Computer security compromised by hardware failure: Difference between revisions

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'''Computer security compromised by hardware failure''' is a branch of [[computer security]] applied to hardware.

The objective of computer security includes protection of information and property from theft, corruption, or [[natural disaster]], while allowing the information and property to remain accessible and productive to its intended users.<ref name="ComSec1">[[Computer security]]</ref> Such secret information could be retrieved by different ways. This article focus on the retrieval of data thanks to misused hardware or hardware failure. Hardware could be misused or exploited to get secret data. This article collects main types of attack that can be lead in ato data thieftheft.

Computer security can be comprised by devices, such as keyboards, monitors or printers (thanks to electromagnetic or acoustic emanation for example) or by components of the computer, such as the memory, the network card or the processor (thanks to time or temperature analysis for example).

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==== Electromagnetic emanations ====

Video display units radiate:

* narrowband harmonics of the digital clock signals ;

* broadband harmonics of the various 'random' digital signals such as the video signal.<ref name="Eck1">[[#Eck1|Eck, 1985, p.2]]</ref>

Known as compromising emanations or [[Tempest (codename)|TEMPEST]] radiation, a code word for a U.S. government programme aimed at attacking the problem, the electromagnetic broadcast of data has been a significant concern in sensitive computer applications. Eavesdroppers can reconstruct video screen content from radio frequency emanations.<ref name="Kuhn1">[[#Kuhn1|Kuhn,1998, p.1]]</ref> Each (radiated) harmonic of the video signal shows a remarkable resemblance to a broadcast TV signal. It is therefore possible to reconstruct the picture displayed on the video display unit from the radiated emission by means of a normal television receiver.<ref name="Eck1"/> If no preventive measures are taken, eavesdropping on a video display unit is possible at distances up to several hundreds of meters, using only a normal black-and-white TV receiver, a directional antenna and an antenna amplifier. It is even possible to pick up information from some types of video display units at a distance of over 1 kilometer. If more sophisticated receiving and decoding equipment is used, the maximum distance can be much greater.<ref name="Eck2">[[#Eck1|Eck, 1985, p.3]]</ref>

==== Compromising reflections ====

What is displayed by the monitor is reflected on the environment. The time-varying diffuse reflections of the light emitted by a CRT monitor can be exploited to recover the original monitor image.<ref name="[Back1]">[[#Back1|Backes, 2010, p.4]]</ref> This is an eavesdropping technique for spying at a distance on data that is displayed on an arbitrary computer screen, including the currently prevalent LCD monitors.

The technique exploits reflections of the screen’sscreen's optical emanations in various objects that one commonly finds in close proximity to the screen and uses those reflections to recover the original screen content. Such objects include eyeglasses, tea pots, spoons, plastic bottles, and even the eye of the user. This attack can be successfully mounted to spy on even small fonts using inexpensive, off-the-shelf equipment (less than 1500 dollars) from a distance of up to 10 meters. Relying on more expensive equipment allowed to conduct this attack from over 30 meters away, demonstrating that similar attacks are feasible from the other side of the street or from a close- by building.<ref name="[Back3]">[[#Back2|Backes, 2008, p.1]]</ref>

Many objects that may be found at a usual workplace can be exploited to retrieve information on a computer’scomputer's display by an outsider.<ref name="[Back4]">[[#Back2|Backes, 2008, p.4]]</ref> Particularly good results were obtained from reflections in a user’suser's eyeglasses or a tea pot located on the desk next to the screen. Reflections that stem from the eye of the user also provide good results. However, eyes are harder to spy on at a distance because they are fast-moving objects and require high exposure times. Using more expensive equipment with lower exposure times helps to remedy this problem.<ref name="[Back5]">[[#Back2|Backes, 2008, p.11]]</ref>

The reflections gathered from curved surfaces on close- by objects indeed pose a substantial threat to the confidentiality of data displayed on the screen. Fully invalidating this threat without at the same time hiding the screen from the legitimate user seems difficult, without using curtains on the windows or similar forms of strong optical shielding. Most users, however, will not be aware of this risk and may not be willing to close the curtains on a nice day.<ref name="[Back2]">[[#Back2|Backes, 2008, p.2]]</ref> The reflection of an object, a computer display, in a curved mirror creates a virtual image that is located behind the reflecting surface. For a flat mirror this virtual image has the same size and is located behind the mirror at the same distance as the original object. For curved mirrors, however, the situation is more complex.<ref name="[Back6]">[[#Back2|Backes, 2008, p.3]]</ref>

