CVE-2024-52584

Executive Summary

CVE-2024-52584 is an authorization bypass vulnerability in Autolab, a course management service for auto-graded programming assignments. The flaw allows a Course Assistant (CA) to view or edit grades for any submission ID, even if they are not assigned as a CA for the class that owns the submission. The vulnerability stems from insufficient authorization checks in the endpoints, which only verify that the user has CA-level privileges in some class, but fail to confirm that the user is a CA for the specific class associated with the submission. This can lead to unauthorized grade tampering and data exposure. The vulnerability is present in Autolab version 3.0.1 and earlier, and is patched in version 3.0.2.

Supply Chain & Package Security

This vulnerability is not related to a package manager (NPM, PyPI, Go, Ruby) but is a direct application-level flaw in the Autolab Ruby on Rails application. The fix is applied via the application's source code repository.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
• Base Score: 8.1 (High)
• Attack Vector (AV): Network (N) – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – The attacker must have a valid CA account.
• User Interaction (UI): None (N) – No user interaction is required.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High (H) – Unauthorized access to grade data.
• Integrity (I): High (H) – Unauthorized modification of grades.
• Availability (A): None (N) – No impact on availability.

Threat Level: High. An authenticated CA can escalate their privileges to access and modify grades across all courses, undermining the integrity of the grading system.

Deep Dive & Mechanics

The vulnerability exists in the authorization logic of Autolab's API endpoints that handle grade viewing and editing. The application uses a role-based access control (RBAC) system where users can be assigned as Course Assistants (CAs) for specific courses. The flawed endpoints only check if the user has the course_assistant role in any course, rather than verifying that the user is a CA for the course that owns the submission.

Root Cause: The authorization check likely uses a method like current_user.has_role?(:course_assistant) which returns true if the user has the role in any context. The correct check should be current_user.has_role?(:course_assistant, @course) to ensure the role is scoped to the specific course.

Attack Scenario:

1. An attacker with a valid CA account for Course A logs in.
2. The attacker identifies a submission ID belonging to Course B (e.g., by guessing or enumerating IDs).
3. The attacker sends a request to the grade view/edit endpoint with the submission ID.
4. The server checks if the attacker is a CA (true, because they are a CA for Course A) and allows the request.
5. The attacker can now view or modify the grade for the submission in Course B.

Vulnerable vs. Patched Code

Vulnerable Code (Version 3.0.1):

# app/controllers/grades_controller.rb
def show
  submission = Submission.find(params[:id])
  authorize! :read, submission
  # ... render grade
end

# app/models/ability.rb
def initialize(user)
  # ...
  can :read, Submission do |submission|
    user.has_role?(:course_assistant) # Flawed: checks any course
  end
  can :update, Submission do |submission|
    user.has_role?(:course_assistant) # Flawed: checks any course
  end
end

Patched Code (Version 3.0.2):

# app/controllers/grades_controller.rb
def show
  submission = Submission.find(params[:id])
  authorize! :read, submission
  # ... render grade
end

# app/models/ability.rb
def initialize(user)
  # ...
  can :read, Submission do |submission|
    user.has_role?(:course_assistant, submission.course) # Fixed: scoped to course
  end
  can :update, Submission do |submission|
    user.has_role?(:course_assistant, submission.course) # Fixed: scoped to course
  end
end

The patch adds the submission.course argument to the has_role? call, ensuring that the CA role is verified against the specific course that owns the submission.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A valid Autolab account with CA privileges for at least one course.
• Knowledge of a submission ID from another course (can be enumerated or guessed).

Exploitation Steps:

1. Identify Target: Find a submission ID from a course you are not a CA for. This can be done by observing the URL pattern (e.g., /submissions/12345) or by brute-forcing IDs.
2. Craft Request: Send a GET or POST request to the grade endpoint with the target submission ID.

   # View grade
   curl -X GET "https://autolab.example.com/submissions/12345/grade" \
     -H "Cookie: session=<your_session_cookie>"
   
   # Edit grade
   curl -X POST "https://autolab.example.com/submissions/12345/grade" \
     -H "Cookie: session=<your_session_cookie>" \
     -d "grade=100&feedback=Excellent"
   

3. Verify: Check the response to confirm unauthorized access or modification.

Note: No public exploit code is available for this CVE.

Blue Team (Detection & Prevention)

Detection:

• Monitor for unusual access patterns to grade endpoints from users who are not CAs for the associated course.
• Log and alert on failed authorization attempts (HTTP 403) followed by successful access to the same resource.
• Use the detection rules provided in the Detection Engineering section.

Prevention:

• Apply the patch by upgrading to Autolab 3.0.2 or later.
• Implement additional logging for all grade-related actions.
• Conduct regular audits of CA assignments and access logs.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests to /submissions/[0-9]+/grade from users with CA role but not assigned to the submission's course.
  • Unusual patterns of grade changes (e.g., bulk modifications, changes to 100 or 0).
• Logs:
  • Successful grade view/edit actions for submissions where the user is not a CA for the course.
  • Repeated attempts to access grade endpoints with different submission IDs.
• System:
  • Unexpected changes in grade data for courses.
  • User accounts with CA role accessing submissions outside their assigned courses.

Detection Engineering

YARA Rule

rule CVE_2024_52584_Autolab_Authorization_Bypass {
    meta:
        description = "Detects potential exploitation of CVE-2024-52584 in Autolab logs"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-52584"
    strings:
        $grade_endpoint = "/submissions/" nocase
        $grade_action = "/grade" nocase
        $ca_role = "course_assistant" nocase
    condition:
        all of them
}

Sigma Rule

title: Autolab CVE-2024-52584 Authorization Bypass
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects unauthorized grade access attempts in Autolab
author: Valters IT
date: 2024/01/01
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-52584
logsource:
    category: application
    product: autolab
detection:
    selection:
        http_method: GET or POST
        url_path|contains: "/submissions/"
        url_path|endswith: "/grade"
    condition: selection
falsepositives:
    - Legitimate CA actions for their assigned courses
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2024-52584 Autolab Grade Access Attempt";
    flow:to_server,established;
    content:"/submissions/"; http_uri;
    content:"/grade"; http_uri;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Upgrade Autolab: Update to version 3.0.2 or later immediately.

   git pull origin master
   bundle install
   rails db:migrate
   

2. Verify Patch: Confirm that the authorization checks now include the course scope.
3. Audit Logs: Review recent access logs for signs of exploitation.

Long-Term Mitigations:

• Implement additional authorization checks at the controller level (defense in depth).
• Use a centralized authorization library like Pundit or CanCanCan with proper scoping.
• Conduct regular security training for developers on RBAC best practices.
• Monitor for similar vulnerabilities in other parts of the application.

Workarounds: No known workarounds are available. The only fix is to apply the patch.

Valters IT