This article will give information regarding the behaviour of junos:FACEBOOK-ACCESS, junos:FACEBOOK-MESSENGER application signatures and there effects on the multimedia file download on Facebook Messenger application.

The user will not be able to download any multimedia files shared over Facebook Messenger application if junos:FACEBOOK-ACCESS signature is not allowed in the security policy.

It is as per expected behaviour and design. The junos:FACEBOOK-MESSENGER application classifies Audio flows, Video flows, as well as Text Chat-related flows. Whenever user does a photo or file transfer, the app is classified as junos:FACEBOOK-ACCESS and if it has been denied in the policy configuration, the multimedia file will not load on the Facebook Messenger application. 

Debug:-

[1480] T01 dynapp_policy_search: Hit policy_id 4 with action 2.

[1504] T01 dynapp_get_app_name_and_id: match_state(4), ext_match_state(2), appid(199), ext_appid(244), ssl_enabled(Yes), appname(SSL), ext_appname (FACEBOOK-ACCESS)

root@vSRX_AppID> show services application-identification application detail junos:FACEBOOK-MESSENGER 

Application Name: junos:FACEBOOK-MESSENGER                   

Application type: FACEBOOK-MESSENGER                      

Description: Facebook Messenger is a text and voice messaging application for mobile devices, and also a web application for desktop or mobile web browsers. Facebook Messenger provides both text chat and audio/video communication. On mobile devices, this plug-in classifies Audio flows, Video flows, as well as Text Chat-related flows. On the web application, when running Internet Explorer, this plug-in only classifies the browsing and chat flows. On all platforms, photos and file transfers are classified as facebook.

For the download of multimedia files on Facebook Messenger application, junos:FACEBOOK-ACCESS signature should be allowed in the security policy. But this will allow the Facebook application to work even if user is intended to block it.