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Display DLL forward information and forwarded addresses in Symbols table #2142

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zerosum0x0 opened this Issue Apr 7, 2019 · 0 comments

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commented Apr 7, 2019

Microsoft Windows [Version 10.0.17134.648]

I was working on something unrelated where I was grabbing functions out of Kernel32.dll, and I realized that the address that was taken out of the PE headers for HeapAlloc was invalid.

I was trying to debug why this address I was getting was wrong, and noticed that x64dbg was also resolving to the same incorrect address.

image

image

It's obvious there is no good going on at this address.

image

I wrote a program that did the basic following:

printf("%p\n", HeapAlloc);
printf("%p\n", GetProcAddress(GetModuleHandleA("Kernel32.dll"), "HeapAlloc"));

output:

76EC5D00
76EC5D00

image

This is WoW64 but same issue with the x64 library too.

Now it's very obvious this is a forwarded export...

dumpbin /exports "C:\Windows\system32\kernel32.dll" | findstr HeapAlloc
        843  34A          HeapAlloc (forwarded to NTDLL.RtlAllocateHeap)

I'm guessing if this is just a basic forwarding (non-api set crap) that x64dbg would already have code to resolve those and something else is happening?

--

Edit: Wild goose chases at 3:30 in the morning, it's a basic forwarder I thought my parser code I wrote ages ago handled.

I think that x64dbg should handle these case though and display something about it in the Symbols tab.

@zerosum0x0 zerosum0x0 changed the title HeapAlloc address incorrect in kernel32 export table Display DLL forward information and forwarded addresses in Symbols table Apr 7, 2019

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