Detection of replay attacks in CPSs using observer-based signature compensation

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a replay attack detection method that addresses the performance loss of watermarking-based approaches. The proposed method injects a sinusoidal signal that affects a subset, chosen at random, of the system outputs. The presence of the signal in each one of the outputs is estimated by means of independent observers and its effect is compensated in the control loop. When a system output is affected by a replay attack, the loss of feedback of the associated observer destabilizes the signal estimation, leading to an exponential increase of the estimation error up to a threshold, above which the estimated signal compensation in the control loop is disabled. This event triggers the detection of a replay attack over the output corresponding to the disrupted observer. The effectiveness of the method is demonstrated using results obtained with a quadruple-tank system simulator.Peer ReviewedPostprint (author's final draft

Pakistan’s Nuclear Weapons Program and Implications for US National Security.

This article analyzes Pakistan’s nuclear weapons program and the characteristics of the environment in which the program is nested. These characteristics include Pakistan’s history of internal and external instability; nuclear saber rattling during crises; support for Islamic terrorism in order to advance state goals; indigenous production of many elements of its nuclear forces; possession of delivery and command and control systems with destabilizing characteristics; and finally, nuclear doctrine that appears to advocate first use of nuclear weapons. The article argues that the characteristics of Pakistan’s nuclear weapons program generate threats to US national security interests. The article examines six interrelated and synergistic challenges for US national security: first, Pakistan is engaged in an arms race in Southwest Asia that has negative implications for Pakistan’s stability; second, the threat of nuclear proliferation from Pakistan continues; third, Pakistan’s arsenal characteristics make accidental and/or unauthorized nuclear war more likely; fourth, there is an ongoing possibility of war with India; fifth, Islamist influence is spreading through key sectors of Pakistani society; and finally, there is an increasing danger of state failure in Pakistan

Security analysis of the micro transport protocol with a misbehaving receiver

BitTorrent is the most widely used Peer-to-Peer (P2P) protocol and it comprises the largest share of traffic in Europe. To make BitTorrent more Internet Service Provider (ISP) friendly, BitTorrent Inc. invented the Micro Transport Protocol (uTP). It is based on UDP with a novel congestion control called Low Extra Delay Background Transport (LEDBAT). This protocol assumes that the receiver always gives correct feedback, since otherwise this deteriorates throughput or yields to corrupted data. We show through experimental investigation that a misbehaving uTP receiver, which is not interested in data integrity, can increase the bandwidth of the sender by up to five times. This can cause a congestion collapse and steal large share of a victim’s bandwidth. We present three attacks, which increase the bandwidth usage significantly. We have tested these attacks in a real world environment and show its severity both in terms of number of packets and total traffic generated. We also present a countermeasure for protecting against the attacks and evaluate the performance of that defence strategy