AgentSmith-HIDS : Open Source Host-based Intrusion Detection System

Technically, AgentSmith-HIDS is not a Host-based Intrusion Detection System (HIDS) due to lack of rule engine and detection function. However, it can be used as a high performance ‘Host Information Collect Agent’ as part of your own HIDS solution.

The comprehensiveness of information which can be collected by this agent was one of the most important metrics during developing this project, hence it was built to function in the kernel stack and achieve huge advantage comparing to those function in user stack, such as:

• Better performance, Information needed are collected in kernel stack to avoid additional supplement actions such as traversal of ‘/proc’; and to enhance the performance of data transportation, data collected is transferred via shared ram instead of netlink.
• Hard to be bypassed, Information collection was powered by specifically designed kernel drive, makes it almost impossible to bypass the detection for malicious software like rootkit, which can deliberately hide themselves.
• Easy to be integrated，The AgentSmith-HIDS was built to integrate with other applications and can be used not only as security tool but also a good monitoring tool, or even a good detector of your assets. The agent is capable of collecting the users, files, processes and internet connections for you, so let’s imagine when you integrate it with CMDB, you could get a comprehensive map consists of your network, host, container and business (even dependencies). What if you also have a Database audit tool at hand? The map can be extended to contain the relationship between your DB, DB User, tables, fields, applications, network, host and containers etc. Thinking of the possibility of integration with network intrusion detection system and/or threat intelligence etc., higher traceability could also be achieved. It just never gets old.
• Kernel stack + User stack，AgentSmith-HIDS also provide user stack module, to further extend the functionality when working with kernel stack module.

Also Read – Yarasafe : SAFE Embeddings To Match Functions In Yara

Major abilities of AgentSmith-HIDS：

• Kernel stack module hooks execve, connect, process inject, create file, DNS query, load LKM behaviors via Kprobe，and is also capable of monitoring containers by being compatible with Linux namespace.
• User stack module utilize built in detection functions including queries of User List，Listening ports list，System RPM list，Schedule jobs
• AntiRootkit，From: Tyton ,for now add PROC_FILE_HOOK，SYSCALL_HOOK，LKM_HIDDEN，INTERRUPTS_HOOK feature，but only wark on Kernel > 3.10.
• Cred Change monitoring (sudo/su/sshd except)
• User Login monitoring

About the compatibility with Kernel version

• Kernel > 2.6.25
• AntiRootKit > 3.10

About the compatibility with Containers

Source	Nodename
Host	hostname
Docker	container name
k8s	pod name

Composition of AgentSmith-HIDS

• Kernel stack module (LKM) Hook key functions via Kprobe to capture information needed.
• User stack module Collect data capatured by kernel stack module, perform necessary process and send it to Kafka; Keep sending heartbeat packet to server so process integrity can be identitied; Execute commands received from server.
• Agent Server(Optional) Send commands to user stack module and monitoring the status of user stack module.

Execve Hook

Achieved by hooking sys_execve()/sys_execveat()/compat_sys_execve()/compat_sys_execveat(), example:

{
“uid”:”0″,
“data_type”:”59″,
“run_path”:”/opt/ltp/testcases/bin/growfiles”,
“exe”:”/opt/ltp/testcases/bin/growfiles”,
“argv”:”growfiles -W gf26 -D 0 -b -i 0 -L 60 -u -B 1000b -e 1 -r 128-32768:128 -R 512-64000 -T 4 -f gfsmallio-35861 -d /tmp/ltp-Ujxl8kKsKY “,
“pid”:”35861″,
“ppid”:”35711″,
“pgid”:”35861″,
“tgid”:”35861″,
“comm”:”growfiles”,
“nodename”:”test”,
“stdin”:”/dev/pts/1″,
“stdout”:”/dev/pts/1″,
“sessionid”:”3″,
“dip”:”192.168.165.1″,
“dport”:”61726″,
“sip”:”192.168.165.128″,
“sport”:”22″,
“sa_family”:”1″,
“pid_tree”:”1(systemd)->1384(sshd)->2175(sshd)->2177(bash)->2193(fish)->35552(runltp)->35711(ltp-pan)->35861(growfiles)”,
“tty_name”:”pts1″,
“socket_process_pid”:”2175″,
“socket_process_exe”:”/usr/sbin/sshd”,
“SSH_CONNECTION”:”192.168.165.1 61726 192.168.165.128 22″,
“LD_PRELOAD”:”/root/ldpreload/test.so”,
“user”:”root”,
“time”:”1579575429143″,
“local_ip”:”192.168.165.128″,
“hostname”:”test”,
“exe_md5″:”01272152d4901fd3c2efacab5c0e38e5”,
“socket_process_exe_md5″:”686cd72b4339da33bfb6fe8fb94a301f”
}

Connect Hook

Achieved by hooking sys_connect(), example:

{
“uid”:”0″,
“data_type”:”42″,
“sa_family”:”2″,
“fd”:”4″,
“dport”:”1025″,
“dip”:”180.101.49.11″,
“exe”:”/usr/bin/ping”,
“pid”:”6294″,
“ppid”:”1941″,
“pgid”:”6294″,
“tgid”:”6294″,
“comm”:”ping”,
“nodename”:”test”,
“sip”:”192.168.165.153″,
“sport”:”45524″,
“res”:”0″,
“sessionid”:”1″,
“user”:”root”,
“time”:”1575721921240″,
“local_ip”:”192.168.165.153″,
“hostname”:”test”,
“exe_md5″:”735ae70b4ceb8707acc40bc5a3d06e04”
}

DNS Query Hook

Achieved by hooking sys_recvfrom(), example:

