More than a Byte

How hackers get privileged access to IT systems

• By Márton Illés
• Dec 01, 2013

Cybercrime is on the rise, and sensitive, corporate information is one of the top targets of external and internal attacks. Most organizations are prepared to protect their data with firewalls, IPS, IDS, DLP, IAM, SIEM and other systems, but they are not prepared for advanced, persistent threats.

It is no coincidence that several compliance regulations, such as PCI-DSS, specify rules for monitoring the activities of employees, especially those having privileged rights. The most costly and dangerous cyber- attacks are made by using privileged accounts, as these accounts have access to all sensitive information. No wonder privileged identities have emerged as the primary target for cyber-attacks and have been exploited to perpetrate the most destructive data breaches in recent years.

For this reason, BalaBit IT Security hosted a hacker competition last summer with the most-popular Hungarian IT security blog, Buhera Blog, and the professional, ethical hacking company, Silent Signal. The aim was to provide a framework, “Ghost in the Shell Control Box: The Ultimate Hacker Playground,” where anyone, such as university students or security professionals, could try to get privileged access to a sample IT system. The most successful players were awarded.

All the hackers’ activities were tracked by Shell Control Box, a privileged access monitoring appliance. This transparent device records activities in movie-like audit trails that can be searched and replayed. With Shell Control Box, it is possible to monitor what is happening in the IT system and prevent malicious user activities in real-time, either external or internal, and even those initiated by users with the highest privileges.

Our analysis is based on more than 17,000 high-quality, tamper-proof and confidential audit trail files (6.6 GB), recorded by Shell Control Box during the one-week competition. The audit trails can be used as evidence in cases of troubleshooting or forensics investigations.

The Ultimate Hacker Playground

The hackers’ playground, based on an existing, global, financial institution’s IT system, where exactly one server of a local subsidiary was copied with all IT services and security tools, consisted of four levels. The task was to get root access to the server on each level. The server ran a content management system, a project management system and a web management interface of a backend database, serving the CMS and PMS. A firewall was implemented with stricter restrictions than generally used, and the server was able to filter the most widespread, automated, offensive tools so that some basic intrusion prevention system and intrusion detection system functionalities were covered.

The Mission: Get Privileged Access

Organizers of the hacker competition tracked each user’s activities, and thanks to Shell Control Box, it is now possible to model the whole process of getting privileged rights from first entry to root access.

Nearly 400 hackers including engineering students, IT and IT security professionals, and employees of IT security vendors took part in the competition. Only a small percent used TOR anonymity networks, even though they knew their activities were tracked.

Nine percent of the hacker players were able to complete at least the first level and get privileged access to the target server. Six percent of the players were able to complete all four levels. Half of those who completed all four levels did so within 24 hours; the fastest player finished within 7 hours.

Methods for Breaking into the IT System

Compared to log-based forensics, the visualizing capability of Shell Control Box significantly reduced the time required to reconstruct the event. It can be seen that:

• There were two possible ways to complete the first level of the hackers’ playground. Forty-five percent of the hackers were able to discover the vulnerability of the project management software. Sixty-two percent could upload files to the server through this vulnerability, and 7 percent could bypass the restrictions. (PHP files were not allowed to upload).
• Another possible option was to get root access through the content management system. Nearly 25 percent of the hackers were able to notice a backup configuration file that was left behind in the system. Most wasted time trying to break the password database, although it was possible to add new users.
• Another 32 percent used SQL injection to get information, preferring to use automated tools and web scanners. The most popular tools were SQLmap, SQL Power Injector and bsqlb.
• In many cases, PHP shells were downloaded from untrusted sources, which meant that approximately 2 percent of the hackers used shells that “call home” and open a door for the creator of the shell. Using one of these untrusted shells, a Turkish robot could get into the IT system and upload the main page of their website[u1].

Although the vulnerabilities of the example company were immediately patched after being discovered, the fact is that it was copied from a real IT system. There was a time when such vulnerabilities existed in that IT system, and this gives us a reason to focus more on the security.

Lesson Learned

From the results of the hacker competition, you can see how easy it could be to get privileged access. This highlights the importance of monitoring the privileged users’ activities through the commonly-used, administrative protocols (SSH, RDP, HTTP, Citrix, VNC, Telnet) and differentiating the usual behavior from the unusual in real-time.

Although monitoring the actions of privileged users has become a key part of enterprise risk management, it is a challenging exercise. The following best practices can give a helping hand to mitigate the risks related to super users. To gain real benefits from a Privileged Activity Monitoring (PAM) solution:

Adopt the least-privilege principle. Give a user account only those privileges that are essential to that user’s work.

Use unlimited access only in emergency situations. Generally, system administrators do not need unlimited access to the systems they manage. Lock your super user accounts (root, admin, system, and so on), and use them only if absolutely needed.

Personalize every single account. Make personal accountability possible among privileged users. The first step is to minimize the number of shared accounts. The second rule is that sharedaccount passwords must not be shared. Then, go on with the elaboration of functional areas, detecting incompatibilities and segregating duties.

Limit the number of systems in scope for each person’s privileged accounts. System administrators should have super user privileges only on the systems that are needed, those consistent with business and operational needs. This is a common audit recommendation.

Build a central user monitoring infrastructure. Log management or SIEM solutions do not capture all the necessary information. The easiest way to eliminate these blind spots is to use a PAM solution that augments the existing logs by showing precisely what the user did as opposed to the technical results of what he did.

Implement an independent and transparent activity monitoring device. Implement an independent PAM tool that operates transparently and extracts the audit information directly from the communication between the client and the server. This prevents anyone from modifying the audited information—not even the administrator of the device can tamper with the encrypted audit trails.

Use strong authentication and authorization for privileged accounts. Where super user privileges are assigned to personal accounts, protect those accounts with strong authentication methods. To avoid accidental misconfiguration and other human error, certain PAMs support the 4-eyes authorization principle. This is achieved by requiring an “authorizer” to track administrator actions on the server.

Control remote access in detail. The most secure way is to control who can access what and when based on the protocol being used. With the right PAM solution, it is possible to control filetransfers and other unusual traffic. For example, protocol channels, such as disk sharing, port-forwards or file-transfers, can be allowed or denied based on the group-membership of the user or the time of day.

Prevent malicious actions in real-time. Advanced PAM solutions can monitor the traffic of remote connections in real time, and execute various actions if a certain pattern (for example, a suspicious command or text) appears in the command line or on the screen.

In case of risky user action, the device can send an email alert or immediately terminate the connection. For example, the connection can be blocked before a harmful administrator command, such as “delete,” is executed on the server.

Improve forensics with movie-like playback and fast search. Advanced PAM tools can replay recorded sessions just like a movie, and all actions of the users can be seen exactly as they appeared on the monitor. These tools enable fast forwarding during replays, searching for events via typed commands or pressing “Enter” and texts seen by the user. In case of any problems like database manipulation, unexpected shutdown, etc., the circumstances of the event are available in the audit trails; thus, the cause of the incident can be easily identified.

This article originally appeared in the December 2013 issue of Security Today.