背景
由于近期网站遭受恶意攻击, 通过对于登录接口的审计与分析, 现已确定了一批可疑账号。既然之前写过一个登录接口的审计脚本, 那么完全可以通过扩展这个脚本来实现对于可疑账号的比对。主要思路: 通过将可疑账存进Redis中, 再利用Lua脚本调用Redis接口进行账号的比对。
先说一下Suricata默认是存在黑名单机制的, 如下:
# IP Reputation
#reputation-categories-file: /etc/suricata/iprep/categories.txt
#default-reputation-path: /etc/suricata/iprep
#reputation-files:
# - reputation.list在Suricata 5.0版本中更是增加了新的功能Datasets。大概看了一下, 可以通过在规则中使用dataset和datarep关键字将大量数据与sticky buffer进行匹配。确实是个很赞的功能!
alert http any any -> any any (http.user_agent; dataset:set, ua-seen, type string, save ua-seen.lst; sid:1;)
alert dns any any -> any any (dns.query; to_sha256; dataset:set, dns-sha256-seen, type sha256, save dns-sha256-seen.lst; sid:2;)
alert http any any -> any any (http.uri; to_md5; dataset:isset, http-uri-md5-seen, type md5, load http-uri-md5-seen.lst; sid:3;)但是… 这并不适用我现在的场景。因为在我的场景中, 用户的登录请求存在于POST Body中, 默认的Suricata方法并不能准确定位到我们需要的账号。这个时候我们就只能依赖于Lua脚本来扩展。当然这些需求Zeek也可以满足, 只是…Zeek的脚本真是难写…主要是我技术太low~
准备阶段
运行环境
OS:Ubuntu 18.04
Suricata: Suricata 5.0.0 RELEASE (我是AWS的流量镜像, 必须使用4.1.5或者5.0版本, 因为要解析VXLAN)
LuaRocks
1.由于Ubuntu默认没有安装LuaRocks(LuaRocks is the package manager for Lua modules), 这里需要我们手动安装。
# 通过apt直接安装, 简单省事儿。
$ apt-get install luarocks
2. 通过luarocks安装我们所需要的lua模块, 这里我们需要用到redis-lua、luasocket这两个模块。
# Install Modules
$ luarocks install luasocket
$ luarocks install redis-lua
$ ll /usr/local/share/lua/5.1/
total 72
drwxr-xr-x 3 root root 4096 Oct 25 03:35 ./
drwxr-xr-x 3 root root 4096 Sep 17 14:14 ../
-rw-r--r-- 1 root root 8331 Oct 25 03:34 ltn12.lua
-rw-r--r-- 1 root root 2487 Oct 25 03:34 mime.lua
-rw-r--r-- 1 root root 35599 Oct 25 03:35 redis.lua
drwxr-xr-x 2 root root 4096 Oct 25 03:34 socket/
-rw-r--r-- 1 root root 4451 Oct 25 03:34 socket.lua
3. 安装成功后, 可以简单的测试一下。
3.1 利用Docker启动Redis容器
$ docker run -ti -d -p 6379:6379 redis
3.2 测试脚本 hello_redis.lua
local redis = require "redis"
local client = redis.connect("127.0.0.1", 6379)
local response = client:ping()
if response == false then
return 0
end
client:set("hello", "world")
local var = client:get("hello")
print(var)
3.3 可能会存在环境变量不对导致的报错
$ luajit hello_redis.lua
luajit: /usr/local/share/lua/5.1/redis.lua:793: module 'socket' not found:
no field package.preload['socket']
no file './socket.lua'
no file '/usr/local/share/luajit-2.0.5/socket.lua'
no file '/usr/local/share/lua/5.1/socket.lua'
no file '/usr/local/share/lua/5.1/socket/init.lua'
no file './socket.so'
no file '/usr/local/lib/lua/5.1/socket.so'
no file '/usr/local/lib/lua/5.1/loadall.so'
stack traceback:
[C]: in function 'require'
/usr/local/share/lua/5.1/redis.lua:793: in function 'create_connection'
/usr/local/share/lua/5.1/redis.lua:836: in function 'connect'
a.lua:3: in main chunk
[C]: at 0x56508049e440
3.4 执行luarocks path –bin 并将结果输入
$ luarocks path --bin
Warning: The directory '/home/canon/.cache/luarocks' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing /usr/local/bin/luarocks with sudo, you may want sudo's -H flag.