{
“uid”:”0″,
“data_type”:”601″,
“sa_family”:”2″,
“fd”:”4″,
“dport”:”53″,
“dip”:”192.168.165.2″,
“exe”:”/usr/bin/ping”,
“pid”:”6294″,
“ppid”:”1941″,
“pgid”:”6294″,
“tgid”:”6294″,
“comm”:”ping”,
“nodename”:”test”,
“sip”:”192.168.165.153″,
“sport”:”53178″,
“qr”:”1″,
“opcode”:”0″,
“rcode”:”0″,
“query”:”www.baidu.com”,
“sessionid”:”1″,
“user”:”root”,
“time”:”1575721921240″,
“local_ip”:”192.168.165.153″,
“hostname”:”test”,
“exe_md5″:”39c45487a85e26ce5755a893f7e88293”
}

Create File Hook

Achieved by hooking security_inode_create(), example:

{
“uid”:”0″,
“data_type”:”602″,
“exe”:”/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-0.el7_7.x86_64/jre/bin/java”,
“file_path”:”/tmp/kafka-logs/replication-offset-checkpoint.tmp”,
“pid”:”3341″,
“ppid”:”1″,
“pgid”:”2657″,
“tgid”:”2659″,
“comm”:”kafka-scheduler”,
“nodename”:”test”,
“sessionid”:”3″,
“user”:”root”,
“time”:”1575721984257″,
“local_ip”:”192.168.165.153″,
“hostname”:”test”,
“exe_md5″:”215be70a38c3a2e14e09d637c85d5311”,
“create_file_md5″:”d41d8cd98f00b204e9800998ecf8427e”
}

Process Inject Hook

Achieved by hooking sys_ptrace(), example:

{
“uid”:”0″,
“data_type”:”101″,
“ptrace_request”:”4″,
“target_pid”:”7402″,
“addr”:”00007ffe13011ee6″,
“data”:”-a”,
“exe”:”/root/ptrace/ptrace”,
“pid”:”7401″,
“ppid”:”1941″,
“pgid”:”7401″,
“tgid”:”7401″,
“comm”:”ptrace”,
“nodename”:”test”,
“sessionid”:”1″,
“user”:”root”,
“time”:”1575722717065″,
“local_ip”:”192.168.165.153″,
“hostname”:”test”,
“exe_md5″:”863293f9fcf1af7afe5797a4b6b7aa0a”
}

Load LKM File Hook

Achieved by hooking load_module(), example:

{
“uid”:”0″,
“data_type”:”603″,
“exe”:”/usr/bin/kmod”,
“lkm_file”:”/root/ptrace/ptrace”,
“pid”:”29461″,
“ppid”:”9766″,
“pgid”:”29461″,
“tgid”:”29461″,
“comm”:”insmod”,
“nodename”:”test”,
“sessionid”:”13″,
“user”:”root”,
“time”:”1577212873791″,
“local_ip”:”192.168.165.152″,
“hostname”:”test”,
“exe_md5″:”0010433ab9105d666b044779f36d6d1e”,
“load_file_md5″:”863293f9fcf1af7afe5797a4b6b7aa0a”
}

Cred Change Hook

Achieved by Hook commit_creds()，example：

{
“uid”:”0″,
“data_type”:”604″,
“exe”:”/tmp/tt”,
“pid”:”27737″,
“ppid”:”26865″,
“pgid”:”27737″,
“tgid”:”27737″,
“comm”:”tt”,
“old_uid”:”1000″,
“nodename”:”test”,
“sessionid”:”42″,
“user”:”root”,
“time”:”1578396197131″,
“local_ip”:”192.168.165.152″,
“hostname”:”test”,
“exe_md5″:”d99a695d2dc4b5099383f30964689c55”
}

User Login Alert

{
“data_type”:”1001″,
“status”:”Failed”,
“type”:”password”,
“user_exsit”:”false”,
“user”:”sad”,
“from_ip”:”192.168.165.1″,
“port”:”63089″,
“processor”:”ssh2″,
“time”:”1578405483119″,
“local_ip”:”192.168.165.128″,
“hostname”:”localhost.localdomain”
}

PROC File Hook Alert

{
“uid”:”-1″,
“data_type”:”700″,
“module_name”:”autoipv6″,
“hidden”:”0″,
“time”:”1578384987766″,
“local_ip”:”192.168.165.152″,
“hostname”:”test”
}

Syscall Hook Alert

{
“uid”:”-1″,
“data_type”:”701″,
“module_name”:”diamorphine”,
“hidden”:”1″,
“syscall_number”:”78″,
“time”:”1578384927606″,
“local_ip”:”192.168.165.152″,
“hostname”:”test”
}

LKM Hidden Alert

{
“uid”:”-1″,
“data_type”:”702″,
“module_name”:”diamorphine”,
“hidden”:”1″,
“time”:”1578384927606″,
“local_ip”:”192.168.165.152″,
“hostname”:”test”
}

Interrupts Hook Alert

{
“uid”:”-1″,
“data_type”:”703″,
“module_name”:”syshook”,
“hidden”:”1″,
“interrupt_number”:”2″,
“time”:”1578384927606″,
“local_ip”:”192.168.165.152″,
“hostname”:”test”
}

About Performance of AgentSmith-HIDS

Testing Environment:

CPU	Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz 2 Core
RAM	2GB
OS/Kernel	Centos7 / 3.10.0-1062.7.1.el7.x86_64

Testing Result:

Hook Handler	Average Delay(us)
execve_entry_handler	10.4
connect_handler	7.5
connect_entry_handler	0.06
recvfrom_handler	9.2
recvfrom_entry_handler	0.17
fsnotify_post_handler	0.07