48 lines
No EOL
1.9 KiB
Text
48 lines
No EOL
1.9 KiB
Text
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=927
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The DxgkDdiEscape handler for escape code 0x100010b looks like:
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char escape_100010b(NvMiniportDeviceContext *miniport_context, HANDLE handle, unsigned int idx)
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{
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PVOID *Object;
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if ( !handle )
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do_debug_thingo();
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Object = (PVOID *)&miniport_context->UNKNOWN[8 * idx + 22696];
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if ( !ObReferenceObjectByHandle(handle_, SYNCHRONIZE, )ExEventObjectType, UserMode, Object, 0i64) )
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{
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result = 0;
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if ( *Object )
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result = UserMode;
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}
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return result;
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}
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It essentially takes in a user mode event handle from userspace, and calls
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ObReferenceObjectByHandle on it, writing the object pointer to |Object|. Note
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that the kernel implementation of ObReferenceObjectByHandle always begins with
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writing NULL to this pointer regardless of whether or not the handle is valid.
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|Object| is calculated using a user provided index that is not bounds checked,
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leading to OOB write of either NULL or the KEVENT pointer:
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Object = (PVOID *)&miniport_context_->UNKNOWN[8 * idx + 22696];
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The attached PoC causes the following crashing context on Win x64 372.54:
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PAGE_FAULT_IN_NONPAGED_AREA (50)
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...
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rax=ffffe0025ea28f50 rbx=0000000000000000 rcx=0000000000000000
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rdx=0000000000100000 rsi=0000000000000000 rdi=0000000000000000
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rip=fffff801d8f3daf5 rsp=ffffd000203deda0 rbp=0000000000000001
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r8=ffffe000506d4b50 r9=ffffe000524fb201 r10=0000000000000000
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r11=ffffd000203df370 r12=0000000000000000 r13=0000000000000000
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r14=0000000000000000 r15=0000000000000000
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iopl=0 nv up ei pl zr na po nc
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nt!ObReferenceObjectByHandleWithTag+0x45:
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fffff801`d8f3daf5 488908 mov qword ptr [rax],rcx ds:ffffe002`5ea28f50=????????????????
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To reproduce, compile as a x64 executable and run (requires WDK for D3DKMTEscape).
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Proof of Concept:
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https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/40661.zip |