=== Keyboard ===

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The attack is very efficient, taking under 20 seconds per word on a standard PC. A 90% or better success rate of finding the correct word for words of 10 or more characters, and a success rate of 73% over all the words tested.<ref name="[Ber1]"/> In practice, a human attacker can typically determine if text is random. An attacker can also identify occasions when the user types user names and passwords.<ref name="[Zhu2]">[[#Zhu1|Zhuang, 2005, p.4]]</ref> Short audio signals containing a single word, with seven or more characters long was considered. This means that the signal is only a few seconds long. Such short words are often chosen as a password.<ref name="[Ber1]"/> The dominant factors affecting the attack's success are the word length, and more importantly, the number of repeated characters within the word.<ref name="[Ber1]"/>

This is a procedure that makes it possible to efficiently uncover a word out of audio recordings of keyboard click sounds.<ref name="[Ber3]">[[#Ber1|Berger, 2006, p.8]]</ref> More recently, extracting information out of an otheranother type of emanations was demonstrated: acoustic emanations from mechanical devices such as dot-matrix printers.<ref name="[Ber1]"/>

==== Video Eavesdropping on Keyboard ====

While extracting private information by watching somebody typing on a keyboard might seem to be an easy task, it becomes extremely challenging if it has to be automated. However, an automated tool is needed in the case of long-lasting surveillance procedures or long user activity, as a human being is able to reconstruct only a few characters per minute. The paper [[#Balz|"ClearShot: Eavesdropping on Keyboard Input from Video"]] presents a novel approach to automatically recovering the text being typed on a keyboard, based solely on a video of the user typing.<ref name="Balz1">[[#Balz1|Balzarotti, 2008, p.1]]</ref>

Automatically recognizing the keys being pressed by a user is a hard problem that requires sophisticated motion analysis. Experiments show that, for a human, reconstructing a few sentences requires lengthy hours of slow-motion analysis of the video.<ref name="Balz2">[[#Balz1|Balzarotti, 2008, p.2]]</ref> The attacker might install a surveillance device in the room of the victim, might take control of an existing camera by exploiting a vulnerability in the camera’scamera's control software, or might simply point a mobile phone with an integrated camera at the laptop’slaptop's keyboard when the victim is working in a public space.<ref name="Balz2"/>

Balzarotti's analysis is divided into two main phases (figure below).

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==== Acoustic emanations ====

With acoustic emanations, an attack that recovers what a dot-matrix printer processing English text is printing is possible. It is based on a record of the sound the printer makes, if the microphone is close enough to it. This attack recovers up to 72% of printed words, and up to 95% if knowledge about the text are done, with a microphone at a distance of 10&nbsp;cm from the printer.<ref name="[Back10]">[[#Back1|Backes, 2010, p.1]]</ref>

After an upfront training phase ("a" in the picture below), the attack ("b" in the picture below) is fully automated and uses a combination of machine learning, audio processing, and speech recognition techniques, including spectrum features, Hidden Markov Models and linear classification.<ref name="[Back1]"/> The fundamental reason why the reconstruction of the printed text works is that, the emitted sound becomes louder if more needles strike the paper at a given time.<ref name="[Back2]"/> There is a correlation between the number of needles and the intensity of the acoustic emanation.<ref name="[Back2]"/>

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[[Secure Shell|SSH]] is designed to provide a secure channel between two hosts. Despite the encryption and authentication mechanisms it uses, SSH has weaknesses. In interactive mode, every individual keystroke that a user types is sent to the remote machine in a separate IP packet immediately after the key is pressed, which leaks the inter-keystroke timing information of users’ typing. Below, the picture represents the command ''su'' processed through a SSH connection.