export LUA_PATH='/home/canon/.luarocks/share/lua/5.1/?.lua;/home/canon/.luarocks/share/lua/5.1/?/init.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua;./?.lua;/usr/local/share/luajit-2.0.5/?.lua'
export LUA_CPATH='/home/canon/.luarocks/lib/lua/5.1/?.so;/usr/local/lib/lua/5.1/?.so;./?.so;/usr/local/lib/lua/5.1/loadall.so'
export PATH='/home/canon/.luarocks/bin:/usr/local/bin:/home/canon/anaconda3/bin:/home/canon/anaconda3/condabin:/usr/local/sbin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin'
3.5 执行脚本, 将会看到如下输出
$ luajit hello_redis.lua
world
CJson
这里建议大家使用CJson模块, 我之前为了测试随便从github上找了个json模块来使用。这几天发现在网站的高峰时期 Suricataapp_layer.flow这个字段非常的大, 从而导致了kernel_drops。由于我们的网站是面对海外用户想定位问题又存在时差, 经过几天的熬夜最终定位到是由于json模块太过于消耗性能而导致。可以看下这个截图:
a.Suricata监控图 -启用CJson模块之前
b.Suricata监控图 -启用CJson模块之后
1.下载 CJson
# wget 下载
$ wget https://www.kyne.com.au/~mark/software/download/lua-cjson-2.1.0.tar.gz
# Git Clone
$ git clone [email protected]:mpx/lua-cjson.git
2. 根据Lua环境修改Makefile(个人配置)
##### Build defaults #####
LUA_VERSION = 5.1
TARGET = cjson.so
PREFIX = /usr/local
#CFLAGS = -g -Wall -pedantic -fno-inline
CFLAGS = -O3 -Wall -pedantic -DNDEBUG
CJSON_CFLAGS = -fpic
CJSON_LDFLAGS = -shared
LUA_INCLUDE_DIR = $(PREFIX)/include/luajit-2.0
LUA_CMODULE_DIR = $(PREFIX)/lib/lua/$(LUA_VERSION)
LUA_MODULE_DIR = $(PREFIX)/share/lua/$(LUA_VERSION)
LUA_BIN_DIR = $(PREFIX)/bin
3. 安装 CJson
$ make && make install登录接口代码示例
json = require "cjson.safe"
md5 = require "md5"
redis = require "redis"
-- 登录接口
login_url = "/login" -- 根据实际接口而定
-- 登录错误提示
success_code = 0
-- event_name
event_name = "login_audit"
-- event_type
event_type = "lua"
-- logs
name = "login_audit.json"
-- 协议
proto = "TCP"
-- redis_config
host = "127.0.0.1"
port = 6379
-- common_mapping 通用请求头
http_common_mapping = '{"accept":"accept","accept-charset":"accept_charset","accept-encoding":"accept_encoding","accept-language":"accept_language","user-agent":"user_agent"}'
common_mapping_table = json.decode(http_common_mapping)
-- request_mapping 自定义请求头
http_request_mapping = '{"content-length":"request_content_length","content-type":"request_content_type"}'
request_mapping_table = json.decode(http_request_mapping)
-- response_mapping 自定义响应头
http_response_mapping = '{"content-length":"response_content_length","content-type":"response_content_type"}')
-- custom defind functioin
function md5Encode(args)
m = md5.new()
m:update(args)
return md5.tohex(m:finish())
end
function formatBody(args)
t = {}
ios = string.match(args, 'canon')
if ios ~= nil then
mail = 'email"%s+(.-)%s'
t['email'] = string.match(args, mail)
else
data = string.split(args, '&')
for n, v in ipairs(data) do
d = string.split(v, '=')
t[d[1]] = d[2]
end
end
return t
end
function string.split(s, p)
rt = {}
string.gsub(s, '[^'..p..']+', function(w) table.insert(rt, w) end )
return rt
end
-- default function
function init (args)
local needs = {}
needs["protocol"] = "http"
return needs
end
function setup (args)
filename = SCLogPath() .. "/" .. name
file = assert(io.open(filename, "a"))
SCLogInfo("app_login_audit filename: " .. filename)
http = 0
-- Connect Redis Server 连接Redis服务器
SCLogInfo("Connect Redis Server...")
