I get a lot of logs saying someone is trying to reach
/sign_in?t=login'+union+select+char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33),char(38,126,33)+--+
now, /sign_in?t=login is a valid url. the rest is the sqli attempt..
What are they trying to do?
char(38,126,33)you will find many more attempts. I think in itself this attempt is harmless, it is only used to test whether a SQL injection is possible. Only if it is, more exploit attempts will follow. – Jeff Aug 24 '14 at 08:20&~!without using quotes. The SQL select three innocent but uncommon characters from the database. The exploiter will watch if those three characters end up in the resulting HTML page and know there is a vulnerability. – Jeff Aug 24 '14 at 08:28