CVE-2021-24663

Simple Schools Staff Directory <= 1.1 - Authenticated (Admin+) Arbitrary File Upload

2021-08-23 00:00
Chuang LI

Strategic Overview

Status
Unpatched
Affected Version
<= 1.1
CVSS
7.2High
Weakness type
CWE-434 · Unrestricted Upload of File with Dangerous Type
CVE
CVE-2021-24663
View all Simple Schools Staff Directory vulnerabilities

At a glance

CVE-2021-24663 is a high-severity Unrestricted Upload of File with Dangerous Type vulnerability in the Simple Schools Staff Directory WordPress plugin, affecting versions <= 1.1. It carries a CVSS score of 7.2 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires an authenticated account at Admin level or above. No fixed release has been reported yet; treat installations running this software as exposed. Disclosed August 2021, reported by Chuang LI.

Vulnerability Overview

The Simple Schools Staff Directory WordPress plugin through 1.1 does not validate uploaded logo pictures to ensure that are indeed images, allowing high privilege users such as admin to upload arbitrary file like PHP, leading to RCE

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-434: Unrestricted Upload of File with Dangerous Type

Reaching this weakness in Simple Schools Staff Directory <= 1.1 takes an account at Admin level or above. An unrestricted file upload lets a caller store a file whose type or destination the application does not properly constrain.

If an uploaded file lands anywhere the server will execute, the flaw becomes remote code execution and the site should be treated as fully compromised. No fixed build of this plugin is recorded for Simple Schools Staff Directory yet, so installs running <= 1.1 stay exposed until the vendor ships one.

Remediation

No known patch available. Please review the vulnerability's details in depth and employ mitigations based on your organization's risk tolerance. It may be best to uninstall the affected software and find a replacement.

How does WordSec protect against this?

An attacker needs Admin access first, so the firewall sees the attempt as traffic from a logged-in account: 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. No patched version is recorded yet, which is the case where a filtering layer matters most, because there is nothing to update to.

  • Firewall
  • Scanner
  • Alerts

External References

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