Citrix Content Collaboration: improper access control flaw under attack

What is affected

Citrix Content Collaboration is mostly run by companies, schools and public bodies, not on home computers. You are unlikely to have it yourself, but organisations that hold your data may. Breaches that start with flaws like this one are how personal data ends up leaked.

Citrix Content Collaboration contains an improper access control vulnerability that could allow an unauthenticated attacker to remotely compromise customer-managed ShareFile storage zones controllers.

What an attacker can do

This is a improper access control flaw. It lets an attacker perform actions or reach data that should be restricted to authorised users.

How it is reached

Over the internet or network

Access the attacker needs

No account needed

Does the victim have to do something?

No, works without the victim doing anything

What to do

1. At home: nothing to install. Keep your own devices updated and use a different password for every service, so that a breach at one organisation does not open your other accounts.
2. If you administer Citrix Content Collaboration at work: apply the vendor's fix or mitigation now and review logs for signs of compromise, because the flaw was being exploited before it was listed.
3. If the product is past its support date and no fix exists, take it off the internet or retire it.

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• support.citrix.comsupport.citrix.com/article/CTX559517/sharefile-storagezones-controller-security-update-for

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on August 16, 2023, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by September 6, 2023, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 97% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 99.9% of all scored vulnerabilities.

Its CVSS severity score is 9.8 out of 10 (critical), as recorded in the US National Vulnerability Database.

Technical description

A vulnerability has been discovered in the customer-managed ShareFile storage zones controller which, if exploited, could allow an unauthenticated attacker to remotely compromise the customer-managed ShareFile storage zones controller.