initial commit for Netwitness-EPL backend

This commit is contained in:
snake-jump 2020-09-10 17:12:12 +02:00
parent 0603264a09
commit 64035fd799
2 changed files with 247 additions and 0 deletions

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title: NetWitness
order: 20
backends:
- netwitness-epl
logsources:
linux:
product: linux
conditions:
device.class: rhlinux
linux-sshd:
product: linux
service: sshd
conditions:
device.class: rhlinux
client: sshd
linux-auth:
product: linux
service: auth
conditions:
device.class: rhlinux
linux-clamav:
product: linux
service: clamav
conditions:
device.class: rhlinux
windows-sys:
product: windows
service: sysmon
conditions:
device.type: winevent_nic
event.source: microsoft-windows-security-auditing
windows-power:
product: windows
service: powershell
conditions:
device.type: winevent_nic
windows-dhcp:
product: windows
service: dhcp
conditions:
device.type: winevent_nic
event.source: microsoft-windows-dhcp-server
windows-sec:
product: windows
service: security
conditions:
device.type: winevent_nic
event.source: microsoft-windows-security-auditing
windows-system:
product: windows
service: system
conditions:
device.type: winevent_nic
fieldmappings:
dst:
- ip.dst
dst_ip:
- ip.dst
src:
- ip.src
src_ip:
- ip.src
DestinationPort:
- ip.dstport
EventID:
- reference.id
NewProcessName:
- process
LogonType:
- logon.type
AccountName:
- user.dst
c-uri-extension:
- extension
c-useragent:
- user.agent
r-dns:
- alias.host
DestinationHostname:
- alias.host
cs-host:
- alias.host
c-uri-query:
- web.page
c-uri:
- web.page
cs-method:
- action
cs-cookie:
- web.cookie
SubjectUserName:
- user.dst

