Prototype pollution finder tool for javascript. pp-finder lets you find prototype pollution candidates in your code. The main purpose of this tool is to help hackers in there prototype pollution researchs by highlighting potential candidate in the source code.
For instance, the following candidate will be highlighted by pp-finder:
if (options.exec) child_process.exec(options.exec);$ npm install -g pp-finderFor instance, let's find candidates in the popular express library:
$ mkdir -p target/express
$ cd target/express
$ yarn add express
$ # now write a very basic express application
To hunt for prototype pollution gadgets, pp-finder will parse the javascript source code of every file it finds in the provided directory.
It will copy the input directory into a new one with an updated version of the sources.
$ pp-finder hook ./target/express/node_modulesFrom now, if you run the application, it will output all the available candidates:
[PP][IsIn "colors"] node_modules/debug/src/node.js:76:22
[PP][ForIn] node_modules/safer-buffer/safer.js:12:13
[PP][IsIn "colors"] node_modules/debug/src/node.js:76:22
[PP][IsIn "colors"] node_modules/debug/src/node.js:76:22
[PP][IsIn "colors"] node_modules/debug/src/node.js:76:22
[PP][Prop noDeprecation] node_modules/depd/index.js:154:15
[...]
Example app listening on port 3000
Now, if you issue a request to that server, even more candidate show up:
[PP][Prop params] node_modules/express/lib/router/index.js:156:26
[PP][Prop baseUrl] node_modules/express/lib/router/index.js:157:23
[PP][Elem "baseUrl"] node_modules/express/lib/router/index.js:637:19
[PP][Elem "next"] node_modules/express/lib/router/index.js:637:19
[PP][Elem "params"] node_modules/express/lib/router/index.js:637:19
[...]
Add pp-finder hooks to a file or directory.
This will create a backup of each file in ~/.local/share/pp-finder
$ pp-finder hook --help PP-Finder hook
> Instrument a javascript project
ARGUMENTS:
<Path> - Path of the file or directory to instrument
OPTIONS:
--name, -n <str> - Wrapper name, (default "ø") [optional]
FLAGS:
--help, -h - show helpHook a file or directory,
Restore the backup (if available) for a file or directory
PP-Finder restore
> Remove pp-finder hooks from a javascript file or directory
ARGUMENTS:
<Path> - Path of the file or directory to restore
FLAGS:
--help, -h - show helpThis is moslty for developement purpose, restore and rehook a file / directory
Remove all backups
PP-Finder purge
> Purge all backups
ARGUMENTS:
[path] - Path of the file or directory to remove from the backup [optional]
FLAGS:
--help, -h - show help
You can configure the behaviour of PP finder using env variable:
PPF_LOG_ONCE=true => Log each gadget only once PPF_NO_COLOR=true => Remove the coloring of the output PPF_OUTPUT_FILE => Write the output to a file instead of stdout
Tests indicate what the library handles in terms of AST visitors:
❯ yarn run test
$ mocha test -r ts-node/register 'test/**/*.test.ts'
Hooks
PropertyAccessExpression
✔ Pollutable | ({}).y
✔ Not Pollutable | ({y: 42}).y
✔ Not Pollutable | (Object.create(null)).y
✔ Pollutable | ({y: {}}).y.z
ElementAccessExpression
✔ Pollutable | ({})['y']
✔ Not Pollutable | ({y: 42})['y']
✔ Not Pollutable | (Object.create(null))['y']
✔ Pollutable | ({y: {}})['y']['z']
ForInStatement
✔ Pollutable | for(let y in ({})){}
✔ Not Pollutable | for(let y in (Object.create(null))){}
ArrowFunctionDeclaration
✔ Pollutable | (({y}) => (0))({})
✔ Pollutable | (({y}, a, {z}) => (0))({}, 0, {})
✔ Pollutable | (({y: z}) => (0))({})
FunctionDeclaration
✔ Pollutable | function f({y}){return};f({})
✔ Pollutable | function f({y}, a, {z}){return};f({}, 42, {})
✔ Pollutable | function f({y: z}){return};f({})
✔ Pollutable | function f({['y']: z}){return};f({})
FunctionExpression
✔ Pollutable | (function ({y}){return})({})
✔ Pollutable | (function ({y}, a, {z}){return})({}, 0, {})
✔ Pollutable | (function ({y: z}){return})({})
✔ Pollutable | (function ({['y']: z}){return})({})
InExpression
✔ Pollutable | ("y" in {})
✔ Not Pollutable | ("y" in {y: 42})
✔ Not Pollutable | ("y" in Object.create(null))
ObjectLiteral
✔ Pollutable | ({y} = {});
✔ Pollutable | ({y: {z}} = {y: {}});
✔ Not Pollutable | ({y} = {y: 42});
✔ Not Pollutable | ({y} = Object.create(null));
✔ Pollutable | ({['y']: y} ={});
VariableDeclaration
✔ Pollutable | const {y} = {};
✔ Pollutable | const {y} = {}, {z} = {};
✔ Pollutable | const {y: {z}} = {y: {}};
✔ Not Pollutable | const {y} = {y: 42};
✔ Pollutable | const {['y']: y} ={};
✔ Not Pollutable | const {y} = Object.create(null);
✔ Pollutable | let z; const {y} = {z} = {};
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