CVE-2017-18491

Advanced Contact Us Form Builder for WordPress <= 4.0.5 - Reflected Cross-Site Scripting

2017-04-12 00:00

Strategic Overview

Status: Patched in 4.0.6
Affected Plugin: Contact Form by BestWebSoft – Advanced WP Contact Form Builder for WordPress
Affected Version: < 4.0.6
CVSS: 6.1Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2017-18491

View all Contact Form by BestWebSoft – Advanced WP Contact Form Builder for WordPress vulnerabilities

At a glance

CVE-2017-18491 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Contact Form by BestWebSoft WordPress plugin, affecting versions < 4.0.6. It carries a CVSS score of 6.1 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 4.0.6; sites on affected versions should update now. Disclosed April 2017, reported by Neven Birusk.

Vulnerability Overview

The Advanced Contact Us Form Builder for WordPress plugin for WordPress is vulnerable to Reflected Cross-Site Scripting in versions up to, and including, 4.0.5 due to insufficient input sanitization and output escaping on the 'category' parameter. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that execute in a victim's browser granted they can trick the user into performing an action such as clicking on a link.

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.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Contact Form by BestWebSoft < 4.0.6 carries this weakness at category, and reaching it takes a caller who can reach the endpoint. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For Contact Form by BestWebSoft the fix is 4.0.6: builds < 4.0.6 are affected, anything from 4.0.6 onward is not.

Remediation

Update to version 4.0.6, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Contact Form by BestWebSoft: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Contact Form by BestWebSoft 4.0.6 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2017-18491 https://www.wordfence.com/threat-intel/vulnerabilities/id/c7c36911-4afe-4ac7-9a76-7365bb86f81c https://nvd.nist.gov/vuln/detail/CVE-2017-18491

Related records

Same weakness class

Other vulnerabilities in Contact Form by BestWebSoft – Advanced WP Contact Form Builder for WordPress

CVSS Vector

6.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeChanged
ConfidentialityLow
IntegrityLow
AvailabilityNone

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