[[File:Ssh timingattack.png|500px|thumb|center||alt=|Network messages sent between the host and the client for the command 'su' – numbers are size of network packet in byte]]

A very simple statistical techniques suffice to reveal sensitive information such as the length of users’ passwords or even root passwords. By using advanced statistical techniques on timing information collected from the network, the eavesdropper can learn significant information about what users type in SSH sessions.<ref name="[Song1p1]">[[#Song1|Song, 2001, p.1]]</ref> Because the time it takes the operating system to send out the packet after the keypress is in general negligible comparing to the interkeystroke timing, this also enables an eavesdropper to learn the precise interkeystroke timings of users’ typing from the arrival times of packets.<ref name="[Song1p2]">[[#Song1|Song, 2001, p.2]]</ref>

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Data remanence problems not only affect obvious areas such as RAM and non-volatile memory cells but can also occur in other areas of the device through hot-carrier effects (which change the characteristics of the semiconductors in the device) and various other effects which are examined alongside the more obvious memory-cell remanence problems.<ref name="Gut1">[[#Gut1|Gutmann, 2001, p. 1]]</ref> It is possible to analyse and recover data from these cells and from semiconductor devices in general long after it should (in theory) have vanished.<ref name="Gut2">[[#Gut1|Gutmann, 2001, p. 4]]</ref>

Electromigration, which means to physically move the atom to new locations (to physically alter the device itself) is another type of attack.<ref name="Gut1" /> It involves the relocation of metal atoms due to high current densities, a phenomenon in which atoms are carried along by an "electron wind" in the opposite direction to the conventional current, producing voids at the negative electrode and hillocks and whiskers at the positive electrode. Void formation leads to a local increase in current density and Joule heating (the interaction of electrons and metal ions to produce thermal energy), producing further electromigration effects. When the external stress is removed, the disturbed system tends to relax back to its original equilibrium state, resulting in a backflow which heals some of the electromigration damage. In the long term though, this can cause device failure, but in less extreme cases it simply serves to alter a device’sdevice's operating characteristics in noticeable ways.

For example, the excavations of voids leads to increased wiring resistance and the growth of whiskers leads to contact formation and current leakage.<ref name="Gut10">[[#Gut1|Gutmann, 2001, p.5]]</ref> An example of a conductor which exhibits whisker growth due to electromigration is shown in the figure below:

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Contrary to popular assumption, DRAMs used in most modern computers retain their contents for several seconds after power is lost, even at room temperature and even if removed from a motherboard.<ref name="Hald1p1">[[#Hald1|Halderman, 2008, p1]]</ref>

Many products do cryptographic and other security-related computations using secret keys or other variables that the equipment’sequipment's operator must not be able to read out or alter. The usual solution is for the secret data to be kept in volatile memory inside a tamper-sensing enclosure. Security processors typically store secret key material in static RAM, from which power is removed if the device is tampered with. At temperatures below −20&nbsp;°C, the contents of SRAM can be ‘frozen’. It is interesting to know the period of time for which a static RAM device will retain data once the power has been removed. Low temperatures can increase the data retention time of SRAM to many seconds or even minutes.<ref name="Sko1p3">[[#Sko1|Skorobogatov, 2002, p.3]]</ref>

==== Read/Write exploits thanks to FireWire ====

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So, any device connected by FireWire can read and write data on the computer memory. For example, a device can :

* Grab the screen contents ;

* Just search the memory for strings such as login, passwords ;

* Scan for possible key material ;

* Search cryptographic keys stored in RAM ;

* Parse the whole physical memory to understand logical memory layout.

or

* Mess up the memory ;

* Change screen content ;

* Change UID/GID of a certain process ;

* Inject code into a process ;

* Inject an additional process.

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==== Cache attack ====

To increase the computational power, processors are generally equipped with a [[CPU cache|cache memory]] which decreases the memory access latency. Below, the figure shows the hierarchy between the processor and the memory. First the processor looks for data in the cache L1, then L2, then in the memory.

[[File:Mem cache.jpg|500px|thumb|center||alt=|Processor cache hierarchy]]

When the data is not where the processor is looking for, it is called a cache-miss. Below, pictures show how the processor fetch data when there are two cache levels.

