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Stored XSS allowing token theft via crafted SVG

High
nrobinaubertin published GHSA-96fx-5rqv-jfxh Oct 31, 2024

Package

docker zusam/zusam (Docker)

Affected versions

<= 0.5.5

Patched versions

0.5.6

Description

Summary

Specially crafted SVG files uploaded to the service as images allow for unrestricted script execution on (raw) image load. With certain payloads, theft of the target user’s long-lived session token is possible.

Note that Zusam, at the time of writing, uses a user’s static API key as a long-lived session token, and these terms can be used interchangeably on the platform. This session token/API key remains valid indefinitely, so long as the user doesn’t expressly request a new one via their Settings page.

Basic Proof of Concept

<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns="http://www.w3.org/2000/svg" onload="alert(localStorage.getItem('apiKey'));">
  <rect width="100%" height="100%" fill="white"/>
  <text x="10" y="20" font-size="16" fill="black">Source: https://pfeister.dev</text>
</svg>
Zusam-SVG-XSS.mp4

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
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
Low

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:N/UI:R/S:C/C:H/I:L/A:L

CVE ID

CVE-2024-51492

Weaknesses

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

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

Credits