mysql - How to handle these 404 errors that look like... - Server Fault
While these lines in your question seems to only SELECT information from the database and wouldn't per se cause any direct harm, the purpose can be collecting information of vulnerable sites before the actual strike.
The SQL Injection Knowledge Base
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SQL Инъекции | Page 10 | ANTICHAT - Security online community
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MySQL :: MySQL 8.0 Reference Manual :: 12.10 Cast Functions and...
Produces a string with the VARCHAR data type, unless the expression expr is empty (zero length), in which case the result type is CHAR(0) . If the optional length N is given, CHAR(N) causes the cast to use no more than N characters of the argument.
MySQL injection - HackTricks
UniOn Select 1,2,3,4,...,gRoUp_cOncaT(0x7c,schema_name,0x7c)+fRoM+information_schema.schemata.
Шпаргалка по SQL инъекциям | DefconRU
7. Строки без кавычек Есть несколько способов не использовать кавычки в запросе, например с помощью CHAR() (MS) и CONCAT() (M). Синтаксис: SELECT 0x457578 (M).
SQL Injection Bypassing WAF | OWASP Foundation
SQL Injection into a Numeric parameter Example: SELECT * from table where id = 123. Exploitation of SQL Injection vulnerabilities is divided into classes according to the DBMS type and injection conditions.
Exploiting hard filtered SQL Injections | Reiners' Weblog
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?id=1 and 1=0 union select null,column_name,null from information_schema.columns where table_name='foundtablename' LIMIT 0,1-- -. After you have found interesting tables and its column names you can start to extract data.
Injection in Insert, Update and Delete Statements | Blog of Osanda
Introduction Most of the time when we talk about SQL injection we extract data by using the union keyword, error based, blind boolean and time based injection methods. All this come under a place where the application is performing a select statement on the back-end database.