Remove redundant section in privilege escalation document (#1157)

document/4-Web_Application_Security_Testing/05-Authorization_Testing/03-Testing_for_Privilege_Escalation.md

@@ -184,10 +184,6 @@ For example:
 startswith(), endswith(), contains(), indexOf()
 ```
 
-### Weak SessionID
-
-Weak Session ID has algorithm may be vulnerable to brute force attack. For example, one site is using `MD5(Password + UserID)` as sessionID. Then, testers may guess or generate the sessionID for other users.
-
 ## References
 
 ### Whitepapers