一、ELK安裝
1.2 elk配置
logstash自定義配置文件，取名為filebeat_log.conf ：
input {
beats {
port => 5044
client_inactivity_timeout => 90
codec => json
}
}
filter {
date {
match => [ "timestamp", "dd/MMM/yyyy:HH:mm:ss Z" ]
target => ["datetime"]
}
geoip {
source => "remote_addr"
}
mutate {
remove_field => ["tags", "beat"]
}
}
output {
stdout {
codec => rubydebug
}
elasticsearch {
hosts => "localhost:9200"
index => "logstash-%{+YYYY.MM.dd}"
}
}
1.3 啟動方法
logstash啟動
進入/usr/share/logstash/bin：
nohup ./logstash -f filebeat_log.conf> /dev/null 2>&1 &
二、使用filebeat進行分布式收集
下面以tomcat為例子，分享我的配置文件filebeat.yml（nginx的話，修改paths的路徑）：
filebeat.prospectors:
- type: log
enabled: true
paths:
- /home/qy/apache-tomcat-9.0.1/logs/localhost_access_log.*.txt
document_type: tomcat-log
scan_frequency: 15s
ignore_older: 20m
close_inactive: 12m
clean_inactive: 30m
close_removed: true
clean_removed: true
....
#----------------------------- Logstash output --------------------------------
output.logstash:
hosts: ["188.88.88.88:5044"]
直接解壓下載的tar包，進入目錄修改配置文件。然后啟動filebeat：nohup ./filebeat -e -c filebeat.yml >/dev/null 2>&1 &
三、日志格式轉json
為方便kibana分析和elastalert的取值，日志的格式要為json格式，上述的logstash配置文件已適配json格式。
公司的應用服務器中均為nginx和tomcat，故本文只介紹tomcat及nginx的json格式配置方法，其他服務器配置方法請自行搜索。
3.1 tomcat的json格式配置
打開config/server.xml,在最后的位置修改log的輸出配置為：
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" prefix="localhost_access_log" suffix=".txt" pattern="{"time":"%t","remote_addr":"%h","remote_user":"%l","request":"%r","status":"%s","body_bytes_sent":"%b","http_referer":"%{Referer}i","http_user_agent":"%{User-Agent}i","http_x_forwarded_for":" %{X-Forwarded-For}i","request_time":"%T","host":"%v","port":"%p"}"/>
然后重啟tomcat，即生效。
3.2 nginx的json格式配置
進入`/etc/nginx`打開`nginx.conf`，加入如下配置：
http {
##
# Basic Settings
##
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
# server_tokens off;
log_format logstash_json '{"time": "$time_local", '
'"remote_addr": "$remote_addr", '
'"remote_user": "$remote_user", '
'"request": "$request", '
'"status": "$status", '
'"body_bytes_sent": "$body_bytes_sent", '
'"http_referer": "$http_referer", '
'"http_user_agent": "$http_user_agent", '
'"http_x_forwarded_for": "$http_x_forwarded_for", '
'"request_time": "$request_time", '
'"request_length": "$request_length", '
'"host": "$http_host"}';
}
最后nginx -s reload即可
四、使用elastalert進行告警
ElastAlert使用python編寫，具有容易上手、文檔全等特點，雖然這個工具擁有如此多的優點，在搭建過程還是遇到了很多很多的未知錯誤，主要原因是網上的資料大多是針對es5.x以前的版本而沒什么現成的資料可供參考。
4.1 安裝elastalert
git clone https://github.com/Yelp/elastalert.git
cd elastalert
python setup.py install //可能需要sudo
Pip install -r requirements.txt //可能需要sudo
cp config.yaml.example config.yaml
具體的功能本文就不一一介紹了，請自行前往官方文檔了解
4.2 創建索引
安裝完成后會系統中會自帶三個命令：
elastalert-create-index、elastalert-rule-from-kibana 、elastalert-test-rule
使用elastalert-create-index，根據提示設置es后按回車默認即可。
配置完索引及配置文件后，可以使用elastalert-test-rule進行測試。這里有個bug，如果出現TransportError(400, u'search_phase_execution_exception', u'No mapping found for [alert_time] in order to sort on')之類的錯誤，在確認沒有其他的問題時，可以先刪除索引curl -XDELETE http://localhost:9200/*,再使用elastalert-create-index重新生成索引。
4.3 配置config.yaml
rules_folder: example_rules
# How often ElastAlert will query Elasticsearch
# The unit can be anything from weeks to seconds
run_every:
seconds: 3 #每三秒向es請求數據
# ElastAlert will buffer results from the most recent
# period of time, in case some log sources are not in real time
buffer_time:
minutes: 15
#日志會延遲進入es，這里是配置query的向前的時間范圍，這是15分鍾，即查詢 time[now-15m, now]
