Validating data input
Data from all potentially untrusted sources should be subject to input validation, including not only Internet-facing web clients but also backend feeds over extranets, from suppliers, partners, vendors or regulators, each of which may be compromised on their own and start sending malformed data.
Syntactic validation should enforce correct syntax of structured fields (e.g.
You don't need to worry about whatever the Data box shows, as that's disabled with the Custom option.
Note: You must enter the data validation formula for cell A2 first, then copy A2 to A3: A10 so that the second argument to the COUNTIF will match the current cell.
To ensure that the application is robust against all forms of input data, whether obtained from the user, infrastructure, external entities or database systems. This weakness leads to almost all of the major vulnerabilities in applications, such as Interpreter Injection, locale/Unicode attacks, file system attacks and buffer overflows.
All sections should be reviewed The most common web application security weakness is the failure to properly validate input from the client or environment.