client = redis.connect(host, port)
response = client:ping()
if response then
SCLogInfo("Redis Server connection succeeded.")
end
end
function log(args)
-- init tables
http_table = {}
-- ti tables
ti = {
tags = {}
}
-- init score 初始分数(为后期规则判断而准备, 符合规则进行加分。)
score = 50
-- http_hostname & http_url
http_hostname = HttpGetRequestHost()
http_url = HttpGetRequestUriNormalized()
-- http_method
rl = HttpGetRequestLine()
if rl then
http_method = string.match(rl, "%w+")
if http_method then
http_table["method"] = http_method
end
end
-- 为了保证 Suricata 的性能不受影响, 指定登录接口以及请求才能进入此逻辑。
if http_url == login_url and http_method == "POST" then
http_table["hostname"] = http_hostname
http_table["url"] = http_url
http_table["url_path"] = http_url
-- http_status & http_protocol
rsl = HttpGetResponseLine()
if rsl then
status_code = string.match(rsl, "%s(%d+)%s")
http_table["status"] = tonumber(status_code)
http_protocol = string.match(rsl, "(.-)%s")
http_table["protocol"] = http_protocol
end
-- login_results
a, o, e = HttpGetResponseBody()
if a then
for n, v in ipairs(a) do
body = json.decode(v)
results_code = tonumber(body["code"])
if results_code == success_code then
http_table["results"] = "success"
else
http_table["results"] = "failed"
end
end
http_table["results_code"] = results_code
end
--[[
1. 获取用户登录email并查询Redis中是否存在该账号
2. 根据结果进行相应的打分以及tags标注
--]]
a, o, e = HttpGetRequestBody()
if a then
for n, v in ipairs(a) do
res = formatStr(v)
if res["email"] then
-- 查询Redis对比黑名单
black_ioc = client:get(res["email"])
if black_ioc then
ti["provider"] = "Canon"
ti["producer"] = "NTA"
table.insert(ti["tags"], "account in blacklist")
score = score + 10
end
end
end
end
-- RequestHeaders 根据自定义的请求头进行获取, 对于业务安全来说有些请求头还是有必要获取的。
rh = HttpGetRequestHeaders()
if rh then
for k, v in pairs(rh) do
key = string.lower(k)
common_var = common_mapping_table[key]
if common_var then
http_table[common_var] = v
end
request_var = request_mapping_table[key]
if request_var then
http_table[request_var] = v
end
end
end
-- ResponseHeaders 自定义获取响应头
rsh = HttpGetResponseHeaders()
if rsh then
for k, v in pairs(rsh) do
key = string.lower(k)
common_var = common_mapping_table[key]
if common_var then
http_table[common_var] = v
end
response_var = response_mapping_table[key]
if response_var then
http_table[response_var] = v
end
end
end
-- timestring
sec, usec = SCPacketTimestamp()
timestring = os.date("!%Y-%m-%dT%T", sec) .. '.' .. usec .. '+0000'
-- flow_info
ip_version, src_ip, dst_ip, protocol, src_port, dst_port = SCFlowTuple()
-- flow_id
id = SCFlowId()
flow_id = string.format("%.0f", id)
flow_id = tonumber(flow_id)
-- alerts 查询这笔flow是否存在特征匹配后的告警
has_alerts = SCFlowHasAlerts()
-- true_ip
true_client_ip = HttpGetRequestHeader("True-Client-IP")
if true_client_ip ~= nil then
src_ip = true_client_ip
end
-- session_id
tetrad = src_ip .. src_port .. dst_ip .. dst_port
session_id = md5Encode(tetrad)
-- table
raw_data = {
timestamp = timestring,
flow_id = flow_id,
session_id = session_id,
src_ip = src_ip,
src_port = src_port,
proto = proto,
dest_ip = dst_ip,
