Radiated electromagnetic emissions from video cables can leak information about the displayed image content to radio receivers in the vicinity. This confidentiality risk has long been demonstrated for analog video interfaces, such as VGA, as well as certain digital interfaces, such as DVI, HDMI, and the LVDS video connections often used inside devices with display panels. In all these cases, rasterizing amplitude-demodulated radio signals received in a quiet part of the spectrum can lead to recognizable screen content and readable text. However, DisplayPort, another commonly used computer video interface, has so far resisted such eavesdropping attacks. DisplayPort's significantly more complex signal structure and line encoding, and in particular its use of a linear-feedback shift register to scramble the bit stream, make its rasterized emissions appear like noise after amplitude demodulation. Here, we demonstrate more sophisticated video eavesdropping techniques for DisplayPort emissions, based on software-defined radio technology. These allow us to identify the video-mode parameters used by the target and synchronize the receiver with its timing structure, to then reconstruct not only readable text but also recognize different colours used. Our techniques work even if the receiver's bandwidth is an order of magnitude lower than the bitrate used on the video link.

Template attacks recover data values processed by tamper-resistant devices from side-channel waveforms, such as supply-current fluctuations (power analysis) or electromagnetic emissions. They first profile a device to generate multivariate statistics of the waveforms emitted for each of a set of known processed values, which then identify maximum-likelihood candidates of unknown processed values during an attack. We identify several practical obstacles arising in the implementation of template attacks, ranging from numerical errors to the incompatibility of templates across different devices, and propose and compare several solutions. We identify pooled covariance matrices and prior dimensionality reduction through Fisher's linear discriminant analysis as particularly efficient and effective, especially where many attack traces can be acquired. We evaluate alternative algorithms not only for the task of recovering key bytes from a hardware implementation of the Advanced Encryption Standard; we even reconstruct the value transferred by an individual byte-load instruction, with success rates reaching 85% (or a guessing entropy of less than a quarter bit remaining) after 1000 attack traces, thereby demonstrating direct eavesdropping of eight-bit parallel data lines. Using different devices during the profiling and attack phase can substantially reduce the effectiveness of template attacks. We demonstrate that the same problem can also occur across different measurement campaigns with the same device and that DC offsets (e.g., due to temperature drift) are a significant cause. We improve the portability of template parameters across devices by manipulating the DC content of the eigenvectors that form the projection matrix used for dimensionality reduction of the waveforms.

Cryptographic distance-bounding protocols verify the proximity of two parties by timing a challenge-response exchange. Such protocols rely on the underlying communication channel for accurate and fraud-resistant round- trip-time measurements, therefore the channel's exact timing properties and low-level implementation details become security critical. We practically implement 'late-commit' attacks, against two commercial radio receivers used in RFID and sensor networks, that exploit the latency in the modulation and decoding stages. These allow the attacker to extend the distance to the verifier by several kilometers. We also discuss how 'overclocking' a receiver can make a prover respond early. We practically implement this attack against an ISO 14443A RFID token and manage to get a response 10 µs earlier than normal. We conclude that conventional RF channels can be problematic for secure distance-bounding implementations and discuss the merits and weaknesses of special distance-bounding channels that have been proposed for RFID applications.

Radio-frequency identification tokens, such as contactless smartcards, are vulnerable to relay attacks if they are used for proximity authentication. Attackers can circumvent the limited range of the radio channel using transponders that forward exchanged signals over larger distances. Cryptographic distance-bounding protocols that measure accurately the round-trip delay of the radio signal provide a possible countermeasure. They infer an upper bound for the distance between the reader and the token from the fact that no information can propagate faster than at the speed of light. We propose a new distance-bounding protocol based on ultra-wideband pulse communication. Aimed at being implementable using only simple, asynchronous, low-power hardware in the token, it is particularly well suited for use in passive low-cost tokens, noisy environments and high-speed applications.

A new eavesdropping technique can be used to read cathode-ray tube (CRT) displays at a distance. The intensity of the light emitted by a raster-scan screen as a function of time corresponds to the video signal convolved with the impulse response of the phosphors. Experiments with a typical personal computer color monitor show that enough high-frequency content remains in the emitted light to permit the reconstruction of readable text by deconvolving the signal received with a fast photosensor These optical compromising emanations can be received even after diffuse reflection from a wall. Shot noise from background light is the critical performance factor In a sufficiently dark environment and with a large enough sensor aperture, practically significant reception distances are possible. This information security risk should be considered in applications with high confidentiality requirements, especially in those that already require "TEMPEST"-shielded equipment designed to minimize radio-frequency emission-security concerns.

Information-hiding techniques have recently become important in a number of application areas. Digital audio, video, and pictures are increasingly furnished with distinguishing but imperceptible marks, which may contain a hidden copyright notice or serial number or even help to prevent unauthorized copying directly. Military communications systems make increasing use of traffic security techniques which, rather than merely concealing the content of a message using encryption, seek to conceal its sender, its receiver, or its very existence. Similar techniques are used in some mobile phone systems and schemes proposed for digital elections. Criminals try to use whatever traffic security properties are provided intentionally or otherwise in the available communications systems, and police forces try to restrict their use. However, many of the techniques proposed in this young and rapidly evolving field can trace their history back to antiquity, and many of them are surprisingly easy to circumvent. In this article, we try to give an overview of the field, of what we know, what works, what does not, and what are the interesting topics for research.

A widely used bus-encryption microprocessor is vulnerable to a new practical attack. This type of processor decrypts on-the-fly while fetching code and data, which are stored in RAM only in encrypted form. The attack allows easy, unauthorized access to the decrypted memory content.

We consider the problem of distributing potentially dangerous information to a number of competing parties. As a prime example, we focus on the issue of distributing security patches to software. These patches implicitly contain vulnerability information that may be abused to jeopardize the security of other systems. When a vendor supplies a binary program patch, different users may receive it at different times. The differential application times of the patch create a window of vulnerability until all users have installed the patch. An abuser might analyze the binary patch before others install it. Armed with this information, he might be able to abuse another user's machine. A related situation occurs in the deployment of security tools. However, many tools will necessarily encode vulnerability information or explicit information about security “localisms”. This information may be reverse-engineered and used against systems. We discuss several ways in which security patches and tools may be made safer. Among these are: customizing patches to apply to only one machine; disguising patches to hinder their interpretation; synchronizing patch distribution to shrink the window of vulnerability; applying patches automatically; and using cryptoprocessors with enciphered operating systems. We conclude with some observations on the utility and effectiveness of these methods

The paper analyzes a network based denial of service attack for IP (Internet Protocol) based networks. It is popularly called SYN flooding. It works by an attacker sending many TCP (Transmission Control Protocol) connection requests with spoofed source addresses to a victim's machine. Each request causes the targeted host to instantiate data structures out of a limited pool of resources. Once the target host's resources are exhausted, no more incoming TCP connections can be established, thus denying further legitimate access. The paper contributes a detailed analysis of the SYN flooding attack and a discussion of existing and proposed countermeasures. Furthermore, we introduce a new solution approach, explain its design, and evaluate its performance. Our approach offers protection against SYN flooding for all hosts connected to the same local area network, independent of their operating system or networking stack implementation. It is highly portable, configurable, extensible, and requires neither special hardware, nor modifications in routers or protected end systems.