Vulnerability identifier: #VU14439

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2017-1000600, CVE-2018-1000773

CWE-ID: CWE-502

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
WordPress
Web applications / CMS

Vendor: WordPress.ORG

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to insecure deserialization of data passed as an image file and then executed via the "phar://" stream wrapper within the "wp_get_attachment_thumb_file" function in "/wpincludes/post.php" script. A remote authenticated attacker with ability to create/edit posts can upload a malicious image and execute arbitrary PHP code on vulnerable system. 

Mitigation
Install update from vendor's website.

Vulnerable software versions

WordPress: 4.9 - 4.9.8

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External links
http://cdn2.hubspot.net/hubfs/3853213/us-18-Thomas-It's-A-PHP-Unserialization-Vulnerability-Jim-But-Not-As-We-....pdf

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated privileged user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.