1.5 Example attacks
The combination of these two trends – increase in complexity and increase in connectivity – results in an attack surface explosion. The following examples shall serve to illustrate this point.
1.5.1 The Mirai botnet
In late 2016, the internet was hit by a series of massive Distributed Denial-of-Service (DDoS) attacks originating from the Mirai botnet, a large collection of infected devices (so-called bots) remote-controlled by attackers.
The early history of the Mirai botnet can be found in [9]: the first bootstrap scan on August 1 lasted about two hours and infected 834 devices. This initial population continued to scan for new members and within 20 hours, another 64,500 devices were added to the botnet. The infection campaign continued in September, when about 300,000 devices were infected, and reached its peak of 600,000 bots by the end of November. This corresponds to a rate of 2.2-3.4 infected devices per minute or 17.6-27.2 seconds to infect a single device.
Now contrast this with a side-channel or fault attack. Even if we assume that the actual attack – that is, the measurement and processing of the side-channel traces or the injection of a fault – can be carried out in zero time, an attacker would still need time to gain physical access to each target. Now suppose that, on average, the attacker needs one hour to physically access a target (actually, this is a very optimistic assumption from the attacker’s perspective, given that the targets are distributed throughout the globe). In that case, attacking 200,000-300,000 devices would take approximately 22-33 years or 270 to 400 months (as opposed to 2 months in the case of Mirai).
Moreover, any remote attack starts at a network interface of the target system. So the first (and, oftentimes, the only) thing the attacker interacts with is software. But software is complex by nature.
1.5.2 Operation Aurora
In mid-December 2009, Google discovered a highly sophisticated, targeted attack on their corporate infrastructure that resulted in intellectual property theft [73]. During their investigation, Google discovered that at least 20 other large companies from a wide range of businesses had been targeted in a similar way [193].
This series of cyberattacks came to be known as Operation Aurora [193] and were attributed to APT groups based in China. The name was coined by McAfee Labs security researchers based on their discovery that the word Aurora could be found in a file on the attacker’s machine that was later included in malicious binaries used in the attack as part of a file path. Typically, such a file path is inserted by the compiler into the binary to indicate where debug symbols and source code can be found on the developer’s machine. McAfee Labs therefore hypothesized that Aurora could be the name of the operation used by the attackers [179].
According to McAfee, the main target of the attack was source code repositories at high-tech, security, and defense contractor companies. If these repositories were modified in a malicious way, the attack could be spread further to their client companies. Operation Aurora can therefore be considered the first major attack on software supply chains [193].
In response to Aurora, Google shut down its operations in China four months after the incident and migrated away from a purely perimeter-based defense principle. This means devices are not trusted by default anymore, even if they are located within a corporate LAN [198].
1.5.3 The Jeep hack
At the BlackHat 2015 conference, security researchers Charlie Miller and Chris Valasek demonstrated the first remote attack on an unaltered, factory passenger car [120]. In what later became known as the Jeep hack, the researchers demonstrated how the vehicle’s infotainment system, Uconnect, which has both remote connectivity as well as the capability to communicate with other electronic control units within the vehicle, can be used for remote attacks.
Specifically, while systematically examining the vehicle’s attack surface, the researchers discovered an open D-Bus over an IP port on Uconnect, which is essentially an inter-process communication and remote procedure call mechanism. The D-Bus service accessible via the open port allows anyone connected to the infotainment system to execute arbitrary code in an unauthenticated manner.
Miller and Valasek also discovered that the D-Bus port was bound to all network interfaces on the vulnerable Uconnect infotainment system and was therefore accessible remotely over the Sprint mobile network that Uconnect uses for telematics. By connecting to the Sprint network using a femtocell or simply a regular mobile phone, the researchers were able to send remote commands to the vehicle.
From that entry point, Miller and Valasek attacked a chip in the vehicle’s infotainment system by re-writing its firmware to be able to send arbitrary commands over the vehicle’s internal CAN communication network, effectively giving them the ability to completely take over the vehicle.
1.5.4 Commonalities
What do these examples have in common and how does it relate to cryptography? In a nutshell, these examples illustrate what happens in the absence of appropriate cryptography. In all three cases discussed, there was no mechanism in place to verify that the systems were talking to legitimate users and that the messages received were not manipulated while in transit.
In the Mirai example, anyone with knowledge of the IoT devices’ IP addresses would have been able to access their login page. This information can be easily collected by scanning the public internet with tools such as nmap. So the designers’ assumption that the users would change the default device password to a strong individual one was the only line of defense. What the security engineers should have done instead is to add a cryptographic mechanism to give access to the login procedure only to legitimate users, for example, users in possession of a digital certificate or a private key.
In the case of Operation Aurora, the perimeter defense doctrine used by the affected companies treated every device within the trusted perimeter (typically, within a corporate network) as trustworthy by default. On this premise, every device inside the perimeter had access to all resources and systems within that perimeter.
As a result, anyone able to walk inside a company building or trick an arbitrary employee into clicking on a malicious link and infect their computer with malware would have been able to access all systems within the perimeter.
As a response to Operation Aurora, Google and other companies replaced perimeter defense with a zero trust security model that establishes trust by evaluating it on a per-transaction basis instead of basing trust on the network location (the perimeter) [155]. At the core of the zero trust security model is the ability to securely authenticate users and resources in order to prevent unauthorized access to data and services. Secure authentication, in turn, is built upon cryptography.
Finally, in the Jeep hack example, the open D-Bus over IP port allowed anyone connected to the vehicle’s infotainment system to execute arbitrary code in an unauthenticated manner. The possibility to access the vehicle remotely over the Sprint mobile network further increased the range of the attack. The system’s designers apparently assumed that the Sprint mobile network is a secure perimeter. What they should have done instead is to add a cryptographic mechanism to ensure that only legitimate users could log in to the Uconnect system.
