alpha_mixed encoding not alpha

[tyronmiller at gmail.com (Ty Miller)]

Hi guys,

I didn't get a response on this one. If anyone has any comments or
suggestions relating to the email below, please shoot em through.

Thanks,
Ty


On Sun, Jun 29, 2008 at 1:18 PM, Ty Miller <tyronmiller at gmail.com> wrote:

> Hey guys,
>
> I've been messing around with alphanumeric shellcode encoding lately. I
> tried to generate some mixed alpha encoded shellcode via the MSF3.1 web
> interface using;
> - "Windows Execute Command" payload
> - command "dir"
> - no filtered characters since they're encoded anyway
> - "x86/alpha_mixed" encoder
>
> This generates the shellcode below. Alpha chars should be between 0x41 to
> 0x5a for uppercase and 0x61 to 0x7a for lowercase (and 0x30 - 0x39 for
> numeric), meaning the following shellcode isn't alpha characters only since
> it starts with "0xdb".
>
> Can you please let me know what I am doing wrong, or whether its a bug?
>
> Thanks,
> Ty
>
>
> /*
>  * windows/exec - 293 bytes
>  * http://www.metasploit.com
>  * Encoder: x86/alpha_mixed
>  * EXITFUNC=seh, CMD=dir
>  */
> unsigned char buf[] =
> "\xdb\xc8\xd9\x74\x24\xf4\x5b\x53\x59\x49\x49\x49\x49\x49\x49"
> "\x49\x49\x49\x43\x43\x43\x43\x43\x43\x43\x37\x51\x5a\x6a\x41"
> "\x58\x50\x30\x41\x30\x41\x6b\x41\x41\x51\x32\x41\x42\x32\x42"
> "\x42\x30\x42\x42\x41\x42\x58\x50\x38\x41\x42\x75\x4a\x49\x4b"
> "\x4c\x4d\x38\x47\x34\x43\x30\x45\x50\x43\x30\x4c\x4b\x51\x55"
> "\x47\x4c\x4c\x4b\x43\x4c\x45\x55\x44\x38\x45\x51\x4a\x4f\x4c"
> "\x4b\x50\x4f\x45\x48\x4c\x4b\x51\x4f\x47\x50\x45\x51\x4a\x4b"
> "\x47\x39\x4c\x4b\x46\x54\x4c\x4b\x43\x31\x4a\x4e\x50\x31\x49"
> "\x50\x4c\x59\x4e\x4c\x4d\x54\x49\x50\x42\x54\x43\x37\x49\x51"
> "\x49\x5a\x44\x4d\x43\x31\x49\x52\x4a\x4b\x4c\x34\x47\x4b\x51"
> "\x44\x46\x44\x44\x44\x42\x55\x4d\x35\x4c\x4b\x51\x4f\x51\x34"
> "\x45\x51\x4a\x4b\x43\x56\x4c\x4b\x44\x4c\x50\x4b\x4c\x4b\x51"
> "\x4f\x45\x4c\x45\x51\x4a\x4b\x4c\x4b\x45\x4c\x4c\x4b\x45\x51"
> "\x4a\x4b\x4b\x39\x51\x4c\x46\x44\x45\x54\x48\x43\x51\x4f\x46"
> "\x51\x4c\x36\x45\x30\x51\x46\x42\x44\x4c\x4b\x47\x36\x46\x50"
> "\x4c\x4b\x51\x50\x44\x4c\x4c\x4b\x42\x50\x45\x4c\x4e\x4d\x4c"
> "\x4b\x45\x38\x43\x38\x4d\x59\x4b\x48\x4d\x53\x49\x50\x43\x5a"
> "\x46\x30\x43\x58\x4c\x30\x4d\x5a\x45\x54\x51\x4f\x42\x48\x4a"
> "\x38\x4b\x4e\x4c\x4a\x44\x4e\x50\x57\x4b\x4f\x4b\x57\x43\x54"
> "\x43\x59\x42\x52\x45\x50\x41\x41";
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