OSSEC Documentation Release 2.7.1 Jeremy Rossi Jul 21, 2017 Contents 1 Manual & FAQ 3 1.1 Manual..................................................3 1.2 Frequently asked questions........................................ 85 1.3 User submitted Cookbooks........................................ 99 2 Development 101 2.1 oRFC: 1 The Collective Code Construction Contract (C4)....................... 101 2.2 oRFC: 2 Coding Style Guide....................................... 104 3 Reference 107 3.1 Syntax and Options............................................ 107 3.2 Output Formats.............................................. 149 3.3 Man pages................................................ 150 3.4 What’s new................................................ 177 3.5 Rootcheck / Syscheck Reference..................................... 178 3.6 Glossary................................................. 183 4 Indices and tables 185 i ii OSSEC Documentation, Release 2.7.1 OSSEC is an Open Source Host-based Intrusion Detection System. It performs log analysis, integrity checking, Windows registry monitoring, rootkit detection, real-time alerting and active response. It runs on most operating systems, including Linux, OpenBSD, FreeBSD, Mac OS X, Solaris and Windows. A list with all supported platforms is available at: Supported Systems Contents 1 OSSEC Documentation, Release 2.7.1 2 Contents CHAPTER 1 Manual & FAQ Manual Getting started with OSSEC OSSEC is a full platform to monitor and control your systems. It mixes together all the aspects of HIDS (host-based intrusion detection), log monitoring and SIM/SIEM together in a simple, powerful and open source solution. It is also backed and fully supported by Trend Micro. Key Benefits Compliance Requirements OSSEC helps customers meet specific compliance requirements such as PCI, HIPAA etc. It lets customers detect and alert on unauthorized file system modifications and malicious behavior embedded in the log files of COTS products as well as custom applications. For PCI, it covers the sections of file integrity monitoring (PCI 11.5, 10.5), log inspection and monitoring (section 10) and policy enforcement/checking. Multi platform OSSEC lets customers implement a comprehensive host based intrusion detection system with fine grained applica- tion/server specific policies across multiple platforms such as Linux, Solaris, AIX, BSD, Windows, Mac OS X and VMware ESX. Real-time and Configurable Alerts OSSEC lets customers configure incidents they want to be alerted on which lets them focus on raising the priority of critical incidents over the regular noise on any system. Integration with smtp, sms and syslog allows customers to be 3 OSSEC Documentation, Release 2.7.1 on top of alerts by sending these on to e-mail and handheld devices such as cell phones and pagers. Active response options to block an attack immediately is also available. Integration with current infrastructure OSSEC will integrate with current investments from customers such as SIM/SEM (Security Incident Manage- ment/Security Events Management) products for centralized reporting and correlation of events. Centralized management OSSEC provides a simplified centralized management server to manage policies across multiple operating systems. Additionally, it also lets customers define server specific overrides for finer grained policies. Agent and agentless monitoring OSSEC offers the flexibility of agent based and agentless monitoring of systems and networking components such as routers and firewalls. It lets customers who have restrictions on software being installed on systems (such as FDA approved systems or appliances) meet security and compliance needs. Key Features File Integrity checking There is one thing in common to any attack to your networks and computers: they change your systems in some way. The goal of file integrity checking (or FIM - file integrity monitoring) is to detect these changes and alert you when they happen. It can be an attack, or a misuse by an employee or even a typo by an admin, any file, directory or registry change will be alerted to you. Covers PCI DSS sections 11.5 and 10.5.5. Log Monitoring Your operating system wants to speak to you, but do you know how to listen? Every operating system, application, and device on your network generate logs (events) to let you know what is happening. OSSEC collects, analyzes and correlates these logs to let you know if something wrong is going on (attack, misuse, errors, etc). Do you want to know when an application is installed on your client box? Or when someone changes a rule in your firewall? By monitoring your logs, OSSEC will let you know of that. Covers PCI DSS section 10 in a whole. Rootkit detection Criminals (also known as hackers) want to hide their actions, but