Skip to content

LFI and Blind SSRF via Avatar upload

High
SychO9 published GHSA-67c6-q4j4-hccg Aug 16, 2023

Package

composer flarum/core (Composer)

Affected versions

< 1.8.0

Patched versions

1.8.0
composer flarum/framework (Composer)
< 1.8.0
1.8.0

Description

Impact

The Flarum forum software is affected by a vulnerability that allows an attacker to conduct a Blind SSRF attack or disclose any file on the server, even with a basic user account on any Flarum forum. By uploading a file containing a URL and spoofing the MIME type, an attacker can manipulate the application to execute unintended actions. The vulnerability is due to the behavior of the intervention/image package, which attempts to interpret the supplied file contents as a URL, which then fetches its contents. This allows an attacker to exploit the vulnerability to perform SSRF attacks, disclose local file contents, or conduct a blind oracle attack.

Patches

This has been patched in Flarum v1.8.

Workarounds

As a temporary workaround for the SSRF aspect of the vulnerability, one can disable PHP's allow_url_fopen which will prevent the fetching of external files via URLs.

Credits

Adam Kues - Assetnote

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

CVE ID

CVE-2023-40033

Weaknesses

Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')

The PHP application receives input from an upstream component, but it does not restrict or incorrectly restricts the input before its usage in require, include, or similar functions. Learn more on MITRE.

Server-Side Request Forgery (SSRF)

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Learn more on MITRE.