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A simple and generic processor backdoor can be used by attackers as a means to privilege escalation to get to privileges equivalent to those of any given running operating system.<ref name="Dufl21">[[#Dufl2|Duflot, 2008, p.1]]</ref> Also, a non-privileged process of one of the non-privileged invited ___domain running on top of a virtual machine monitor can get to privileges equivalent to those of the virtual machine monitor.<ref name="Dufl21"/>

Loïc Duflot studied Intel processors in the paper "[[#Dufl2|CPU bugs, CPU backdoors and consequences on security]]" ; he explains that the processor defines four different privilege rings numbered from 0 (most privileged) to 3 (least privileged). Kernel code is usually running in ring 0, whereas user-space code is generally running in ring 3. The use of some security-critical assembly language instructions is restricted to ring 0 code. In order to escalate privilege through the backdoor, the attacker must :<ref name="Dufl22">[[#Dufl2|Duflot, 2008, p.5]]</ref>

# activate the backdoor by placing the CPU in the desired state ;

# inject code and run it in ring 0 ;

# get back to ring 3 in order to return the system to a stable state. Indeed, when code is running in ring 0, system calls do not work : Leaving the system in ring 0 and running a random system call (exit() typically) is likely to crash the system.

The backdoors Loïc Duflot presents are simple as they only modify the behavior of three assembly language instructions and have very simple and specific activation conditions, so that they are very unlikely to be accidentally activated. [[#Waks1|Recent inventions]] have begun to target these types of processor-based escalation attacks.

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=== Acoustic ===

* {{cite book| last1 = Asonov | first1 =D. | title =IEEE Symposium on Security and Privacy, 2004. Proceedings. 2004 | last2 = Agrawal | first2 = R. | periodical = Proceedings 2004 IEEE Symposium on Security and Privacy | volume = | pages = 3–11 | citeseerx = 10.1.1.89.8231 | year = 2004 | issn = 1081-6011 | doi = 10.1109/SECPRI.2004.1301311 | isbn = 978-0-7695-2136-37 | ref = Aso1 | chapter =Keyboard acoustic emanations | s2cid =216795 }}

* {{CitationCite conference | last1 = Zhuang | first1 = Li | last2 = Zhou | first2 = Feng | last3 = Tygar | first3 = J.D. | titlechapter = Keyboard acoustic emanations revisited | booktitletitle = ACM Transactions on Information and System Security (TISSEC) | periodicaljournal = ACM Transactions on Information Systems | conference = Proceedings of the 12th ACM Conference on Computer and Communications Security | place = Alexandria, Virginia, USA | volume = 13 | issue = 1 | pages = 373–382 | publisher = ACM New York, NY, USA | citeseerx = 10.1.1.117.5791 | year = 2005 | issn = 1094-9224 | doi = 10.1145/1609956.1609959 | isbn = 978-1-59593-226-76 | ref = Zhu1 }}

* {{cite book| last1 = Berger | first1 = Yigael | title = Proceedings of the 13th ACM conference on Computer and communications security – CCS '06 | last2 = Wool | first2 = Avishai | last3 = Yeredor | first3 = Arie | periodical = Proceedings of the 13th ACM conference on Computer and communications security | pages = 245–254 | place = Alexandria, Virginia, USA | citeseerx = 10.1.1.99.8028 | publisher = ACM New York, NY, USA | year = 2006 | doi = 10.1145/1180405.1180436 | isbn = 978-1-59593-518-52 | ref = Ber1| chapter = Dictionary attacks using keyboard acoustic emanations | s2cid = 2596394 }}

* {{Citation| last1 = Backes | first1 = Michael | last2 = Dürmuth | first2 = Markus | last3 = Gerling | first3 = Sebastian | last4 = Pinkal | first4 = Manfred | last5 = Sporleder | first5 = Caroline | title = Acoustic Side-Channel Attacks on Printers | periodical = Proceedings of the 19th [[USENIX]] Security Symposium | place = Washington, DC| url = http://www.usenix.org/events/sec10/tech/full_papers/Backes.pdf | year = 2010 | isbn = 978-1-931971-77-5 | ref = Back1 }}

=== Cache attack ===

* {{cite book| last1 = Osvik | first1 = Dag Arne | title = Topics in Cryptology – CT-RSA 2006 | last2 = Shamir | first2 = Adi | last3 = Tromer | first3 = Eran | booktitle = Lecture Notes in Computer Science | volume = 3860 | pages = 1–20 | periodical = Topics in Cryptology CT-RSA | publisher = Springer-Verlag Berlin, Heidelberg | place = San Jose, California, USA | citeseerx = 10.1.1.60.1857 | year = 2006 | issn = 0302-9743 | doi = 10.1007/11605805_1 | isbn = 978-3-540-31033-94 | ref = Sha1| chapter = Cache Attacks and Countermeasures: The Case of AES | series = Lecture Notes in Computer Science }}

