CVE-2021-39321

Sassy Social Share 3.3.23 - Object Injection

2021-10-21 16:05
Chloe Chamberland

Strategic Overview

Status
Patched in 3.3.24
Affected Plugin
Social Sharing Plugin – Sassy Social Share
Affected Version
3.3.23
CVSS
8.8High
Weakness type
CWE-502 · Deserialization of Untrusted Data
CVE
CVE-2021-39321
View all Social Sharing Plugin – Sassy Social Share vulnerabilities

At a glance

CVE-2021-39321 is a high-severity Deserialization of Untrusted Data vulnerability in the Social Sharing Plugin WordPress plugin, affecting versions 3.3.23. It carries a CVSS score of 8.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). The issue is fixed in version 3.3.24; sites on affected versions should update now. Disclosed October 2021, reported by Chloe Chamberland.

Vulnerability Overview

Version 3.3.23 of the Sassy Social Share WordPress plugin is vulnerable to PHP Object Injection via the wp_ajax_heateor_sss_import_config AJAX action due to deserialization of unvalidated user supplied inputs via the import_config function found in the ~/admin/class-sassy-social-share-admin.php file. This can be exploited by underprivileged authenticated users due to a missing capability check on the import_config function.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-502: Deserialization of Untrusted Data

Reaching this weakness in Social Sharing Plugin 3.3.23 takes a caller who can reach the endpoint. Deserialization of untrusted data means the application reconstructs objects from input a caller controls, letting the attacker choose which classes get instantiated and what their properties hold.

A workable chain turns deserialization into file writes, deletions or code execution, depending on what the loaded classes do in their magic methods. For Social Sharing Plugin the fix is 3.3.24: builds 3.3.23 are affected, anything from 3.3.24 onward is not.

Remediation

Update to version 3.3.24, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Social Sharing Plugin: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: Social Sharing Plugin 3.3.24 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-39321https://www.wordfence.com/threat-intel/vulnerabilities/id/ddb7b668-f023-427e-9ab5-90dc6d481028https://nvd.nist.gov/vuln/detail/CVE-2021-39321

Related records

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