I would like to make your attention on bug which was introduced tonight and can affect some people who are using (var)char field to store timestamp data. It is not worst security bug. It affects only people who already had bug in their code. Just now this bug become visible/exploitable. This is not MySQL bug. This is how people use their database. Also similar situation can be found in other software. I would like to inform people in public list as maybe some people have to search similar problems. The problem: Computers store time and date usually as integer value representing amount of seconds from 1 January 1970. Tonight it overrolled from 999999999 to 1000000000. Possible bug and exploit relies on fact that some people have used character type of field to store this seconds information (we have already such case) example: mysql> create table session (expire varchar(100) not null); Query OK, 0 rows affected (0.31 sec) mysql> insert into session values (999999997), (999999998), (999999999), (1000000000), (1000000001); Query OK, 5 rows affected (0.00 sec) Records: 5 Duplicates: 0 Warnings: 0 mysql> mysql> select * from session; +------------+ | expire | +------------+ | 999999997 | | 999999998 | | 999999999 | | 1000000000 | | 1000000001 | +------------+ 5 rows in set (0.00 sec) mysql> Let's assume that this table contains values we use somewhere to authenticate users. After user logs in, we write down session expiry time and later we check it like this: mysql> select count(*) from session where expire >= '1000032535'; +----------+ | count(*) | +----------+ | 3 | +----------+ 1 row in set (0.00 sec) mysql> WOW, what happened? Shouldn't be 100003253 bigger than any value in table? It worked yesterday! In MySQL we suggested people to use quotation marks around integer values. This can avoid many web-based attacks targeted to modify SQL commands (more information on http://www.mysql.com/doc/G/e/General_security.html). This is the reason why people put quotation marks around integer expressions and this is correct. Also automatic type casting will fix the source problem is column data is integer or some time/date vale. But when both column is character type and expression, they get compared as strings. And as we know, strings get sorted in order: 1,11,2,22 but integers: 1.2.11.22 So, this is why 100003253 < 1000000000 It is possible that some web applicatons have endless expiry times now and not only in MySQL contexts. -- For technical support contracts, goto https://order.mysql.com/ __ ___ ___ ____ __ / |/ /_ __/ __/ __ \/ / Mr. Tonu Samuel <tonu@mysql.com> / /|_/ / // /\ \/ /_/ / /__ MySQL AB, Security Administrator /_/ /_/\_, /___/\___\_\___/ Hong Kong, China <___/ www.mysql.com
