Anatomy of a Spearphishing Attack

July 30, 2012 Tags: apt attack, attack explained, email attack, intrusion process cycle, spearphishing, spearphishing attack, spoofed email
Category: APT, Cyber Security, hacking, In the News, Video Comments Off

In blogs past, we have discussed the importance of Cyber Security, and how it is one of the most important pieces of the Information Assurance puzzle. One of the greatest problems that we continue to face as Network Defenders and Information Assurance professionals is human error. We spend millions of dollars on technologies built to protect, block and alert when our IT systems come under fire, but many times the user is the very reason why we are under attack.

The Target, The User

The user is a soft, fleshy decision-making machine with something our computing systems do not have; free will. It’s that very free will that empowers the user to decide whether to open an email and its attachment, or click on a link that appears legitimate or report the email as a potential spearphishing attempt. Easily fooled, caught off guard or simply unaware of the potential threat, the user continues to be the easiest and least difficult control to bypass to gain access to your internal network.

Technical Controls vs. User Awareness

Technical controls can only offer so much protection from and for the user. That means the gaps in protection against social engineering type attacks are not only technical, but also educational and awareness related. Only when your users are more informed and aware of their susceptibility toward socially engineered attacks will they exercise proper caution before opening emails or clicking a web link. There is no silver bullet in any situation where security is a concern, it must be developed and implemented in layers. Multiple layers can add to the difficulty, security education and awareness training is one layer.

The Attacker

It takes an adversary very little time to craft a believable message that will entice a user to click on a link or open an attachment. Below is a typical, high level process used by most adversaries before, during and after an attack. This process is common among attackers of all skill levels, including Advanced Persistent Threats, and is extremely repeatable.

The Processes Defined

The process starts with the attacker identifying a target, and then researching the target to gain as much information as possible. Generally, all the attacker needs is a name, an email address and some personal information (e.g. company or business, personal interests or hobbies). From there, the adversary creates a believable spearphish email message written in a way to entice the target to open the message and access the link. The attacker may spoof the sender to appear as a friend or even a family member, increasing the likelihood of compromise

Sourcing Information – Is simply the process of choosing a target and performing research on that target. The information is collected in a way that doesn’t alert the target to the research (i.e. search engines, online white pages, social network sites). Having information about the target provides the means to craft a personal message that is convincing enough to get the target to perform the desired action (open an attachment, or click on a web link within an email).
Crafting the Spearphish – Working with the information collected on the target, the spearphishing message should be crafted in such a way that the target believes it to be legitimate.
Obtaining Access – Is the initial compromise of the host, either through an infected, malicious attachment or a web link to a malicious website with a browser or java exploit embedded. This initial access is used to give the adversary its vector for follow-on actions after the initial exploitation. Elevating privileges, creating services and registry keys are just a few possible follow-on actions.
Stealing Data – Pretty much speaks for itself. Once in, the attacker begins interrogating the compromised host for anything of interest. MS Word files, Excel spreadsheets, Adobe PDF files and plain text files are immediate targets for data ex-filtration. Due to the type of access the attacker may have, the initial action may be akin to a “smash & grab” type robbery. If the attacker is not concerned about being caught or losing persistence, then they may scrutinize the data they want to steal more heavily. Every byte that leaves the compromised host potentially puts the attackers at risk of being caught.
Moving Laterally – This is a common phrase within the CND community as well as Penetration Testers to describe the movement from the initial compromised host to another host on the same network. The idea behind lateral movement has several benefits to attackers which include removing themselves and their actions from the initial vector of compromise (most likely to be detected), or gaining access to additional information and information systems not available to the initial compromised host. Another thing worth mentioning about moving laterally within a network is that the deeper the attacker gets, the harder it is to fully remove their access. If the attacker can spread across the network, there is an increased chance that some access will remain even after the intrusion is detected.
Maintaining Access – Although the position in the process varies when the attacker moves to maintain their access beyond their initial attack vector, it is an essential part of the process for long-term access. If the attacker was not able to obtain the information they were seeking during the initial attack, they will need to return to continue looking. They may also have a particular system in mind that they are attempting to gain access to, so persistent backdoors will provide the attacker time to get to their intended destination.
Analyzing the Stolen Data – This part of the process is where the attacker can spend time going through the data they were able to remove from the compromised host or hosts network. If the attacker is satisfied with the information they may have, there is no need to return to the intrusion. This rarely is the case. More often than not, there is more to steal. It helps if the victim is completely unaware of the attacker’s presence.