal the session cookie or to read the “Set-Cookie” header after login, proceeding with session fixation afterwards • the cookie session id has a predictable generation algorithm and we can guess a session id and bypass authentication • Solutions: • Only use HTTPS for authentication and session cookies with “Secure” attribute • Use a strong random generator for the session id • Do not accept the header “Cookie: sid=adf45632” from any other user agent other than a browser

  21. Resources Most OWASP resources: https://www.owasp.org/index.php/Authentication_Cheat_Sheet https://www.owasp.org/index.php/Session_Management_Cheat_Sheet https://www.owasp.org/index.php/Session_fixation https://www.owasp.org/index.php/Transport_Layer_Protection_Cheat_Sheet https://www.owasp.org/index.php/Top_10_2013-A2-Broken_Authentication_and_Session_Management - lists other important tools also https://www.owasp.org/index.php/Category:OWASP_WebGoat_Project – WebGoat Project, available in most programming languages https://crackstation.net/hashing-security.htm - About correct password hashing ESAPI Authenticator and User APIs – An Authentication API made by the OWASP community

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