EVT files are Windows Event Log files written by older Windows
operating systems (2000, XP, 2003). They are used as binary log
files by several major Windows subsystems and
applications. Typically, several of them can be found in
%WINDIR%\system32\config directory:
AppEvent.evtSysEvent.evtSecEvent.evtAlternatively, one can export any system event log as distinct .evt file using relevant option in Event Viewer application.
A Windows application can submit an entry into these logs using ReportEventA function of Windows API.
Internally, EVT files consist of a fixed-size header and event records. There are several usage scenarios (non-wrapping vs wrapping log files) which result in slightly different organization of records.
This page hosts a formal specification of Windows Event Log (EVT) using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.
The Python runtime library can be installed from PyPI:
python3 -m pip install kaitaistructParse a local file and get structure in memory:
data = WindowsEvtLog.from_file("path/to/local/file.evt")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = WindowsEvtLog(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.header # => get header
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
from enum import Enum
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 9):
raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))
class WindowsEvtLog(KaitaiStruct):
"""EVT files are Windows Event Log files written by older Windows
operating systems (2000, XP, 2003). They are used as binary log
files by several major Windows subsystems and
applications. Typically, several of them can be found in
`%WINDIR%\system32\config` directory:
* Application = `AppEvent.evt`
* System = `SysEvent.evt`
* Security = `SecEvent.evt`
Alternatively, one can export any system event log as distinct .evt
file using relevant option in Event Viewer application.
A Windows application can submit an entry into these logs using
[ReportEventA](https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-reporteventa)
function of Windows API.
Internally, EVT files consist of a fixed-size header and event
records. There are several usage scenarios (non-wrapping vs wrapping
log files) which result in slightly different organization of
records.
.. seealso::
Source - https://learn.microsoft.com/en-us/windows/win32/eventlog/event-log-file-format
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.header = WindowsEvtLog.Header(self._io, self, self._root)
self.records = []
i = 0
while not self._io.is_eof():
self.records.append(WindowsEvtLog.Record(self._io, self, self._root))
i += 1
class Header(KaitaiStruct):
"""
.. seealso::
Source - https://learn.microsoft.com/en-us/previous-versions/windows/desktop/legacy/bb309024(v=vs.85)
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.len_header = self._io.read_u4le()
self.magic = self._io.read_bytes(4)
if not self.magic == b"\x4C\x66\x4C\x65":
raise kaitaistruct.ValidationNotEqualError(b"\x4C\x66\x4C\x65", self.magic, self._io, u"/types/header/seq/1")
self.version_major = self._io.read_u4le()
self.version_minor = self._io.read_u4le()
self.ofs_start = self._io.read_u4le()
self.ofs_end = self._io.read_u4le()
self.cur_rec_idx = self._io.read_u4le()
self.oldest_rec_idx = self._io.read_u4le()
self.len_file_max = self._io.read_u4le()
self.flags = WindowsEvtLog.Header.Flags(self._io, self, self._root)
self.retention = self._io.read_u4le()
self.len_header_2 = self._io.read_u4le()
class Flags(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.reserved = self._io.read_bits_int_be(28)
self.archive = self._io.read_bits_int_be(1) != 0
self.log_full = self._io.read_bits_int_be(1) != 0
self.wrap = self._io.read_bits_int_be(1) != 0
self.dirty = self._io.read_bits_int_be(1) != 0
class Record(KaitaiStruct):
"""
.. seealso::
Source - https://learn.microsoft.com/en-us/windows/win32/api/winnt/ns-winnt-eventlogrecord
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.len_record = self._io.read_u4le()
self.type = self._io.read_u4le()
_on = self.type
if _on == 1699505740:
self._raw_body = self._io.read_bytes((self.len_record - 12))
_io__raw_body = KaitaiStream(BytesIO(self._raw_body))
self.body = WindowsEvtLog.RecordBody(_io__raw_body, self, self._root)
elif _on == 286331153:
self._raw_body = self._io.read_bytes((self.len_record - 12))
_io__raw_body = KaitaiStream(BytesIO(self._raw_body))
self.body = WindowsEvtLog.CursorRecordBody(_io__raw_body, self, self._root)
else:
self.body = self._io.read_bytes((self.len_record - 12))
self.len_record2 = self._io.read_u4le()
class RecordBody(KaitaiStruct):
"""
.. seealso::
Source - https://learn.microsoft.com/en-us/windows/win32/api/winnt/ns-winnt-eventlogrecord
"""
class EventTypes(Enum):
error = 1
audit_failure = 2
audit_success = 3
info = 4
warning = 5
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.idx = self._io.read_u4le()
self.time_generated = self._io.read_u4le()
self.time_written = self._io.read_u4le()
self.event_id = self._io.read_u4le()
self.event_type = KaitaiStream.resolve_enum(WindowsEvtLog.RecordBody.EventTypes, self._io.read_u2le())
self.num_strings = self._io.read_u2le()
self.event_category = self._io.read_u2le()
self.reserved = self._io.read_bytes(6)
self.ofs_strings = self._io.read_u4le()
self.len_user_sid = self._io.read_u4le()
self.ofs_user_sid = self._io.read_u4le()
self.len_data = self._io.read_u4le()
self.ofs_data = self._io.read_u4le()
@property
def user_sid(self):
if hasattr(self, '_m_user_sid'):
return self._m_user_sid
_pos = self._io.pos()
self._io.seek((self.ofs_user_sid - 8))
self._m_user_sid = self._io.read_bytes(self.len_user_sid)
self._io.seek(_pos)
return getattr(self, '_m_user_sid', None)
@property
def data(self):
if hasattr(self, '_m_data'):
return self._m_data
_pos = self._io.pos()
self._io.seek((self.ofs_data - 8))
self._m_data = self._io.read_bytes(self.len_data)
self._io.seek(_pos)
return getattr(self, '_m_data', None)
class CursorRecordBody(KaitaiStruct):
"""
.. seealso::
Source - https://forensics.wiki/windows_event_log_(evt)/#cursor-record
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.magic = self._io.read_bytes(12)
if not self.magic == b"\x22\x22\x22\x22\x33\x33\x33\x33\x44\x44\x44\x44":
raise kaitaistruct.ValidationNotEqualError(b"\x22\x22\x22\x22\x33\x33\x33\x33\x44\x44\x44\x44", self.magic, self._io, u"/types/cursor_record_body/seq/0")
self.ofs_first_record = self._io.read_u4le()
self.ofs_next_record = self._io.read_u4le()
self.idx_next_record = self._io.read_u4le()
self.idx_first_record = self._io.read_u4le()