Using systemd to squash THP and start splunk enterprise

Updated Jan, 16, 2018 user security issue

Updated Jan 19,2018 using forking type for splunk

Fixing INIT Scripts

If you are currently or prefer using init script startup to remain as close to “out of box” configuration as possible be aware of a serious security risk present in the traditional startup method.  REF: https://www.splunk.com/view/SP-CAAAP3M To mitigate the issue and address THP/Ulimits consider moving to a field modified version of the script. https://bitbucket.org/snippets/rfaircloth-splunk/Gek8My

Going forward using SYSTEMD

 

The concept presented in this post, as well as the original inspiration, have some risks. Using alternatives to the vendor provided init scripts have support risks including loss of the configuration by future upgrades. Each operating system vendor has their own specific guidance on how to do this, each automation vendor has example automation scripts as well. Picking an approach that is appropriate for your environment is up to you.

THP the bain of performance for so many things in big data is often left on by default and is slightly difficult to disable. As a popular Splunk answers post and Splunk consultants include Marquis have found the best way to ensure ulimit and THP settings are properly configured is to modify the init scripts. This is a really crafty and reliable way to ensure THP is disabled for Splunk, it works on all Linux operating systems regardless of how services are started.

I’m doing some work with newer operating systems and wanted to explore how systemd really works and changes what is possible in managing a server. Lets face it systemd has not gotten the best of receptions in the community, after all it moved our cheese, toys and the ball all at once. It seems to be here to stay what if we could use its powers for good in relation to Splunk. Let’s put an end to THP and start Splunk the systemd native way.

Note: the following config file is present for readability and google. Downloadable text file is available https://bitbucket.org/snippets/rfaircloth-splunk/ze7rqL

Create the file /etc/systemd/system/disable-transparent-huge-pages.service


[Unit]
Description=Disable Transparent Huge Pages

[Service]
Type=oneshot
ExecStart=/bin/sh -c “echo never >/sys/kernel/mm/transparent_hugepage/enabled”
ExecStart=/bin/sh -c “echo never >/sys/kernel/mm/transparent_hugepage/defrag”
RemainAfterExit=true
[Install]
WantedBy=multi-user.target

Verify THP and defrag is presently enabled to avoid a false sense of success

# cat /sys/kernel/mm/transparent_hugepage/enabled

[always] madvise never

# cat /sys/kernel/mm/transparent_hugepage/defrag

[always] madvise never

Enable and start the unit to disable THP

# systemctl enable disable-transparent-huge-pages.service

# systemctl start disable-transparent-huge-pages.service

# cat /sys/kernel/mm/transparent_hugepage/enabled

always madvise [never]

# cat /sys/kernel/mm/transparent_hugepage/defrag

always madvise [never]

Reboot and repeat the verification to ensure the process is enforced

Note: the following config file is present for readability and google. Downloadable text file is available https://bitbucket.org/snippets/rfaircloth-splunk/xe7rqj

create the unit file /etc/systemd/system/splunk.service

<p class="p1"><span class="s1">[unit]</span></p>
<p class="p1"><span class="s1">After=network.target</span></p>
<p class="p1"><span class="s1">Wants=network.target</span></p>
<p class="p1"><span class="s1">Description=Splunk Enterprise</span></p>
<p class="p1"><span class="s1">[Service]</span></p>
<p class="p1"><span class="s1">Type=forking</span></p>
<p class="p1"><span class="s1">RemainAfterExit=False</span></p>
<p class="p1"><span class="s1">User=splunk</span></p>
<p class="p1"><span class="s1">Group=splunk</span></p>
<p class="p1"><span class="s1">ExecStart=/opt/splunk/bin/splunk start --answer-yes --no-prompt --accept-license</span></p>
<p class="p1"><span class="s1">ExecStop=/opt/splunk/bin/splunk stop</span></p>
<p class="p1"><span class="s1">PIDFile=/opt/splunk/var/run/splunk/splunkd.pid</span></p>
<p class="p1"><span class="s1">Restart=always</span></p>
<p class="p1"><span class="s1">TimeoutSec=300</span></p>
<p class="p1"><span class="s1">#ulimit -Sn 65535</span></p>
<p class="p1"><span class="s1">#ulimit -Hn 65535</span></p>
<p class="p1"><span class="s1">LimitNOFILE=65535</span></p>
<p class="p1"><span class="s1">#ulimit -Su 20480</span></p>
<p class="p1"><span class="s1">#ulimit -Hu 20480</span></p>
<p class="p1"><span class="s1">LimitNPROC=20480</span></p>
<p class="p1"><span class="s1">#ulimit -Hf unlimited</span></p>
<p class="p1"><span class="s1">#ulimit -Sf unlimited</span></p>
<p class="p1"><span class="s1">LimitFSIZE=infinity</span></p>
<p class="p1"><span class="s1">LimitCORE=infinity</span></p>
<p class="p1"><span class="s1">[Install]</span></p>
<p class="p1"><span class="s1">WantedBy=multi-user.target</span></p>

