Safety researchers are monitoring what they are saying is the “mass exploitation” of a safety vulnerability that makes it potential to take full management of servers operating ownCloud, a extensively used open-source filesharing server app.

The vulnerability, which carries the utmost severity score of 10, makes it potential to acquire passwords and cryptographic keys permitting administrative management of a weak server by sending a easy Internet request to a static URL, ownCloud officers warned final week. Inside 4 days of the November 21 disclosure, researchers at safety agency Greynoise mentioned, they started observing “mass exploitation” of their honeypot servers, which masqueraded as weak ownCloud servers to trace makes an attempt to take advantage of the vulnerability. The variety of IP addresses sending the online requests has slowly risen since then. On the time this submit went dwell on Ars, it had reached 13.

Spraying the Web

“We’re seeing hits to the particular endpoint that exposes delicate data, which might be thought-about exploitation,” Glenn Thorpe, senior director of safety analysis & detection engineering at Greynoise, mentioned in an interview on Mastodon. “In the meanwhile, we have seen 13 IPs which can be hitting our unadvertised sensors, which signifies that they’re just about spraying it throughout the web to see what hits.”

CVE-2023-49103 resides in variations 0.2.0 and 0.3.0 of graphapi, an app that runs in some ownCloud deployments, relying on the way in which they’re configured. A 3rd-party code library utilized by the app supplies a URL that, when accessed, reveals configuration particulars from the PHP-based surroundings. In final week’s disclosure, ownCloud officers mentioned that in containerized configurations—akin to these utilizing the Docker virtualization device—the URL can reveal information used to log into the weak server. The officers went on to warn that merely disabling the app in such circumstances wasn’t adequate to lock down a weak server.

The ownCloud advisory defined:

The “graphapi” app depends on a third-party library that gives a URL. When this URL is accessed, it reveals the configuration particulars of the PHP surroundings (phpinfo). This data contains all of the surroundings variables of the webserver. In containerized deployments, these surroundings variables could embody delicate information such because the ownCloud admin password, mail server credentials, and license key.

It’s vital to emphasise that merely disabling the graphapi app doesn’t eradicate the vulnerability. Moreover, phpinfo exposes varied different probably delicate configuration particulars that might be exploited by an attacker to assemble details about the system. Due to this fact, even when ownCloud is just not operating in a containerized surroundings, this vulnerability ought to nonetheless be a trigger for concern.

Not all safety practitioners regard the vulnerability as posing a widespread risk, the way in which different vulnerabilities—most not too long ago the vulnerability tracked as CVE-2023-4966 and CitrixBleed—have. Particularly, impartial researcher Kevin Beaumont has famous that the CVE-2023-49103 vulnerability wasn’t launched till 2020, isn’t exploitable by default, and was solely launched in containers in February.

“I don’t suppose anyone else truly checked if the weak function is enabled,” he mentioned in an interview. What’s extra, an ownCloud Internet web page confirmed graphapi had fewer than 900 installs on the time this submit went dwell on Ars. ownCloud officers didn’t instantly reply to an e-mail in search of technical particulars of the vulnerability and the exact circumstances required for it to be exploited.

Given the potential risk posed by CVE-2023-49103, there’s nonetheless room for reputable concern. In line with safety group Shadowserver, a latest scan revealed greater than 11,000 IP addresses internet hosting ownCloud servers, led by addresses in Germany, the US, France, Russia, and Poland. Even when solely a small fraction of the servers are weak, the potential for hurt is actual.

“Not surprisingly given ease of exploitation we have now began seeing OwnCloud CVE-2023-49103 makes an attempt,” Shadowserver officers wrote. “This can be a CVSS 10 disclosure of delicate credentials & configs in containerized deployments. Please comply with ownCloud advisory mitigation steps.”

Extra high-severity ownCloud vulnerabilities

One more reason for concern: ownCloud not too long ago mounted two different high-severity vulnerabilities, together with CVE-2023-94105, which has a severity score of 9.8. The flaw permits for an authentication bypass within the WebDAV API utilizing pre-signed URLs. Hackers can exploit it “to entry, modify or delete any file with out authentication if the username of the sufferer is understood and the sufferer has no signing-key configured (which is the default),” ownCloud officers warned. The vulnerability impacts the WebDAV API in ownCloud variations 10.6.0 to 10.13.0.

A 3rd vulnerability tracked as CVE-2023-94104 is a subdomain validation bypass flaw with a severity score of 8.7. Hackers can exploit it utilizing a redirect URL, making it potential to redirect callbacks to a website managed by the attacker.

To repair the ownCloud vulnerability beneath exploitation, ownCloud suggested customers to:

Delete the file owncloud/apps/graphapi/vendor/microsoft/microsoft-graph/checks/GetPhpInfo.php. Moreover, we disabled the phpinfo perform in our docker-containers. We are going to apply varied hardenings in future core releases to mitigate related vulnerabilities.

We additionally advise to vary the next secrets and techniques:
– ownCloud admin password
– Mail server credentials
– Database credentials
– Object-Retailer/S3 access-key

Whereas there aren’t any studies of the opposite two vulnerabilities being actively exploited, customers ought to comply with the directions ownCloud has offered right here and right here.

In latest months, vulnerabilities in file sharing apps akin to WS-FTP server, MOVEit, and IBM Aspera Faspex, and GoAnywhere MFT have enabled the compromise of 1000’s of enterprise networks. Anybody who ignores the risk posed by the not too long ago mounted ownCloud flaws does so at their very own peril.