Session Management Cheat Sheet - OWASP - 0 views
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Session Management Cheat Sheet
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should not be extremely descriptive nor offer unnecessary details
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change the default session ID name of the web development framework to a generic name
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length must be at least 128 bits (16 bytes)
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Session ID Length
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Session ID Name Fingerprinting
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Session ID Properties
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Session ID Entropy
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must be unpredictable (random enough) to prevent guessing attacks
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good PRNG (Pseudo Random Number Generator) must be used
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must provide at least 64 bits of entropy
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Session ID Content (or Value)
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content (or value) must be meaningless
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identifier on the client side
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meaning and business or application logic associated to the session ID must be stored on the server side
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session objects or in a session management database or repository
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create cryptographically strong session IDs through the usage of cryptographic hash functions such as SHA1 (160 bits).
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Session Management Implementation
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defines the exchange mechanism that will be used between the user and the web application to share and continuously exchange the session ID
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token expiration date and time
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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
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Transport Layer Security
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use an encrypted HTTPS (SSL/TLS) connection for the entire web session
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not only for the authentication
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process where the user credentials are exchanged.
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“Secure” cookie attribute
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must be used to ensure the session ID is only exchanged through an encrypted channel
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never switch a given session from HTTP to HTTPS, or viceversa
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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)
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should not offer public unencrypted contents and private encrypted contents from the same host
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www.example.com over HTTP (unencrypted) for the public contents
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secure.example.com over HTTPS (encrypted) for the private and sensitive contents (where sessions exist)
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only has port TCP/80 open
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only has port TCP/443 open
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“HTTP Strict Transport Security (HSTS)” (previously called STS) to enforce HTTPS connections.
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Secure Attribute
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instructs web browsers to only send the cookie through an encrypted HTTPS (SSL/TLS) connection
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HttpOnly Attribute
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instructs web browsers not to allow scripts (e.g. JavaScript or VBscript) an ability to access the cookies via the DOM document.cookie object
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Domain and Path Attributes
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instructs web browsers to only send the cookie to the specified domain and all subdomains
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“Domain” cookie attribute
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“Path” cookie attribute
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instructs web browsers to only send the cookie to the specified directory or subdirectories (or paths or resources) within the web application
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vulnerabilities in www.example.com might allow an attacker to get access to the session IDs from secure.example.com
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Expire and Max-Age Attributes
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“Max-Age”
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“Expires” attributes
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it will be considered a
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persistent cookie
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and will be stored on disk by the web browser based until the expiration time
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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.
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Session ID Life Cycle