# The Elasticsearch hostname for metadata writeback
# Note that every rule can have its own Elasticsearch host
es_host: 188.88.88.88
# The Elasticsearch port
es_port: 9200
# Optional URL prefix for Elasticsearch
#es_url_prefix: elasticsearch
# Connect with TLS to Elasticsearch
#use_ssl: True
# Verify TLS certificates
#verify_certs: True
# GET request with body is the default option for Elasticsearch.
# If it fails for some reason, you can pass 'GET', 'POST' or 'source'.
# See http://elasticsearch-py.readthedocs.io/en/master/connection.html?highlight=send_get_body_as#transport
# for details
#es_send_get_body_as: GET
# Option basic-auth username and password for Elasticsearch
#es_username: someusername
#es_password: somepassword
# The index on es_host which is used for metadata storage
# This can be a unmapped index, but it is recommended that you run
# elastalert-create-index to set a mapping
writeback_index: elastalert_status
# If an alert fails for some reason, ElastAlert will retry
# sending the alert until this time period has elapsed
alert_time_limit:
days: 1
以上各字段的解釋：
Rules_folder：用來加載下一階段rule的設置，默認是example_rules
Run_every：用來設置定時向elasticsearch發送請求
Buffer_time：用來設置請求里時間字段的范圍，默認是45分鍾
Es_host：elasticsearch的host地址
Es_port：elasticsearch 對應的端口號
Use_ssl：可選的，選擇是否用SSL連接es，true或者false
Verify_certs：可選的，是否驗證TLS證書，設置為true或者false，默認為- true
Es_username：es認證的username
Es_password：es認證的password
Es_url_prefix：可選的，es的url前綴（我的理解是https或者http）
Es_send_get_body_as：可選的，查詢es的方式，默認的是GET
Writeback_index：elastalert產生的日志在elasticsearch中的創建的索引
Alert_time_limit：失敗重試的時間限制
4.4 告警配置介紹
在example_rules目錄中新建yaml配置文件 webattack_frequency.yaml,下面分開介紹這個配置文件的內容（下個小節將分享我的配置文件，此小節僅解釋其中的必要設置項）：
1、告警規則
ElastAlert支持11種告警規則，本文不一一介紹了，為響應web攻擊行為，本文選用的告警規則是frequency。
name: web attack
# (Required)
# Type of alert.
# the frequency rule type alerts when num_events events occur with timeframe time
type: frequency
# (Required, frequency specific)
# Alert when this many documents matching the query occur within a timeframe
num_events: 10
# (Required, frequency specific)
# num_events must occur within this amount of time to trigger an alert
timeframe:
minutes: 1
# (Required)
# Index to search, wildcard supported
index: logstash-* #對應logstash的配置文件中output的elasticsearch index前綴
filter:
- query_string:
# sql insert xss detect
query: "request: select.+(from|limit) OR request: union(.*?)select OR request: into.+(dump|out)file "
上述配置文件的意圖即是：在一分鍾內將匹配query里面的sql注入規則，若匹配次數達到10次，即進行報警。
2、使用郵箱進行告警
ElastAlert提供了 10 多種通知的類型，本文選用的是郵箱告警，還有微信告警、釘釘告警，若有需要，請自行配置。
smtp_host: smtp.qiye.163.com
smtp_port: 25
smtp_auth_file: /Users/qy/Downloads/work/elastalert/example_rules/smtp_auth_file.yaml
#回復給那個郵箱
email_reply_to: xxx@163.com
#從哪個郵箱發送
from_addr: xxx@163.com
# (Required)
# The alert is use when a match is found
alert:
- "email"
# (required, email specific)
# a list of email addresses to send alerts to
email:
- "shystartree@163.com"
alert_subject: "web attack may be by {} at @{}"
alert_subject_args:
- remote_addr
- time
alert_text_type: alert_text_only
alert_text: |
你好，服務器({})可能正在受到web攻擊，請采取手段阻止！！！！
### 截止發郵件前匹配到的請求數：{}
> 發生時間: {}
> timestamp:{}
> attacker's ip: {}
> request: {}
> status:{}
> UA頭:{}
>>> 參考來源：{}
alert_text_args:
- host
- num_hits
- time
- "@timestamp"
- remote_addr
- request
- status
- http_user_agent
- source
smtp_auth_file.yaml的配置內容會在下個小節給出，在這個配置中，我自定義了 alert 的內容，更為精確地突出了攻擊者ip、受攻擊的服務器、攻擊事件等信息。
3、減少重復告警的頻率
在實際的使用中，若使用上述的配置，受到攻擊的時候郵箱將不斷地收到郵件，而這些郵件都對應着同一個攻擊實例，根本沒必要重復收取，於是，我使用了如下的配置：
# 用來區分報警，跟 realert 配合使用，在這里意味着，
# 5 分鍾內如果有重復報警，那么當 name 不同時，會當做不同的報警處理，可以是數組
query_key:
- name
# 5 分鍾內相同的報警不會重復發送
realert:
minutes: 5
# 指數級擴大 realert 時間，中間如果有報警，
# 則按照 5 -> 10 -> 20 -> 40 -> 60 不斷增大報警時間到制定的最大時間，
# 如果之后報警減少，則會慢慢恢復原始 realert 時間
exponential_realert:
hours: 1
在本人實際測試的攻擊場景中，發現使用了exponential_realert后，會錯過很多告警（這些告警並不是同一個攻擊實例），暫時不確定原因，還請讀者們自行確定是否開啟該設置。
4.5webattack_frequency.yaml及smtp_auth_file.yaml配置文件內容
上述的4.4小節中對每個配置都作了簡單的介紹，這里就直接放出web攻擊預警的配置文件供各位讀者參考。
webattack_frequency.yaml:
# Alert when the rate of events exceeds a threshold
# (Optional)
# Elasticsearch host
#es_host: 188.88.88.88
# (Optional)
# Elasticsearch port
#es_port: 9200
# (OptionaL) Connect with SSL to Elasticsearch
#use_ssl: True
# (Optional) basic-auth username and password for Elasticsearch
#es_username: someusername
#es_password: somepassword
# (Required)
# Rule name, must be unique
name: web attack
realert:
