Level 22 - Level 23
Overview
This we got an input requesting for a password and a link to the source code.
Source Code Analysis
Let's take a look at the source code. The application is looking out for the URL parameter passwd, if it exists it checks whether it contains the substring iloveyou and also it checks whether the numerical value of passwd is greater than 10. If both of the conditions are statisfied, it shows the credentials for the next level.
The condition $_REQUEST["passwd"] > 10 involves comparing a string to an integer. In PHP, when such a comparison occurs using the greater than (>) operator, PHP attempts to convert the string to a number. If the string begins with a valid numeric value, it undergoes conversion; otherwise, it is treated as 0.
For example, if $_REQUEST["passwd"] is set to "iloveyou123", the string "iloveyou123" will be converted to 0 when compared to 10. Consequently, the condition evaluates as false.
Getting the Password
To satisfy both the condition $_REQUEST["passwd"] > 10 and the additional condition strstr($_REQUEST["passwd"], "iloveyou"), you can create a password that starts with a numeric value greater than 10. For instance, a password like "11iloveyou" meets these conditions. When comparing this password to 10, PHP converts it to the numeric value 11. As a result, the condition $_REQUEST["passwd"] > 10 evaluates to true. Additionally, the password contains the substring "iloveyou," fulfilling the requirements for both conditions and granting access to the credentials for the next level.
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