dest_port = dst_port,
event_name = event_name,
event_type = event_type,
app_type = app_type,
http = http_table,
alerted = has_alerts,
ti = ti,
score = score
}
-- json encode
data = json.encode(raw_data)
file:write(data .. "\n")
file:flush()
http = http + 1
end
end
function deinit (args)
SCLogInfo ("app_login_audit transactions logged: " .. http);
file:close(file)
end1. 简单说下以上脚本的功能:
a.登录接口的用户名审计(废话…);
b.通过请求Redis比对当前用户是否在黑名单中, 并进行相应的打分、标签处理;
c.根据自定义的需求获取的http headers, 个人觉得这个对于业务安全上还是有点用的;
d. 新增字段”session_id”, 主要考虑是针对CDN或者Nginx这种方向代理的场景下, 可以直接对 xff 或者 true_client_ip 进行四元组的hash, 得到session_id, 这样溯源的时候会比较方便。因为在这种场景下传统的四层flow_id就不是那么有用了。
e.后续可以追加一些简单的检测方法, 例如: (这些适用于我们, 其他的请头脑风暴)
检查请求头中的字段是否完整;
检查请求头中的某个字段长度是否符合合规;
头脑风暴…
2. 配置Suricata启用Lua脚本
- lua:
enabled: yes
scripts-dir: /etc/suricata/lua-output/
scripts:
- login_audit.lua3. 启动Suricata
$ suricata -vvv --pfring -k none -c /etc/suricata/suricata.yaml
注: 这里-vvv 参数建议加上. 如果你的Lua脚本有一些问题, 如果加上了这个参数, 就可以通过这个日志看出。
$ tailf /data/logs/suricata/suricata.log
4/11/2019 -- 02:22:25 - <Warning> - [ERRCODE: SC_ERR_PF_RING_VLAN(304)] - no VLAN header in the raw packet. See #2355.
4/11/2019 -- 02:22:25 - <Warning> - [ERRCODE: SC_ERR_PF_RING_VLAN(304)] - no VLAN header in the raw packet. See #2355.
4/11/2019 -- 02:22:25 - <Warning> - [ERRCODE: SC_ERR_PF_RING_VLAN(304)] - no VLAN header in the raw packet. See #2355.
4/11/2019 -- 02:22:25 - <Warning> - [ERRCODE: SC_ERR_PF_RING_VLAN(304)] - no VLAN header in the raw packet. See #2355.
4/11/2019 -- 02:22:25 - <Warning> - [ERRCODE: SC_ERR_PF_RING_VLAN(304)] - no VLAN header in the raw packet. See #2355.
4/11/2019 -- 02:28:03 - <Info> - failed to run script: /usr/local/share/luajit-2.0.5/md5.lua:347: attempt to get length of local 's' (a nil value)
输出日志样例
{
"src_port": 62722,
"score": 60,
"session_id": "c863aeb2ef8d1b37f3257f8c210bf440",
"ti": {
"tags": [
"account in blacklist"
],
"provider": "Canon",
"producer": "NTA"
},
"alert": {
"alerted": true,
"rules": {
"请求头校验": "dev-id"
}
},
"proto": "TCP",
"flow_id": "1064295903559076",
"timestamp": "2019-10-25T08:33:55.585519+0000",
"event_type": "lua",
"src_ip": "1.1.1.1",
"dest_port": 80,
"http": {
"response_content_length": "96",
"response_content_type": "application/json; charset=UTF-8",
"accept_encoding": "gzip",
"accept": "application/json",
"results_code": 400504,
"server": "nginx",
"date": "Fri, 25 Oct 2019 08:33:55 GMT",
"app_version": "6.6.0",
"request_content_type": "application/x-www-form-urlencoded",
"user_agent": "okhttp/3.12.0",
"url": "/login",
"email": "[email protected]",
"results": "failed",
"pragma": "no-cache",-
"cache_control": "no-cache, max-age=0, no-store",
"connection": "keep-alive",
"status": 200,
"protocol": "HTTP/1.1",
"hostname": "x.x.x.x",
"url_path": "/login",
"method": "POST",
"device": "RMX1920 Android8.0.0",
"device_type": "Android",
"request_content_length": "39"
},
"event_name": "login_audit",
"dest_ip": "2.2.2.2"
}
*本文作者：Shell.，转载请注明来自FreeBuf.COM
来源：freebuf.com 2019-11-20 09:00:12 by: Shell.
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