minutes: 5
# (Required)
# Type of alert.
# the frequency rule type alerts when num_events events occur with timeframe time
type: frequency
# (Required)
# Index to search, wildcard supported
index: logstash-*
# (Required, frequency specific)
# Alert when this many documents matching the query occur within a timeframe
num_events: 10
# (Required, frequency specific)
# num_events must occur within this amount of time to trigger an alert
timeframe:
#hours: 4
minutes: 1
# (Required)
# A list of Elasticsearch filters used for find events
# These filters are joined with AND and nested in a filtered query
# For more info: http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl.html
#filter:
#- term:
# some_field: "some_value"
filter:
- query_string:
# sql insert xss detect
query: "request: select.+(from|limit) OR request: union(.*?)select OR request: into.+(dump|out)file OR
request: (base64_decode|sleep|benchmark|and.+1=1|and.+1=2|or%20|exec|information_schema|where%20|union%20|%2ctable_name%20|cmdshell|table_schema) OR
request: (iframe|script|body|img|layer|div|meta|style|base|object|input|onmouseover|onerror|onload) OR
request: .+etc.+passwd OR http_user_agent：(HTTrack|harvest|audit|dirbuster|pangolin|nmap|sqln|-scan|hydra|Parser|libwww|BBBike|sqlmap|w3af|owasp|Nikto|fimap|havij|PycURL|zmeu|BabyKrokodil|netsparker|httperf|bench) OR
status: (400|404|500|501)
NOT (request:_health.html OR remote_addr:222.222.222.222 )
"
smtp_host: smtp.qiye.163.com
smtp_port: 25
smtp_auth_file: /Users/qy/Downloads/work/elastalert/example_rules/smtp_auth_file.yaml
#回復給那個郵箱
email_reply_to: xxx@163.com
#從哪個郵箱發送
from_addr: xxx@163.com
# (Required)
# The alert is use when a match is found
alert:
- "email"
# (required, email specific)
# a list of email addresses to send alerts to
email:
- "shystartree@163.com"
alert_subject: "web attack may be by {} at @{}"
alert_subject_args:
- remote_addr
- time
alert_text_type: alert_text_only
alert_text: |
你好，服務器({})可能正在受到web攻擊，請采取手段阻止！！！！
### 截止發郵件前匹配到的請求數：{}
> 發生時間: {}
> timestamp:{}
> attacker's ip: {}
> request: {}
> status:{}
> UA頭:{}
>>> 參考來源：{}
alert_text_args:
- host
- num_hits
- time
- "@timestamp"
- remote_addr
- request
- status
- http_user_agent
- source
smtp_auth_file.yaml:
user: xxx@163.com
password: password
4.6 運行elastalert
在成功配置完ElastAlert后將生成三個配置文件：
config.yaml、webattack_frequency.yaml、smtp_auth_file.yaml
- 啟動elastalert服務，監聽elasticsearch：
nohup python -m elastalert.elastalert --verbose --rule webattack_frequency.yaml >/dev/null 2>&1 &
- 為實現守護進程的作用，可以配合
supervisor進行使用，本文不再闡述。
4.7 運行效果：
當匹配到自定義攻擊規則的時候，ElastAlert將會以郵件方式發送告警信息：
web attack may be by 104.38.13.21 at @[13/Jan/2018:16:06:58 +0800]
xxx 發給 shystartree
你好，服務器(199.222.36.31)可能正在受到web攻擊，請采取手段阻止！！！！
### 截止發郵件前匹配到的請求數：20
> 發生時間: [13/Jan/2018:16:06:58 +0800]
> timestamp:2018-01-13T08:07:04.930Z
> attacker's ip: 184.233.9.121
> request: GET /dbadmin/scripts/setup.php HTTP/1.0
> status:200
> UA頭:ZmEu
>>> 參考來源：/log/localhost_access_log.2018-01-13.txt