Embedded systems are responsible for the security and safety of modern societies, controlling the correct operation of cars and airplanes, satellites and medical equipment, military units and all critical infrastructures. Being integrated in large and complex environments, embedded systems need to support several communication protocols to interact with other devices or with their users. Interestingly, embedded software often implements protocols that deviate from their original specifications. Some are extended with additional features, while others are completely undocumented. Furthermore, embedded parsers often consist of complex C code which is optimized to improve performance and reduce size. However, this code is rarely designed with security in mind, and often lacks proper input validation, making those devices vulnerable to memory corruption attacks. Furthermore, most embedded designs are closed source and third party security evaluations are only possible by looking at the binary firmware.

IMSI catching is a problem on all generations of mobile telecommunication networks, i.e., 2G (GSM, GPRS), 3G (HDSPA, EDGE, UMTS) and 4G (LTE, LTE+). Currently, the SIM card of a mobile phone has to reveal its identity over an insecure plaintext transmission, before encryption is enabled. This identifier (the IMSI) can be intercepted by adversaries that mount a passive or active attack. Such identity exposure attacks are commonly referred to as 'IMSI catching'. Since the IMSI is uniquely identifying, unauthorized exposure can lead to various location privacy attacks. We propose a solution, which essentially replaces the IMSIs with changing pseudonyms that are only identifiable by the home network of the SIM's own network provider. Consequently, these pseudonyms are unlinkable by intermediate network providers and malicious adversaries, and therefore mitigate both passive and active attacks, which we also formally verified using ProVerif. Our solution is compatible with the current specifications of the mobile standards and therefore requires no change in the infrastructure or any of the already massively deployed network equipment. The proposed method only requires limited changes to the SIM and the authentication server, both of which are under control of the user's network provider. Therefore, any individual (virtual) provider that distributes SIM cards and controls its own authentication server can deploy a more privacy friendly mobile network that is resilient against IMSI catching attacks.

Despite a series of attacks, MIFARE Classic is still the world's most widely deployed contactless smartcard on the market. The Classic uses a proprietary stream cipher CRYPTO1 to provide confidentiality and mutual authentication between card and reader. However, once the cipher was reverse engineered, many serious vulnerabilities surfaced. A number of passive and active attacks were proposed that exploit these vulnerabilities. The most severe key recovery attacks only require wireless interaction with a card. System integrators consider such card-only attacks as one of the most serious threat vectors to their MIFARE Classic-based systems, since it allows the adversary to avoid camera detection, which is often present at an access control entrance or public transport gate. However, all card-only attacks proposed in the literature depend on implementation mistakes which can easily be mitigated without breaking backwards compatibility with the existing reader infrastructure. Consequently, many manufactures and system integrators started to deploy "fixed" MIFARE Classic cards which are resilient to such vulnerabilities. However, these countermeasures are rather palliating and inadequate for a cryptographically insecure cipher such as CRYPTO1. In support of this proposition, we present a novel cipher-text card-only attack that exploits a crucial and mandatory step in the authentication protocol and which solely depends on the cryptographic weaknesses of the CRYPTO1 cipher. Hence, in order to avoid this attack, all cards and readers should be upgraded to support an alternative authentication protocol which inherently breaks their backwards compatibility. Our attack requires only a few minutes of wireless interaction with the card, in an uncontrolled environment and can be performed with consumer-grade hardware. The information obtained allows an adversary to drop the computational complexity from 2^48 to approximately 2^30, which enabled us to practically recover a secret key from a hardened MIFARE Classic card in about 5 minutes on an single core consumer laptop.

The Atmel chip families SecureMemory, CryptoMemory, and CryptoRF use a proprietary stream cipher to guarantee authenticity, confidentiality, and integrity. This paper describes the cipher in detail and points out several weaknesses. One is the fact that the three components of the cipher operate largely independently; another is that the intermediate output generated by two of those components is strongly correlated with the generated keystream. For SecureMemory, a single eavesdropped trace is enough to recover the secret key with probability 0.57 in 2^{39} cipher ticks. This is a factor of 2^{31.5} faster than a brute force attack. On a 2 GHz laptop, this takes around 10 minutes. With more traces, the secret key can be recovered with virtual certainty without significant additional cost in time. For CryptoMemory and CryptoRF, if one has 2640 traces it is possible to recover the key in 2^{52} cipher ticks, which is 2^{19} times faster than brute force. On a 50 machine cluster of 2 GHz quad-core machines this would take less than 2 days.

The Mifare Classic is the most widely used contactless smartcard on the market. The stream cipher CRYPTO1 used by the classic has recently been reverse engineered and serious attacks have been proposed. The most serious of them retrieves a secret key in under a second. In order to clone a card, previously proposed attacks require that the adversary either has access to an eavesdropped communication session or executes a message-by-message man-in-the-middle attack between the victim and a legitimate reader. Although this is already disastrous from a cryptographic point of view, system integrators maintain that these attacks cannot be performed undetected.This paper proposes four attacks that can be executed by an adversary having only wireless access to just a card (and not to a legitimate reader). The most serious of them recovers a secret key in less than a second on ordinary hardware. Besides the cryptographic weaknesses, we exploit other weaknesses in the protocol stack. A vulnerability in the computation of parity bits allows an adversary to establish a side channel. Another vulnerability regarding nested authentications provides enough plaintext for a speedy known-plaintext attack.