Elastic Defend high stable eql

Network Activity from Modified Module

Identifies network activity from a module modified in memory. This may indicate a successful module stomping attack.

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Detection Logic

library where
  (
   (dll.name : "dnsapi.dll" and process.thread.Ext.call_stack_summary regex """ntdll.dll\
| iphlpapi.dll\
| [a-z0-9]+\.dll""" and
    process.thread.Ext.call_stack_summary != "ntdll.dll
| iphlpapi.dll
| jnitype3.dll" and
    _arraysearch(process.thread.Ext.call_stack, $entry,
                 stringcontains~($entry.symbol_info, substring(process.thread.Ext.call_stack_summary, 23, length(process.thread.Ext.call_stack_summary))) and ($entry.callsite_trailing_bytes : "?*" and $entry.allocation_private_bytes >= 100000))) or

   (dll.name : ("ws2_32.dll", "wininet.dll") and process.thread.Ext.call_stack_summary regex """ntdll.dll\
| kernelbase.dll\
| [a-z0-9]+\.dll""" and
    _arraysearch(process.thread.Ext.call_stack, $entry,
                 stringcontains~($entry.symbol_info, substring(process.thread.Ext.call_stack_summary, 25, length(process.thread.Ext.call_stack_summary))) and ($entry.callsite_trailing_bytes : "?*" and $entry.allocation_private_bytes >= 100000))) or

   (dll.name : "winhttp.dll" and process.thread.Ext.call_stack_summary regex """ntdll.dll\
| kernelbase.dll\
| wininet.dll\
| [a-z0-9]+\.dll""" and
    _arraysearch(process.thread.Ext.call_stack, $entry,
                 stringcontains~($entry.symbol_info, substring(process.thread.Ext.call_stack_summary, 37, length(process.thread.Ext.call_stack_summary))) and ($entry.callsite_trailing_bytes : "?*" and $entry.allocation_private_bytes >= 100000)))
   ) and
not _arraysearch(process.thread.Ext.call_stack, $entry,
                  $entry.callsite_trailing_bytes in ("9c6895de80184c890c244d89c94883ec0841558f042449bd81020000000000004c896c2408415d554889ed41535048b85f557f7b00000000415549bd45fa0985",
                                                     "9c5268d12b4248683616e700488914248f04245a48c704247e0400004881ec080000004c891c24514c89d94881ec080000004c890c244989c94d89cb41595948",
                                                     "e9186fffff0f85f8b1fefff7d3498bdce95856000048ffc0f8e9edcdfeff0f8548dbfeff66d3d6660fbcf1f949d1ed66c1f6076681e6a53d480fa5e6488bf3f5",
                                                     "4c8d25e0eeffff4489e121d94c89e54831dd4c8d3d38eeffff4489fa21da4d89fe4931de83f86f488d4c4d00498d1456480f44d1ffe2a6094f1ffaf803be2794"))

Field Validations

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