using rootkit detection you can be notified when they (or trojans, viruses, etc) change your system in this way. 4 Chapter 1. Manual & FAQ OSSEC Documentation, Release 2.7.1 Active response Take immediate and automatic responses when something happens. Why wait for hours when you can alert your admin and block an attack right way? OSSEC Architecture OSSEC is composed of multiple pieces. It has a central manager for monitoring and receiving information from agents, syslog, databases, and from agentless devices. Manager (or Server) The manager is the central piece of the OSSEC deployment. It stores the file integrity checking databases, the logs, events, and system auditing entries. All the rules, decoders, and major configuration options are stored centrally in the manager; making it easy to administer even a large number of agents. Note: The manager may be called the OSSEC server, or even just server in this documentation. Agents The agent is a small program, or collection of programs, installed on the systems to be monitored. The agent will collect information and forward it to the manager for analysis and correlation. Some information is collected in real time, others periodically. It has a very small memory and CPU footprint by default, not affecting the system?x80x99s usage. Agent security: It runs with a low privilege user (generally created during the installation) and inside a chroot jail isolated from the system. Most of the agent configuration can be pushed from the manager. Agentless For systems that an agent cannot be installed on, the agentless support may allow integrity checks to be performed. Agentless scans can be used to monitor firewalls, routers, and even Unix systems. Virtualization/VMware OSSEC allows you to install the agent on the guest operating systems. It may also be installed inside some versions of VMWare ESX, but this may cause support issues. With the agent installed inside VMware ESX you can get alerts about when a VM guest is being installed, removed, started, etc. It also monitors logins, logouts and errors inside the ESX server. In addition to that, OSSEC performs the Center for Internet Security (CIS) checks for VMware, alerting if there is any insecure configuration option enabled or any other issue. Firewalls, switches and routers OSSEC can receive and analyze syslog events from a large variety of firewalls, switches and routers. It supports all Cisco routers, Cisco PIX, Cisco FWSM, Cisco ASA, Juniper Routers, Netscreen firewall, Checkpoint and many others. 1.1. Manual 5 OSSEC Documentation, Release 2.7.1 Architecture This diagram shows the central manager receiving events from the agents and system logs from remote devices. When something is detected, active responses can be executed and the admin is notified. Internal Architecture For technical and deep detailed information on how it works, please read the following documents: OSSEC log analysis/inspection architecture (PDF) - by Daniel Cid Support Everyone knows that support and technical expertise are critical in ensuring the success of any product deployment. With an open source project this is not different. If you need enterprise-class commercial support for OSSEC, Trend Micro, the company behind this great open source project, offers this option to our users. For more information, visit the OSSEC commercial support page. Supported Systems OSSEC supports the following operating systems and log formats. Operating Systems The following operating systems are supported by the OSSEC agent: • GNU/Linux (all distributions, including RHEL, Ubuntu, Slackware, Debian, etc) • Windows XP, 2003, Vista, 2008 • VMWare ESX 3.0,3.5 (including CIS checks) • FreeBSD (all current versions) • OpenBSD (all current versions) • NetBSD (all current versions) 6 Chapter 1. Manual & FAQ OSSEC Documentation, Release 2.7.1 • Solaris 2.7, 2.8, 2.9 and 10 • AIX 5.2 and 5.3 • Mac OS X 10.x • HP-UX 11 Devices supported via Syslog These systems/devices are also supported via remote syslog: • Cisco PIX, ASA and FWSM (all versions) • Cisco IOS routers (all versions) • Juniper Netscreen (all versions) • SonicWall firewall (all versions) • Checkpoint firewall (all versions) • Cisco IOS IDS/IPS module (all versions) • Sourcefire (Snort) IDS/IPS (all versions) • Dragon NIDS (all versions) • Checkpoint Smart Defense (all versions) • McAfee VirusScan Enterprise (v8 and v8.5) • Bluecoat proxy (all versions) • Cisco VPN concentrators (all versions) • VMWare ESXi 4.x Devices and Operating Systems via Agentless Using OSSEC agentless options, the following systems are also supported (for log analysis and file integrity checking): • Cisco PIX, ASA and FWSM (all versions) • Cisco IOS routers (all versions) • Juniper Netscreen (all versions) • SonicWall firewall (all versions) • Checkpoint