Alpha2 Alphanumeric Mixedcase Encoder - Metasploit


This page contains detailed information about how to use the encoder/x86/alpha_mixed metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.

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Module Overview

Name: Alpha2 Alphanumeric Mixedcase Encoder
Module: encoder/x86/alpha_mixed
Source code: modules/encoders/x86/alpha_mixed.rb
Disclosure date: -
Last modification time: 2017-07-24 06:26:21 +0000
Supported architecture(s): x86
Supported platform(s): All
Target service / protocol: -
Target network port(s): -
List of CVEs: -

Encodes payloads as alphanumeric mixedcase text. This encoder uses SkyLined's Alpha2 encoding suite. A pure alpha encoder is impossible without having a register that points at or near the shellcode. In a default configuration the first few bytes at the beginning are an fnstenv getpc stub (the same as used in shikata_ga_nai) and thus are not alphanumeric. You can set BufferRegister for full alpha (see Encoder options for details).

Module Ranking and Traits

Module Ranking:

  • low: The exploit is nearly impossible to exploit (or under 50% success rate) for common platforms. More information about ranking can be found here.

Basic Usage

msf > use encoder/x86/alpha_mixed
msf encoder(alpha_mixed) > show targets
    ... a list of targets ...
msf encoder(alpha_mixed) > set TARGET target-id
msf encoder(alpha_mixed) > show options
    ... show and set options ...
msf encoder(alpha_mixed) > exploit

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Msfconsole Usage

Here is how the encoder/x86/alpha_mixed module looks in the msfconsole:

msf6 > use encoder/x86/alpha_mixed

msf6 encoder(x86/alpha_mixed) > show info

       Name: Alpha2 Alphanumeric Mixedcase Encoder
     Module: encoder/x86/alpha_mixed
   Platform: All
       Arch: x86
       Rank: Low

Provided by:
  pusscat <[email protected]>
  skylined <[email protected]>

Description:
  Encodes payloads as alphanumeric mixedcase text. This encoder uses 
  SkyLined's Alpha2 encoding suite. A pure alpha encoder is impossible 
  without having a register that points at or near the shellcode. In a 
  default configuration the first few bytes at the beginning are an 
  fnstenv getpc stub (the same as used in shikata_ga_nai) and thus are 
  not alphanumeric. You can set BufferRegister for full alpha (see 
  Encoder options for details).

Module Options

This is a complete list of options available in the encoder/x86/alpha_mixed module:

msf6 encoder(x86/alpha_mixed) > show options

Module options (encoder/x86/alpha_mixed):

   Name            Current Setting  Required  Description
   ----            ---------------  --------  -----------
   AllowWin32SEH   false            yes       Use SEH to determine the address of the stub (Windows only)
   BufferOffset    0                no        The offset to the buffer from the start of the register
   BufferRegister                   no        The register that points to the encoded payload

Advanced Options

Here is a complete list of advanced options supported by the encoder/x86/alpha_mixed module:

msf6 encoder(x86/alpha_mixed) > show advanced

Module advanced options (encoder/x86/alpha_mixed):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   VERBOSE    false            no        Enable detailed status messages
   WORKSPACE                   no        Specify the workspace for this module

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Error Messages

This module may fail with the following error messages:

Error Messages

Check for the possible causes from the code snippets below found in the module source code. This can often times help in identifying the root cause of the problem.

Unable to generate geteip code

Here is a relevant code snippet related to the "Unable to generate geteip code" error message:

56:	            Rex::Arch::X86::EAX
57:	          ])
58:	      else
59:	        res = Rex::Arch::X86.geteip_fpu(state.badchars, modified_registers)
60:	        if (not res)
61:	          raise EncodingError, "Unable to generate geteip code"
62:	        end
63:	      buf, reg, off = res
64:	      end
65:	    else
66:	      reg.upcase!

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See Also

Check also the following modules related to this module:

Authors

  • pusscat
  • skylined

Version

This page has been produced using Metasploit Framework version 6.1.24-dev. For more modules, visit the Metasploit Module Library.

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