* {{Citation| last1 = Page | first1 = Daniel | title = Partitioned cache architecture as a side-channel defence mechanism | periodical = Cryptology ePrint Archive | url = http://eprint.iacr.org/2005/280.pdf | year = 2005 | ref = Pag1 }}

* {{cite book| last1 = Bertoni | first1 = Guido | title = International Conference on Information Technology: Coding and Computing (ITCC'05) – Volume II | last2 = Zaccaria | first2 = Vittorio | last3 = Breveglieri | first3 = Luca | last4 = Monchiero | first4 = Matteo | last5 = Palermo | first5 = Gianluca | place = Washington, DC, USA | volume = 1 | pages = 586–591 | periodical = International Conference on Information Technology: Coding and Computing (ITCC'05) | publisher = IEEE Computer Society, Los Alamitos, California, USA | chapter-url = http://home.dei.polimi.it/gpalermo/papers/ITCC05.pdf | year = 2005 | doi = 10.1109/ITCC.2005.62 | isbn = 978-0-7695-2315-36 | ref = Bert1 | chapter = AES power attack based on induced cache miss and countermeasure | citeseerx = 10.1.1.452.3319 | s2cid = 9364961 }}

=== Chemical ===

* {{Citation | last1 = Gutmann | first1 = Peter | title = Data Remanence in Semiconductor Devices | volume = 10 | pages = 4 | periodical = Proceedings of the 10th conferenceConference on USENIX Security Symposium SSYM'01 | publisher = USENIX Association Berkeley, California, USA | url = http://www.cypherpunks.to/~peter/usenix01.pdf | year = 2001 | ref = Gut1 | access-date = 2010-12-13 | archive-url = https://web.archive.org/web/20070221201213/http://www.cypherpunks.to/~peter/usenix01.pdf | archive-date = 2007-02-21 | url-status = dead }}

=== Electromagnetic ===

* {{cite book| last1 = Kuhn | first1 = Markus G. | title = Information Hiding | volume = 1525 | last2 = Anderson | first2 = Ross J. | pages = 124–142 | periodical = Lecture Notes in Computer Science | url = http://www.springerlink.com/content/dm6kgf2p4mnrp0uv/ | year = 1998 | doi = 10.1007/3-540-49380-8_10 | isbn = 978-3-540-65386-48 | ref = Kuhn1| chapter = Soft Tempest: Hidden Data Transmission Using Electromagnetic Emanations | series = Lecture Notes in Computer Science | citeseerx = 10.1.1.64.6982 }}

* {{Citation| last1 = Van Eck | first1 = Wim | last2 = Laborato | first2 = Neher | title = Electromagnetic Radiation from Video Display Units: An Eavesdropping Risk? | volume = 4 | issue = 4 | pages = 269–286 | periodical = Computers & Security | url = http://portal.acm.org/citation.cfm?id=7308 | year = 1985 | doi = 10.1016/0167-4048(85)90046-X | isbnref = Eck1 | refciteseerx = Eck110.1.1.35.1695 }}

* {{cite book| last1 = Kuhn | first1 = Markus G. | title = Proceedings 2002 IEEE Symposium on Security and Privacy | pages = 3– | periodical = Proceedings of the 2002 IEEE Symposium on Security and Privacy |chapter-url=http://portal.acm.org/citation.cfm?id=829514.830537 | year = 2002 | doi = 10.1109/SECPRI.2002.1004358 | isbn = 978-0-7695-1543-64 | ref = Kuhn2| chapter = Optical time-___domain eavesdropping risks of CRT displays | citeseerx = 10.1.1.7.5870 | s2cid = 2385507 }}

* {{Citation| last1 = Vuagnoux | first1 = Martin | last2 = Pasini | first2 = Sylvain | title = Compromising electromagnetic emanations of wired and wireless keyboards | pages = 1–16 | periodical = In Proceedings of the 18th conferenceConference on USENIX securitySecurity symposiumSymposium (SSYM'09) | url = http://www.usenix.org/events/sec09/tech/full_papers/vuagnoux.pdf | year = 2009 | ref = Vuag1}}