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# NetWitness EPL output backend for sigmac
# Copyright 2019 Tarik BOUDJEMAA (@snake-jump)
# Inspired from John Tuckner (@tuckner) NetWitness output backend for sigmac
# NetWitness EPL backend for sigmac uses netwitness-epl.yml config file
# RSA Alerts are generated by Event Processing Language (EPL) , that uses Esper Engine (https://www.espertech.com/esper/)
# For more details see :https://community.rsa.com/docs/DOC-110246 and https://community.rsa.com/docs/DOC-80068
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import re
import sigma
from .base import SingleTextQueryBackend
from .mixins import MultiRuleOutputMixin
import sqlparse
template="""
module_XXXXX;
@Name('RuleName')
@RSAAlert(oneInSeconds=0)
SELECT * FROM Event(
EXPRESSION
);"""
class NetWitnessEplBackend(SingleTextQueryBackend):
"""Converts Sigma rule into RSA NetWitness EPL . Contributed by @snake-jump"""
identifier = "netwitness-epl"
config_required = False
default_config = ["netwitness-epl"]
active = True
reEscape = re.compile('(")')
##reEscape = re.compile("([\\|()\[\]{}.^$+])")
reClear = None
andToken = " AND "
orToken = " OR "
notToken = "NOT"
subExpression = "(%s)"
listExpression = "(%s)"
listSeparator = ", "
valueExpression = "\'%s\'"
keyExpression = "%s"
nullExpression = "%s exists"
notNullExpression = "%s exists"
mapExpression = "(%s=%s)"
mapListsSpecialHandling = True
def generateMapItemNode(self, node):
key, value = node
if type(key) != int:
key = key.replace(".","_") ## replace . by _ in meta name (RSA EPL)
key = key.lower()
if self.mapListsSpecialHandling == False and type(value) in (str, int, list) or self.mapListsSpecialHandling == True and type(value) in (str, int):
if type(value) == str and "*" in value[1:-1]:
value = re.sub('([".^$]|\\\\(?![*?]))', '\\\\\g<1>', value)
value = re.sub('\\*', '.*', value)
value = re.sub('\\?', '.', value)
return "(%s REGEXP %s)" %(key, self.generateValueNode(value))
elif type(value) == str and "*" in value:
value = re.sub("(\*\\\\)|(\*)", "", value)
value = self.generateValueNode("%"+value+"%") # add "%" to construct the like expression ex: process like %psexesvc%
return "(%s LIKE %s)" % (key,value)
elif type(value) in (str, int):
return self.mapExpression % (key, self.generateValueNode(value))
else:
return self.mapExpression % (key, self.generateNode(value))
elif type(value) == list:
return self.generateMapItemListNode(key, value)
elif value is None:
return self.nullExpression % (key, )
else:
raise TypeError("Backend does not support map values of type " + str(type(value)))
def generateMapItemListNode(self, key, value):
equallist = list()
containlist = list()
regexlist = list()
for item in value:
if type(item) == str and "*" in item[1:-1]:
item = re.sub('([".^$]|\\\\(?![*?]))', '\\\\\g<1>', item)
item = re.sub('\\*', '.*', item)
item = re.sub('\\?', '.', item)
regexlist.append(self.generateValueNode(item))
elif type(item) == str and (item.endswith("*") or item.startswith("*")):
item_temp=item
item = re.sub("(\*\\\\)|(\*)", "", item)
if item_temp.endswith("*") and item_temp.startswith("*"): # pattern begins with "*" and ends with "*"
containlist.append(self.generateValueNode('%'+item+'%')) # add "%" to construct the like expression ex: process like %psexesvc%
elif item_temp.startswith("*"): # pattern don't end with "*"
containlist.append(self.generateValueNode('%'+item))
else: # item_temp.endswith("*") pattern don't begin with "*"
containlist.append(self.generateValueNode(item+'%'))
else:
equallist.append(self.generateValueNode(item))
fmtitems = list()
if equallist:
if len(equallist) == 1:
fmtitems.append("%s = %s" % (key, ", ".join(equallist)))
else:
# add "(" and ")" to the first and the last item from the list to have meta_key IN ('value1','value2')
equallist[0]=("("+equallist[0])
equallist[-1]=(equallist[-1]+")")
fmtitems.append("%s IN %s" % (key, ", ".join(equallist)))
if containlist:
fmtitems.append("%s LIKE %s" % (key, (" OR "+key+" LIKE ").join(containlist)))
if regexlist:
fmtitems.append("%s REGEXP %s" % (key, "|".join(regexlist)))
fmtquery = "("+" OR ".join(filter(None, fmtitems))
# delete the " ' " from the begin or the end of the each regex pattern ex : '.*('patern1'|'patern2').*' --> '.*(patern1|patern2).*'
fmtquery = re.sub('\'\.\*\(\'','\'.*(',fmtquery)
fmtquery = re.sub('\'\)\.\*\'',').*\'',fmtquery)
fmtquery = re.sub('\'\|\'','|',fmtquery)
fmtquery = fmtquery+')'
return fmtquery
def generateValueNode(self, node):
return self.valueExpression % (str(node))
def generate(self, sigmaparser):
"""Method is called for each sigma rule and receives the parsed rule (SigmaParser)"""
for k in sigmaparser.parsedyaml["detection"].keys():
if k.startswith('keyword'):
raise NotImplementedError("Backend does not support keywords")
for parsed in sigmaparser.condparsed:
query = self.generateQuery(parsed, sigmaparser)
query = sqlparse.format(query, reindent=True, keyword_case='upper')
query=query.replace('INDEX','`index`') # index is reserved keyword in Esper and must be escaped
query=template.replace('EXPRESSION', query)
try:
query=query.replace('RuleName', sigmaparser.parsedyaml["title"].replace(" ","")) # add rule name
query=query.replace('module_XXXXX', "module "+sigmaparser.parsedyaml["title"].replace(" ","")) # add rule name
except:
print("Error when replacing RuleName by Title from yaml")
pass
return query
def generateQuery(self, parsed, sigmaparser):
result = self.generateNode(parsed.parsedSearch)
return result