![]() ![]() This series of payloads modifies the original query to order the results by different columns in the result set. For example, assuming the injection point is a quoted string within the WHERE clause of the original query, you would submit: The first method involves injecting a series of ORDER BY clauses and incrementing the specified column index until an error occurs. When performing a SQL injection UNION attack, there are two effective methods to determine how many columns are being returned from the original query. ![]() ![]() Which columns returned from the original query are of a suitable data type to hold the results from the injected query?ĭetermining the number of columns required in a SQL injection UNION attack How many columns are being returned from the original query? To carry out a SQL injection UNION attack, you need to ensure that your attack meets these two requirements. The data types in each column must be compatible between the individual queries. The individual queries must return the same number of columns. This SQL query will return a single result set with two columns, containing values from columns a and b in table1 and columns c and d in table2.įor a UNION query to work, two key requirements must be met: SELECT a, b FROM table1 UNION SELECT c, d FROM table2 The UNION keyword lets you execute one or more additional SELECT queries and append the results to the original query. This results in a SQL injection UNION attack. Offset specify the number of records to skip before starting to return the records db.Limit( 3).Find(&users)ĭb.Limit( 10).Find(&users1).Limit( -1).When an application is vulnerable to SQL injection and the results of the query are returned within the application's responses, the UNION keyword can be used to retrieve data from other tables within the database. Limit specify the max number of records to retrieve SELECT * FROM users ORDER BY FIELD(id,1,2,3) When the destination object has a primary value, the primary key will be used to build the condition, for example: var user = User, If the primary key is a string (for example, like a uuid), the query will be written as follows: db.First(&user, "id = ?", "1b74413f-f3b8-409f-ac47-e8c062e3472a") SELECT * FROM users WHERE id IN (1,2,3) When working with strings, extra care needs to be taken to avoid SQL Injection check out Security section for details. Objects can be retrieved using primary key by using Inline Conditions if the primary key is a number. SELECT * FROM `languages` ORDER BY `languages`.`code` LIMIT 1 no primary key defined, results will be ordered by first field (i.e., `Code`) works because model is specified using `db.Model()` SELECT * FROM `users` ORDER BY `users`.`id` LIMIT 1 works because destination struct is passed in Additionally, if no primary key is defined for relevant model, then the model will be ordered by the first field. They only work when a pointer to the destination struct is passed to the methods as argument or when the model is specified using db.Model(). The First and Last methods will find the first and last record (respectively) as ordered by primary key. Using Find without a limit for single object db.Find(&user) will query the full table and return only the first object which is not performant and nondeterministic If you want to avoid the ErrRecordNotFound error, you could use Find like db.Limit(1).Find(&user), the Find method accepts both struct and slice data Result.RowsAffected // returns count of records foundĮrrors.Is(result.Error, gorm.ErrRecordNotFound) SELECT * FROM users ORDER BY id DESC LIMIT 1 Get last record, ordered by primary key desc SELECT * FROM users ORDER BY id LIMIT 1 Get the first record ordered by primary key GORM provides First, Take, Last methods to retrieve a single object from the database, it adds LIMIT 1 condition when querying the database, and it will return the error ErrRecordNotFound if no record is found. ![]()
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