# systemctl enable splunk.service

# systemctl start splunk.service

Verify the ulimits have been applied via splunk logs

#cat /opt/splunk/var/log/splunk/splunkd.log | grep ulimit

Reboot and repeate all verifications

Bonus material, kill Splunk (lab env only) and watch systemd bring it back

# killall splunk

# ps aux | grep splunk

Splunk OS Data on boarding – best practices updated

I’ve updated my best practices a bit and moved the implementation guides from confluence out to the bitbuckets in markdown so they can be more easily referenced on any platform or secured environments where PDFs might be discouraged.

Each repo will contain a README.md and one or more INSTALL.md files with the implementation guides. If you find an issue have a better practice or other enhancement, please open an issue in the repositories tracker.

Trust but verify – your logs might be lieing to you aka, the case for network tap traffic monitoring

I really do “get” it, logging and monitoring can be very costly, we all agree not nearly as costly as a breach. Each organization is struggling to ensure they log enough to see detection and value while being good stewards of their company budget. It has been a day reading vault 7 leaks and I see honestly not much that surprises me. I do see something worth a strong restatement, that is an encouragement to rethink what you log and how you log it. The CIA has a very cool (sorry hacker at heart) tool we have known about for some time but have not been able to talk about. Their tool “Drillbit” allows the creation of a covert tunnel using common cisco gear in such a way typical monitoring and logging using IDS and firewalls will not identify. American companies should note criminal gangs and foreign governments certainly have similar capabilities. Splunk has your back if you are willing to let us. Using Splunk Stream and proper sensor placement we can collect data from the inside and outside of your firewall that can be used to identify covert tunnels. Detection should be performed three approaches. The danger these leaks are presenting you is an increased awareness of the effectiveness of these techniques, encouraging the advancement of commodity cybercrime toolkits with ever more difficult to detect features. Don’t use cisco, sorry bad news is almost every major gear vendor has been exploited with similar approaches

  • Static Rules such as
    • This not that “Stream identified traffic not in firewall logs”
    • New patterns in DNS, NTP, GRE flows
    • Change/login to firewall or switch not associated with a change record
  • Threat List Enrichment and detection
    • Source and Destination traffic on quality threat lists. Traffic for protocols other than http(s) and DNS should be treated with high or critical priority
  • Machine Learning
    • Anomalous  egress traffic by source from network devices
    • Anomalous admin connections by source to network devices

Automating Splunk deployment for RedHat/Centos (poor man’s edition)

I pulled this out of the archives , on request notice this was originally developed for Splunk 6.2.x and RHEL 7.0. Please review the details make sure it is suitable for you and TEST. If I can talk you out of doing things this way I would. Salt is a great way to manage app config its free and just awesome.

Title: Splunk Universal Forwarder Version 6.2.3+ Red Hat Enterprise Linux 7

Author: Ryan Faircloth 

Summary: Using repositories for version managment of the Splunk Universal Forwarder assists in ensuring managed Red Hat and compatible linux  systems are using the approved version of the software at all times. 

