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EventTracker and Shellshock

What’s your thought on Shellshock? EventTracker CEO A.N. Ananth weighs in.

Summary:

  • Shellshock (also known as Bashdoor) CVE-2014-6271 is a security bug in the Linux/Unix Bash shell.
  • EventTracker v 6.x, v7.x is NOT vulnerable to Shellshock as these products are based on the Microsoft Windows platform.
  • ETIDS and ETVAS which are offered as options of the SIEM Simplified service, are vulnerable to Shellshock, as these solutions are based on CentOS v6.5. Below are the links relevant to this vulnerability.
  • If you subscribe to ETVAS and/or ETIDS, the EventTracker Control Center has already initiated action to patch this vulnerability on your behalf. Please contact ecc@eventtracker.com with any questions.

Details:

Shellshock (also known as Bashdoor) CVE-2014-6271 is a security bug in the broadly used Unix Bash shell. Bash is used to process certain commands across many internet daemons. It is a program that is used by various Unix-based systems to execute command scripts and command lines. Often it is installed as the system’s default command line interface.

Notes:

  • Environment variables (each running program having its own list of name/value pairs) occur in Unix-based and other operating systems that Bash supports. When one program is started by an earlier program, an initial list of environment variables is provided by the earlier program to the new program. Apart from this, named scripts (internal list of functions) are also maintained by Bash that can be executed from within.
  • By creating vulnerable versions of Bash, an attacker can gain unauthorized access to a computer system. By executing Bash with a chosen value in its environment variable list, vulnerable versions of Bash can be caused, that may allow remote code execution.
  • Scrutiny of the Bash source code history, reveal that concealed vulnerabilities have been present since approximately version 1.13 (1992). Lack of comprehensive change logs do not allow, the maintainers of Bash source code, to pinpoint the exact time of introduction of the vulnerability.

We don’t need no stinkin Connectors

#36 on the American Film Institute list of Top Movie Quotes is “Badges? We don’t need no stinkin badges” which has been used often (e.g., Blazing Saddles). The equivalent of this in the log management universe is a “Connector”. We are often asked how many “Connectors” we have readily available or how long it takes to develop a Connector.

These questions stem from a model used by programs such as ArcSight which depend on Early Binding. In an earlier era of computing, Early Binding was needed for the compiler could not create an entry in the virtual method table for the procedure being compiled. It has the advantage of being efficient, an important consideration when CPU and memory are in very short supply, like years ago.

Just in time languages such as .NET or Java adopt Late Binding where the v-table is computed at run time. Years ago, Late Binding had negative connotations in terms of performance but that hasn’t been true for at least 20 years now.

Early binding requires a fixed schema to be mandated for all possible entries and for input to be “normalized” to this schema. The benefit of the fixed plan is efficiency in output since the data is already normalized. While that may make some sense for compilers, input in formalized language grammars makes almost no sense in the log management universe, where the input is log data from sources that do not adopt any standardization at all. The downside of such an approach is to require a “Connector” to normalize a new log source to the normalized schema. Another consideration is that outputs can greatly vary depending on usage – there are many possible uses for the data, the limitation is only the users imagination. The Early Binding model however, is designed with fixed outputs in mind. These disadvantages limit such designs.

In contrast, EventTracker uses Late Binding, where the meaning of tokens can be assigned at output (run) time, rather than being fixed at receive time. Thus new log formats do not need a “Collector” to be available at ingest time. The desired output format can be specified at search or report time for easy viewing. This requires somewhat greater computing capacity with Moores Law to the rescue. Late Binding is the primary advantage of EventTrackers’ “Fast In, Smart Out” architecture.

Spray & Pray or 80/20

If you spend any time at all looking at log data from any server that is accessible to the Internet, you will be shocked at the brazen attempts to knock the castle over. They being within minutes of the server being available. They most commonly include port scans, login attempts using default username/password, web server attacks described by OWASP.

How can this possibly be? Given the sheer number of machines that are visible on the Internet? Don’t these guys have anything better to do?

The answer is automation and scripted attacks, also known as spray and pray. The bad guys are capitalists too (regardless of country of origin!) and need to maximize their effort, computing capacity and network bandwidth usage. Accordingly, they use automation to “knock on all available doors in a wealthy neighborhood” as efficiently and regularly as possible. Why pick on servers in developed countries? Because that’s where the payoff is likely to be higher. Its Risk v. Reward all the way.

The automated (first) wave of these attacks is to identify vulnerable machines and establish presence. Following waves may be staffed depending on the the location and identity and thus the potential value to be obtained by a greater investment of (scarce) expertise by the attacker.

Such attacks can be deterred quite simply by using secure (non-default) configuration, system patching and basic security defenses such as firewall and anti-virus. This explains the repeated exhortations of security pundits on “best practice” and also the rationale behind compliance standards and auditors trying to enforce basic minimum safeguards.

The 80/20 rule applies to attackers just as it does to defenders. Attackers are trying to cover 80% of the ground at 20% of the cost so as to at-least identify soft high value targets and at most steal from them. Defenders are trying to deter 80% of the attackers at 20% of cost by using basic best practices.

Guidance such as SANS Critical Controls or lessons from Verizon’s Annual Data Breach studies can help you prioritize your actions. Attackers depend on the fact that the majority of users do not follow basic security hygiene, don’t collect logs which would expose the attackers actions and certainly never actually look at the logs.

Defeating a “spray and pray” attacks requires basic tooling and discipline. The easy way to so this? We call it SIEM Simplified. Drop us a shout, it beats being a victim.

Hackers: What they are looking for and the abnormal activities you should be evaluating

Most hackers are looking into critical data for credential theft. A credential theft attack is when an attacker initially gains privileged access to a computer on a network and then uses freely available tooling to extract credentials from the sessions of other logged-on accounts. The most prevalent target for a credential theft is a “VIP account.” VIP account’s consist of contacts with highly sensitive data attached: access to accounts and secure data that many others within that organization probably don’t have.

It’s very important for administrators to be conscious of activities that increase the likelihood of a successful credential-theft attack.

These activities are:
• Logging on to unsecured computers with privileged accounts
• Browsing the Internet with a highly privileged account
• Configuring local privileged accounts with the same credentials across systems
• Overpopulation and overuse of privileged domain groups
• Insufficient management of the security of domain controllers.

There are specific accounts, servers, and infrastructure components that are the usual primary targets of attacks against Active Directory.

These accounts are:
• Permanently privileged accounts
• VIP accounts
• “Privilege-Attached” Active Directory accounts
• Domain controllers
• Other infrastructure services that affect identity, access, and configuration management, such as public key infrastructure (PKI) servers and systems management servers

Although pass-the-hash (PtH) and other credential theft attacks are ubiquitous today, it is because there is freely available tooling that makes it simple and easy to extract the credentials of other privileged accounts when an attacker has gained Administrator – or SYSTEM-level access to a computer.

Even without this tool, an attacker with privileged access to a computer can just as easily install keystroke loggers that capture keystrokes, screenshots, and clipboard contents. An attacker with privileged access to a computer can disable anti-malware software, install rootkits, modify protected files, or install malware on the computer that automates attacks or turns a server into a drive-by download host.

The tactics used to extend a breach beyond a single computer vary, but the key to propagating compromise is the acquisition of highly privileged access to additional systems. By reducing the number of accounts with privileged access to any system, you reduce the attack surface not only of that computer, but the likelihood of an attacker harvesting valuable credentials from the computer.