Group items tagged

length must be at least 128 bits (16 bytes)

Session ID Length

Session ID Name Fingerprinting

Session ID Properties

Session ID Entropy

must be unpredictable (random enough) to prevent guessing attacks

good PRNG (Pseudo Random Number Generator) must be used

must provide at least 64 bits of entropy

Session ID Content (or Value)

content (or value) must be meaningless

identifier on the client side

meaning and business or application logic associated to the session ID must be stored on the server side

session objects or in a session management database or repository

create cryptographically strong session IDs through the usage of cryptographic hash functions such as SHA1 (160 bits).

Session Management Implementation

defines the exchange mechanism that will be used between the user and the web application to share and continuously exchange the session ID

token expiration date and time

This is one of the reasons why cookies (RFCs 2109 & 2965 & 6265 [1]) are one of the most extensively used session ID exchange mechanisms, offering advanced capabilities not available in other methods

Transport Layer Security

use an encrypted HTTPS (SSL/TLS) connection for the entire web session

process where the user credentials are exchanged.

“Secure” cookie attribute

must be used to ensure the session ID is only exchanged through an encrypted channel

never switch a given session from HTTP to HTTPS, or viceversa

should not mix encrypted and unencrypted contents (HTML pages, images, CSS, Javascript files, etc) on the same host (or even domain - see the “domain” cookie attribute)

should not offer public unencrypted contents and private encrypted contents from the same host

www.example.com over HTTP (unencrypted) for the public contents

secure.example.com over HTTPS (encrypted) for the private and sensitive contents (where sessions exist)

only has port TCP/80 open

only has port TCP/443 open

“HTTP Strict Transport Security (HSTS)” (previously called STS) to enforce HTTPS connections.

Secure Attribute

instructs web browsers to only send the cookie through an encrypted HTTPS (SSL/TLS) connection

HttpOnly Attribute

instructs web browsers not to allow scripts (e.g. JavaScript or VBscript) an ability to access the cookies via the DOM document.cookie object

Domain and Path Attributes

instructs web browsers to only send the cookie to the specified domain and all subdomains

instructs web browsers to only send the cookie to the specified directory or subdirectories (or paths or resources) within the web application

vulnerabilities in www.example.com might allow an attacker to get access to the session IDs from secure.example.com

Expire and Max-Age Attributes

it will be considered a

and will be stored on disk by the web browser based until the expiration time

use non-persistent cookies for session management purposes, so that the session ID does not remain on the web client cache for long periods of time, from where an attacker can obtain it.

Session ID Life Cycle