[TOC]

## Setup the repository server ##
1. Install createrepo  and nginx ``` yum install createrepo apache2 ```
3. Create a user to work with the repository 

	``` 
	sudo adduser  repouser 
	```  
3. Change user to our repouser user all commands for the repository should be executed using this ID 

	 ``` 
	 sudo su - repouser
	 ```

## Generate GPG Keys ##
1. Change user to our repouser user all commands for the repository should be executed using this ID 

	```
	sudo su - repouser 
	```
2. Create the default configuration for gpg by running the command 

	```
	gpg --list-keys
	``` 
3. Edit ~/.gnupg/gpg.conf 
	* uncomment the line ``` no-greeting ```
	* add the following content to the end of the file 
	
	```
	# Prioritize stronger algorithms for new keys.
	default-preference-list SHA512 SHA384 SHA256 SHA224 AES256 AES192 AES CAST5 BZIP2 ZLIB ZIP UNCOMPRESSED
	# Use a stronger digest than the default SHA1 for certifications.
	cert-digest-algo SHA512
	```
	
4. Generate a new key with the command ``` gpg --gen-key ```
5. Select the folowing options ON CENTOS/RHEL this procedure must be executed on the console or SSH having logged in as the repouser
	1. Type of key "(1) RSA and RSA (default)"
	2. Key size "4096"
	3. Expires "10y"
	4. Confirm "Y"
	5. Real Name "Splunk local repository"
	6. Email address on repository contact this generally should be an alias or distribution list
	7. Leave the comment blank
	8. Confirm and "O" to Okay
	9. Leave passphrase blank and confirm, a key will be generated not the sub KEY ID in the following example * E507D48E * 

	```
	gpg: checking the trustdb
	gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
	gpg: depth: 0  valid:   1  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 1u
	gpg: next trustdb check due at 2025-05-24
	pub   4096R/410E1699 2015-05-27 [expires: 2025-05-24]
    	  Key fingerprint = 7CB8 81A9 E07F DA7B 83FF  2E1B 8B31 DA83 410E 1699
	uid                  Splunk local repository <repo@example.com>
	sub   4096R/E507D48E 2015-05-27 [expires: 2025-05-24]
	```	
10. Export the signing keys public component save this content for use later

	```
	gpg --export --armor KEY_ID >~/repo.pub 
	``` 
11. Install the new key into the RPM database

```
sudo cp ~/repo.pub /etc/pki/rpm-gpg/RPM-GPG-KEY-splunkrepo
sudo rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-splunkrepo
```
12. Configure RPM signing with the new key

```
echo "%_signature gpg" > ~/.rpmmacros
echo "%_gpg_name splunkrepo" >> ~/.rpmmacros
``

13. Create a repository

```
mkdir /opt/splunkrepo
cp splunkforwarder*.rpm /opt/splunkrepo
createrepo /opt/splunkrepo
```
14. Configure the local repository create the following configuration /etc/yum.repos.d/splunk.repo

```
[splunkrepo]
name=splunk repository
baseurl=file:///opt/splunkrepo/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-splunkrepo
enabled=1
```
15. Test the local repository by installing splunkforwarder

```
sudo yum update
sudo yum install splunkforwader
```
Note: Create a configuration RPM refer to https://fedoraproject.org/wiki/How_to_create_an_RPM_package and https://www.redhat.com/promo/summit/2010/presentations/summit/opensource-for-it-leaders/thurs/pwaterma-2-rpm/RPM-ifying-System-Configurations.pdf for more information do not run as root sudo to repouser
17.  Prepare the rpm tree ``` rpmdev-setuptree ```
18.  Create a spec file with the following content ~/splunkforwarder-baseconfig.spec

```
#--------------------------------------------------------------------------
# This spec file is Copyright 2010, My Company, Inc.
#--------------------------------------------------------------------------
Summary: My Company general configuration RPM
Name: splunkforwarder-baseconfig
Version: 1
Release: 3
License: Copyright 2010, My Company, Inc.
Group: MyCompany/Configs
Packager: Packager Name <my-email@mycompany.com>
requires: splunkforwarder
BuildArch: noarch
%description
This RPM provides general services and security configuration for My Company.

%triggerin -- splunkforwarder
/opt/splunkforwarder/bin/splunk enable boot-start --accept-license --answer-yes 
service splunk stop
if [ -d "/opt/splunkforwarder/etc/apps/org_all_deploymentclient/local" ]
then
    echo "Directory /opt/splunkforwarder/etc/apps/org_all_deploymentclient/local exists."
else
    mkdir -p /opt/splunkforwarder/etc/apps/org_all_deploymentclient/local    
fi
echo #Base deployment configuration >/opt/splunkforwarder/etc/apps/org_all_deploymentclient/local/deploymentclient.conf
echo [deployment-client] >>/opt/splunkforwarder/etc/apps/org_all_deploymentclient/local/deploymentclient.conf
#echoclientName  >>/opt/splunkforwarder/etc/apps/org_all_deploymentclient/local/deploymentclient.conf
echo [deployment-client] >>/opt/splunkforwarder/etc/apps/org_all_deploymentclient/local/deploymentclient.conf
echo targetUri = ds.example.com:8089 >>/opt/splunkforwarder/etc/apps/org_all_deploymentclient/local/deploymentclient.conf

