CVE-2022-2421

Due to improper type validation in attachment parsing the Socket.io js library, 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.

Due to improper type validation in attachment parsing the Socket.io js library, 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.

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: ```js 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: ```js 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: ```js 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}]` ```js 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}]` ```js 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"}]` ```js 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"}]` ```js 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](https://github.com/socketio/socket.io/commit/9890b036cf942f6b6ad2afeb6a8361c32cd5d528)) | Yes :heavy_check_mark: | | `4.1.3...4.5.1` | `~4.0.4` ([ref](https://github.com/socketio/socket.io/commit/7c44893d7878cd5bba1eff43150c3e664f88fb57)) | Yes :heavy_check_mark: | | `3.0.5...4.1.2` | `~4.0.3` ([ref](https://github.com/socketio/socket.io/commit/752dfe3b1e5fecda53dae899b4a39e6fed5a1a17)) | Yes :heavy_check_mark: | | `3.0.0...3.0.4` | `~4.0.1` ([ref](https://github.com/socketio/socket.io/commit/1af3267e3f5f7884214cf2ca4d5282d620092fb0)) | Yes :heavy_check_mark: | | `2.3.0...2.5.0` | `~3.4.0` ([ref](https://github.com/socketio/socket.io/commit/cf39362014f5ff13a17168b74772c43920d6e4fd)) | 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](https://github.com/socketio/socket.io-client/commit/b862924b7f1720979e5db2f0154906b305d420e3)) | Yes :heavy_check_mark: | | `4.3.0...4.4.1` | `~4.1.1` ([ref](https://github.com/socketio/socket.io-client/commit/91b948b8607166fcc79f028a6428819277214188)) | No, but the impact is very limited | | `3.1.0...4.2.0` | `~4.0.4` ([ref](https://github.com/socketio/socket.io-client/commit/5d9b4eb42b1f5778e6f033096694acb331b132c4)) | Yes :heavy_check_mark: | | `3.0.5` | `~4.0.3` ([ref](https://github.com/socketio/socket.io-client/commit/cf9fc358365cc15a41260a51dc186c881bf086ca)) | Yes :heavy_check_mark: | | `3.0.0...3.0.4` | `~4.0.1` ([ref](https://github.com/socketio/socket.io-client/commit/b7e07ba633ceb9c1dc94cc894c10b9bfca536c7a)) | Yes :heavy_check_mark: | | `2.2.0...2.5.0` | `~3.3.0` ([ref](https://github.com/socketio/socket.io-client/commit/06e9a4ca2621176c30c352b2ba8b34fa42b8d0ba)) | Yes :heavy_check_mark: |

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: ```js 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: ```js 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: ```js 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}]` ```js 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}]` ```js 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"}]` ```js 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"}]` ```js 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](https://github.com/socketio/socket.io/commit/9890b036cf942f6b6ad2afeb6a8361c32cd5d528)) | Yes :heavy_check_mark: | | `4.1.3...4.5.1` | `~4.0.4` ([ref](https://github.com/socketio/socket.io/commit/7c44893d7878cd5bba1eff43150c3e664f88fb57)) | Yes :heavy_check_mark: | | `3.0.5...4.1.2` | `~4.0.3` ([ref](https://github.com/socketio/socket.io/commit/752dfe3b1e5fecda53dae899b4a39e6fed5a1a17)) | Yes :heavy_check_mark: | | `3.0.0...3.0.4` | `~4.0.1` ([ref](https://github.com/socketio/socket.io/commit/1af3267e3f5f7884214cf2ca4d5282d620092fb0)) | Yes :heavy_check_mark: | | `2.3.0...2.5.0` | `~3.4.0` ([ref](https://github.com/socketio/socket.io/commit/cf39362014f5ff13a17168b74772c43920d6e4fd)) | 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](https://github.com/socketio/socket.io-client/commit/b862924b7f1720979e5db2f0154906b305d420e3)) | Yes :heavy_check_mark: | | `4.3.0...4.4.1` | `~4.1.1` ([ref](https://github.com/socketio/socket.io-client/commit/91b948b8607166fcc79f028a6428819277214188)) | No, but the impact is very limited | | `3.1.0...4.2.0` | `~4.0.4` ([ref](https://github.com/socketio/socket.io-client/commit/5d9b4eb42b1f5778e6f033096694acb331b132c4)) | Yes :heavy_check_mark: | | `3.0.5` | `~4.0.3` ([ref](https://github.com/socketio/socket.io-client/commit/cf9fc358365cc15a41260a51dc186c881bf086ca)) | Yes :heavy_check_mark: | | `3.0.0...3.0.4` | `~4.0.1` ([ref](https://github.com/socketio/socket.io-client/commit/b7e07ba633ceb9c1dc94cc894c10b9bfca536c7a)) | Yes :heavy_check_mark: | | `2.2.0...2.5.0` | `~3.3.0` ([ref](https://github.com/socketio/socket.io-client/commit/06e9a4ca2621176c30c352b2ba8b34fa42b8d0ba)) | Yes :heavy_check_mark: |

Debido a una incorrecta comprobación de tipos en el análisis de archivos adjuntos de la biblioteca js Socket.io, es posible sobrescribir el objeto _placeholder, lo que permite a un atacante colocar referencias a funciones en lugares arbitrarios en el objeto de consulta resultante