CVE-2020-35949

Quiz and Survey Master <= 7.0.0 - Arbitrary File Upload

2020-08-03 00:00
Chloe Chamberland

Strategic Overview

Status
Patched in 7.0.1
Affected Plugin
Quiz and Survey Master (QSM) – Quiz Maker & Survey Maker
Affected Version
< 7.0.1
CVSS
9.8Critical
Weakness type
CWE-434 · Unrestricted Upload of File with Dangerous Type
CVE
CVE-2020-35949
View all Quiz and Survey Master (QSM) – Quiz Maker & Survey Maker vulnerabilities

At a glance

CVE-2020-35949 is a critical-severity Unrestricted Upload of File with Dangerous Type vulnerability in the Quiz and Survey Master (QSM) WordPress plugin, affecting versions < 7.0.1. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 7.0.1; sites on affected versions should update now. Disclosed August 2020, reported by Chloe Chamberland.

Vulnerability Overview

An issue was discovered in the Quiz and Survey Master plugin before 7.0.1 for WordPress. It made it possible for unauthenticated attackers to upload arbitrary files and achieve remote code execution. If a quiz question could be answered by uploading a file, only the Content-Type header was checked during the upload, and thus the attacker could use text/plain for a .php file.

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 privileges on the target site, 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 Quiz and Survey Master (QSM) < 7.0.1 takes a caller who can reach the endpoint. 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. For Quiz and Survey Master (QSM) the fix is 7.0.1: builds < 7.0.1 are affected, anything from 7.0.1 onward is not.

Remediation

Update to version 7.0.1, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Quiz and Survey Master (QSM): 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: Quiz and Survey Master (QSM) 7.0.1 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2020-35949https://www.wordfence.com/threat-intel/vulnerabilities/id/bfd93c33-4672-4914-b052-7bea283ef60chttps://nvd.nist.gov/vuln/detail/CVE-2020-35949

Related records

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