Database Security

Database Security

John Ortiz

Lecture 23 Database Security 2

Secure Passwords Two main requirements for choosing a

secure password: 1) MUST be easy to remember 2) MUST be difficult to guess

Do NOT pick any of these types of passwords because they are easily guessed! your name, spouse’s name, child’s name,

pet’s name, friend’s name, fantasy character’s name, coworker’s name, ANYONE’S NAME


Secure Passwords (cont) name of operating system or host

computer your license plate, SSAN, phone number birth date, anniversary date, any

significant date information easily obtainable about you any word out of any dictionary a single word (in any foreign language) a place slang or profanity


Secure Passwords (cont) Do NOT use any of these either!

Groupings of similar letters patterns of letters on a keyboard such as

‘asdfgh’ or ‘qwerty’ any of the previous spelled backwards any of the above followed or preceded by

a single digit


Secure Passwords substituting similar numbers for letters:

0 for O, 3 for e, etc.

substituting similar characters for letters: @ for a, ! for I

adding numbers to anything crackable tarot12, car9rot

using obscure words like ‘quamash’


Secure Passwords (cont) NEVER write down any secure password,

since it will then no longer be secure What is left?

Should be at least 8 characters, with one or more special characters (such as !, @, #, etc.), and one or more digits

first letter from each word in a line out of a favorite book or song Example: Off We Go in 2 the Wild Blue

Yonder (owg2wby)


Secure Passwords (cont) groupings of unrelated words Remember, a UNIX system only uses the

first 8 characters to develop the encrypted password file!

Do NOT use any examples from here Examples of CRACKED PASSWORDS

L0v3rs, br0nc0s, kaitlyn1 Qwerty1, hoquiam5, nitwit1


Security Mechanisms Discretionary Security – grant privileges to

users, including access to specific files, records, attributes, etc. May have r, w, x, d specified separately

Mandatory Security – used to enforce multi-level security systems. Data is divided into classifications such that a user only has access to data at his/her classification or lower


Discretionary Mechanisms Authorization Identifier – refers to a user

account or group of accounts (login, password)

Two levels of privileges: Account level – privileges each account

holds independent of relations in DB Relation level – control access to

individual relations or views SQL uses GRANT/REVOKE to assign

privileges


GRANT Privileges SQL allows the granting of the following

types of privileges: SELECT (retrieval) MODIFY (update, delete, insert) REFRENCE (reference specific relations

when specifying integrity constraints) Views allow very specific control over which

attributes are visible to a particular user Privileges can propagate from one user to

another


REVOKE Privileges SQL allows the suspension of previously

granted privileges If a privilege has propagated, and the owner

account revokes it, all the propagated privileges will also be revoked Remember, this is not exactly how Oracle

implements this feature If an account receives privileges from 2 or

more sources, then the privileges are only revoked if all sources revoke them


Mandatory Access Control Security Classes:

Top Secret – revelation may cause catastrophic damage to U.S. security

Secret – revelation may cause grave damage to U.S. security

Confidential – revelation may cause damage to U.S. security

Unclassified – read it in the newspaper


Mandatory Access Control (cont) May read any data up to your level of

classification May write to any data at or above your

classification (can NOT write to lower classification because it may contain higher level information)

In a relational database, attributes are given a classification level

In addition, the tuple itself is classified at the highest level of any of its attributes


Mandatory Access Control (cont) An apparent key is the set of attributes that

would have formed the PK in a regular DB A multilevel relation will appear different to

different users – some parts of the PK may be classified at a higher level

In some cases, tuples stored at a higher level can be downgraded and viewed at a lower level

In other cases, 2 sets of tuples may need to be stored

Interesting possibilities for Norm., CC & R, Consistency, etc. - EVERYTHING IS HARDER!


Multilevel Security Entity Integrity – all attributes that are

members of the apparent key must not be null and must have same security classification within each tuple All other attributes must have

classification greater than or equal to apparent key


Statistical Database Security Protect access to individual data items, but

not the aggregate results Possible to infer individual data from some

statistical queries (I.e. if the query limits the number of tuples to just a few)

Solutions: Restrict queries that only access a few tuples Restrict repeated access to same data set

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Database Security