Clarify IdP-initiated SSO section: specify login CSRF, remove MITM reference #1876

Author: 0xgaurav

cheatsheets/SAML_Security_Cheat_Sheet.md

@@ -93,7 +93,12 @@ Need an architectural diagram? The [SAML technical overview](https://www.oasis-o
 
 ## Unsolicited Response (ie. IdP Initiated SSO) Considerations for Service Providers
 
-Unsolicited Response is inherently [less secure](https://www.identityserver.com/articles/the-dangers-of-saml-idp-initiated-sso) by design due to the lack of [CSRF](https://owasp.org/www-community/attacks/csrf) protection. However, it is supported by many due to the backwards compatibility feature of SAML 1.1. The general security recommendation is to not support this type of authentication, but if it must be enabled, the following steps (in addition to everything mentioned above) should help you secure this flow:
+Unsolicited Response is inherently less secure by design due to the lack of **login [CSRF](https://owasp.org/www-community/attacks/csrf)** protection. This limitation arises because the Service Provider (SP) has no opportunity to create a pre-login session or verify that the authentication request was intentionally initiated by the user.  
+
+While this design does not make IdP-initiated SSO uniquely vulnerable to Man-in-the-Middle (MITM) attacks—those risks apply equally to SP-initiated flows if transport security is compromised—it does remove an important layer of login intent validation.  
+
+Despite these concerns, IdP-initiated SSO remains supported for backward compatibility (notably with SAML 1.1). If it must be enabled, the following steps (in addition to those mentioned above) should help secure this flow:
+
 
 - Follow the validation process mentioned in [SAML Profiles (section 4.1.5)](https://docs.oasis-open.org/security/saml/v2.0/saml-profiles-2.0-os.pdf). This step will help counter the following attacks:
     - Replay (6.1.2)