87. Snare
The Snare Agent is a popular log collection software for Windows EventLog. The Snare format is supported by many tools and SIEM vendors. It uses tab delimited records and can use Syslog as the transport. NXLog can be configured to collect or forward logs in the Snare format.
The Snare format can be used with or without the Syslog header.
HOSTNAME⇥MSWinEventLog⇥Criticality⇥EventLogSource⇥SnareCounter⇥SubmitTime⇥EventID⇥SourceName⇥UserName⇥SIDType⇥EventLogType⇥ComputerName⇥CategoryString⇥DataString⇥ExpandedString⇥OptionalMD5Checksum<PRI>TIMESTAMP HOSTNAME MSWinEventLog⇥Criticality⇥EventLogSource⇥SnareCounter⇥SubmitTime⇥EventID⇥SourceName⇥UserName⇥SIDType⇥EventLogType⇥ComputerName⇥CategoryString⇥DataString⇥ExpandedString⇥OptionalMD5Checksum87.1. Collecting Snare
NXLog can parse Snare logs with the parse_csv() procedure provided by the xm_csv extension module.
With the following configuration, NXLog will accept Snare format logs via UDP, parse them, convert to JSON, and output the result to file. This configuration supports both "Snare over Syslog" and the regular Snare format.
![[Download file]](images/icons/download_icon.png "Download file"){kind=icon}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
<Extension snare>
Module xm_csv
Fields $MSWINEventLog, $Criticality, $EventLogSource, $SnareCounter, \
$SubmitTime, $EventID, $SourceName, $UserName, $SIDType, \
$EventLogType, $ComputerName, $Category, $Data, $Expanded, \
$MD5Checksum
FieldTypes string, integer, string, integer, datetime, integer, string, \
string, string, string, string, string, string, string, string
Delimiter \t
</Extension>
<Extension json>
Module xm_json
</Extension>
<Extension syslog>
Module xm_syslog
</Extension>
<Input in>
Module im_udp
Host 0.0.0.0
Port 6161
<Exec>
parse_syslog_bsd();
if $Message =~ /^((\w+)\t)?(MSWinEventLog.+)$/
{
if $2 != ''
{
$Hostname = $2;
$Message = $3;
}
snare->parse_csv($Message);
$Message = $Expanded;
}
</Exec>
</Input>
<Output out>
Module om_file
File '/var/log/json'
Exec to_json();
</Output>
<Route r>
Path in => out
</Route>
<13>Nov 21 11:40:27 myserver MSWinEventLog⇥0⇥Security⇥32⇥Mon Nov 21 11:40:27 2016⇥592⇥Security⇥Andy⇥User⇥Success Audit⇥MAIN⇥DetailedTracking⇥Process ended⇥Ended process ID: 2455{
"EventReceivedTime": "2016-11-21 11:40:28",
"SourceModuleName": "in",
"SourceModuleType": "im_file",
"SyslogFacilityValue": 1,
"SyslogFacility": "USER",
"SyslogSeverityValue": 5,
"SyslogSeverity": "NOTICE",
"SeverityValue": 2,
"Severity": "INFO",
"Hostname": "myserver",
"EventTime": "2016-11-21 11:40:27",
"Message": "Ended process ID: 2455",
"MSWINEventLog": "MSWinEventLog",
"Criticality": 0,
"EventLogSource": "Security",
"SnareCounter": 32,
"SubmitTime": "2016-11-21 11:40:27",
"EventID": 592,
"SourceName": "Security",
"UserName": "Andy",
"SIDType": "User",
"EventLogType": "SuccessAudit",
"ComputerName": "MAIN",
"CategoryString": "DetailedTracking",
"DataString": "Process ended",
"ExpandedString": "Ended process ID: 2455"
}87.2. Generating Snare
NXLog can also generate Snare logs in place of the original Snare agent with the to_syslog_snare() procedure provided by the xm_syslog extension module.
With this configuration, NXLog will read the Windows EventLog, convert it to Snare format, and output it via UDP. NXLog log messages are also included (via the im_internal module). Tabs and newline sequences are replaced with spaces.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
<Extension syslog>
Module xm_syslog
</Extension>
<Input internal>
Module im_internal
</Input>
<Input eventlog>
Module im_msvistalog
Exec $Message =~ s/(\t|\R)/ /g;
</Input>
<Output out>
Module om_udp
Host 192.168.1.1
Port 514
Exec to_syslog_snare();
</Output>
<Route r>
Path internal, eventlog => out
</Route>
<13>Nov 21 11:40:27 myserver MSWinEventLog⇥0⇥Security⇥32⇥Mon Nov 21 11:40:27 2016⇥592⇥Security⇥N/A⇥N/A⇥Success Audit⇥MAIN⇥DetailedTracking⇥Process ended⇥Ended process ID: 2455