The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Below is a copy: Chrome V8 Turbofan JSCallReducer::ReduceArrayIndexOfIncludes Failed Check
v8: turbofan: JSCallReducer::ReduceArrayIndexOfIncludes fails to insert Map checks
Since commit https://chromium.googlesource.com/v8/v8.git/+/c22bb466d8934685d897708119543d099b9d2a9a turbofan supports inlining calls to array.includes and array.indexOf. The logic of the function is roughly:
1. Check the set of possible Maps of the array type (with NodeProperties::InferReceiverMaps).
2. If they are all fast arrays, find the correct CSA builtin to handle the fast path (`Callable const callable = search_variant == SearchVariant::kIndexOf ? GetCallableForArrayIndexOf(kind, isolate()) : GetCallableForArrayIncludes(kind, isolate());`).
3. Load the array length and call the builtin. The builtin will assume that the array is a FastArray with packed (dense) elements and directly search linearly through the backing memory.
The issue here is that NodeProperties::InferReceiverMaps doesn't necessarily guarantee that the object will always have the inferred Map. In case it can't prove that the objects will always have the inferred Maps it will return kUnreliableReceiverMaps:
// Walks up the {effect} chain to find a witness that provides map
// information about the {receiver}. Can look through potentially
// side effecting nodes.
enum InferReceiverMapsResult {
kNoReceiverMaps, // No receiver maps inferred.
kReliableReceiverMaps, // Receiver maps can be trusted.
kUnreliableReceiverMaps // Receiver maps might have changed (side-effect),
// but instance type is reliable.
};
static InferReceiverMapsResult InferReceiverMaps(
JSHeapBroker* broker, Node* receiver, Node* effect,
ZoneHandleSet<Map>* maps_return);
In which case the caller is responsible for guarding any optimizations based on the inferred Maps (e.g. by adding MapChecks). However, in this case the calling function fails to do so. As such, if the array is changed to dictionary mode before the inlined function call, the CSA builtin will read data out-of-bounds.
The following sample, found through fuzzing, triggers this case:
function v7(v8,v11) {
function v14(v15,v16) { }
// Transition to dictionary mode in the final invocation.
const v17 = v11.__defineSetter__(v8, v14);
// Will then read OOB.
const v18 = v11.includes(1234);
return v18;
}
v7([], []);
v7([], []);
%OptimizeFunctionOnNextCall(v7);
v7([], []);
const v57 = v7(String(0x1000000), []);
Note: the commit introducing this vulnerability does not appear to be included in the stable Chrome release yet.
This bug is subject to a 90 day disclosure deadline. After 90 days elapse
or a patch has been made broadly available (whichever is earlier), the bug
report will become visible to the public.
Found by: [email protected]
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