service splunk start


%triggerun -- splunkforwarder
if [ $1 -eq 0 -a $2 -gt 0 ] ; then
 /opt/splunkforwarder/bin/splunk stop
 /opt/splunkforwarder/bin/splunk disable boot-start
 rm -Rf /opt/splunkforwarder/etc/apps/org_all_deploymentclient
fi
%files

```
18.  Build the RPM ``` rpmbuild -sign -ba splunkforwarder-baseconfig.spec ```
19. Copy the RPM to the repository cp ~/rpmbuild/RPMS/noarch/splunkforwarder-baseconfig-1-3.noarch.rpm / /opt/splunkrepo
20. Update repository DB ``` createrepo /opt/splunkrepo ```
21. Test the rpms

```
yum update
yum install splunkforwarder-baseconfig
```
22. Configure a web server (Apache) for use as a repository server
23.  Set permissions on the repository folder ``` chmod -R 755 /opt/splunkrepo ```
24. Create the web server configuration file with the following contents /etc/http/conf.d/splunkrepo.conf

```
Alias /splunkrepo/ "/opt/splunkrepo/"

<Directory "/opt/splunkrepo">
   Options Indexes FollowSymLinks MultiViews
   AllowOverride All
   Require local
   Order allow,deny
   Allow from all
</Directory>
```
25. Reload (or restart) the web server ```service httpd reload ```
26. Test `` lynx http://localhost/splunkrepo/repodata/repomd.xml ```
27. Enable the new repository on the first test client

```
sudo yum-config-manager --add-repo http://localhost/splunkrepo
sudo yum update
sudo yum install splunkforwarder-baseconfig
```

Splunk the server and the enpoint aka “All the Things”

I’m sharing something today that has been available thanks to many in white papers and presentations dealing with identification of malicious code and activities in your windows event data. Shout out to everyone from our “friends” at the NSA, to Splunk .Conf presenters and malwarearcheology.com just to name a few.

The PDF attached is a portion of the next evolution of the Use Case Repository I maintain at Splunk. Along with the reference TAs and inputs, this will allow you to quickly and consistently collect very valuable data supporting security use cases at multiple levels of maturity. If it seems like too much don’t work Splunk Pro Services and partners are able to help you get this visibility just contact your account team.

Standard disclaimer, this is a blog post, I built the content from public non-warrantied information, and this is still public non-warrantied information, your situation might not match the advice given.

PT005-Microsoft-Windows

Good Assets and Identities make for big bundles

Having great and informative data will make for some hefty lookups. I’ve heard from a few customers that run into this rather than plan for it so let us talk about the levers we need to pull.

  • Don’t wait around upgrade to Splunk Enterprise 6.5.2+ Now is the time
  • Don’t wait any longer upgrade to Splunk Enterprise Security 4.5.1 the dev team invested in improvements to assets and identities lookups that also improve by decreasing the size of the merged lookups.
  • Update server.conf on the indexers and search head cluster peers.

[httpServer]

max_content_length = 1610612736 # 1.5 GB

  • Update distsearch.conf to better replication on the SH/SHC
[replicationSettings]
# 1.5 GB with encoding room this will increase the memory utilization while decreasing CPU utilization
maxMemoryBundleSize = 1700 
#1.5 GB to match server.conf on the other side
maxBundleSize = 1536

RSYSLOG read the docs

Ok, I said posts in threes so here it is. We all know RYSLOG config is much more painful than syslog-ng but for reasons beyond all of our control, it is readily available for more customers than syslog-ng is today. Thanks to Splunk users I want to share a couple links to better doc to make this not so awful

  • RedHat https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/s1-basic_configuration_of_rsyslog.html
  • Usenix https://www.usenix.org/system/files/login/articles/06_lang-online.pdf

thank you @mattymo and @lowell via Splunk Slack chat

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