Description

This article provides a way to use Enhanced Web Filtering (EWF) to block a specific HTTPS link within a website via custom objects.

For more information on basic SSL-proxy settings, refer to KB31122 - [SRX] Blocking HTTPS sites using EWF (Enhanced Web Filtering) [juniper.net] .
For more help on configuring Enhanced Web Filtering, refer to KB30867 - [SRX] How to configure Enhanced Web Filtering to block HTTPS traffic via custom objects [juniper.net]

Solution

From version Junos OS 12.3X48-D25 and above, all SRX series of devices (except vSRX) can integrate the SSL proxy with the EWF feature. 
From version Junos OS 15.1X49-D40 and above, any SRX can integrate the SSL proxy with the EWF feature. 

Configuration example:

[edit security utm]
root@SRX-240# show 
custom-objects {
    url-pattern {
        blacklist {
            value https://support.juniper.net;  <<<< User defined HTTPS blacklist
        }
    }
    custom-url-category {
        bad {
            value blacklist;
        }
    }
}
feature-profile {
    web-filtering {
        type juniper-enhanced;
        juniper-enhanced {
            server {
                host rp.cloud.threatseeker.com;
                port 80;
            }
            profile test {
                category {
                    bad {
                        action block;   <<<<< Block the specific link 
                    }
                }
                default permit;
                custom-block-message "This site is not allowed! GET BACK TO WORK!";
                fallback-settings {
                    default block;
                    server-connectivity log-and-permit;
                    timeout log-and-permit;
                    too-many-requests log-and-permit;
                }
            }
        }
    }
}
utm-policy Lab-test {
    web-filtering {
        http-profile test;
    }
}

Verification:

If a syslog is configured on the device, you can see the following logs:

set system syslog file blocked-sites any any
set system syslog file blocked-sites match WEBFILTER_URL_BLOCKED

root@SRX-240# run show log block 

Dec  4 08:40:58  SRX-240 RT_UTM: WEBFILTER_URL_BLOCKED: WebFilter: ACTION="URL Blocked" 192.168.1.1(52543)->66.129.230.17(443) CATEGORY="bad" REASON="BY_USER_DEFINED" PROFILE="test" URL= support.juniper.net OBJ=/ username N/A roles N/A
Dec  4 08:40:58  SRX-240 RT_UTM: WEBFILTER_URL_BLOCKED: WebFilter: ACTION="URL Blocked" 192.168.1.1(52542)->66.129.230.17(443) CATEGORY="bad" REASON="BY_USER_DEFINED" PROFILE="test" URL= support.juniper.net OBJ=/favicon.ico username N/A roles N/A