* {{cite book| last1 = Backes | first1 = Michael | last2 = Dürmuth | first2 = Markus | last3 = Unruh | first3 = Dominique | title = CompromisingProceedings Reflections-or-How2002 toIEEE ReadSymposium LCDon MonitorsSecurity aroundand the CornerPrivacy | pages = 158–169 | periodicalyear = Proceedings of the IEEE Symposium on Security and Privacy2002 | place = Oakland, California, USA | chapter-url = http://crypto.m2ci.org/unruh/publications/reflections.pdf | year = 2008 | doi = 10.1109/SECPRI.2002.1004358 | isbn = 978-0-7695-3168-7 | ref = Back2| chapter = Optical time-___domain eavesdropping risks of CRT displays | citeseerx = 10.1.1.7.5870 | s2cid = 2385507 }}

=== FireWire ===

* {{Citation| last1 = Dornseif | first1 = Maximillian | title = 0wned by an iPod | pages = | periodical = PacSec | place = | url = http://pi1.informatik.uni-mannheim.de/filepool/publications/13.pdf | year = 2004 | doi = | isbn = | ref = Dorn1 }}

* {{Citation | last1 = Dornseif | first1 = Maximillian | title = FireWire all your memory are belong to us | pages = | periodical = CanSecWest | place = | url = http://md.hudora.de/presentations/firewire/2005-firewire-cansecwest.pdf | year = 2005 | doiref = Dorn2 | isbnaccess-date = 2010-12-17 | refarchive-url = Dorn2https://web.archive.org/web/20091229032404/http://md.hudora.de/presentations/firewire/2005-firewire-cansecwest.pdf | archive-date = 2009-12-29 | url-status = dead }}

=== Processor bug and backdoors ===

* {{cite book| last1 = Duflot | first1 = Loïc | title = Computer Security - ESORICS 2008 | volume = 5283| pages = 580–599 | periodical = ESORICS '08 Proceedings of the 13th European Symposium on Research in Computer Security: Computer Security | ___location = | url = http://www.springerlink.com/index/jp07870p24560678.pdf | year = 2008 | issn = | doi = 10.1007/978-3-540-88313-5_37 | isbn = 978-3-540-88312-8 | accessdate = | ref = Dufl2| chapter = CPU Bugs, CPU Backdoors and Consequences on Security | series = Lecture Notes in Computer Science }}

* {{Citation | last1 = Duflot | first1 = Loïc | title = Using CPU System Management Mode to Circumvent Operating System Security Functions | volume = | pages = 580–599 | periodical = Proceedings of CanSecWest | ___location = | url = http://www.ssi.gouv.fr/fr/sciences/fichiers/lti/cansecwest2006-duflot-paper.pdf | year = 2008 | issnref = Dufl3 | doiarchive-url = https://web.archive.org/web/20060526181027/http://www.ssi.gouv.fr/fr/sciences/fichiers/lti/cansecwest2006-duflot-paper.pdf | isbnarchive-date = 2006-05-26 | accessdateurl-status = |dead ref = Dufl3}}

* {{Citation | last1 = Waksman | first1 = Adam | title = Tamper Evident Microprocessors | volume = | pages = | periodical = Proceedings of the IEEE Symposium on Security and Privacy | ___location = Oakland, California | url = httphttps://www.cs.columbia.edu/~waksman/PDFs/Oakland_2010.pdf | year = 2010 | issnref = Waks1 | doiarchive-url = https://web.archive.org/web/20130921055451/https://www.cs.columbia.edu/~waksman/PDFs/Oakland_2010.pdf | isbnarchive-date = 2013-09-21 | accessdateurl-status = |dead ref = Waks1}}

=== Temperature ===

* {{Citation| last1 = Skorobogatov| first1 = Sergei | title = Low temperature data remanence in static RAM | journal = Technical Report - University of Cambridge. Computer Laboratory | publisher = University of Cambridge Computer Laboratory | place = Cambridge, UK| url = http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-536.pdf | year = 2002 | issn = 1476-2986 | ref = Sko1}}

* {{CitationCite book | last1 = Halderman | first1 = J. Alex | last2 = Schoen | first2 = Seth D. | last3 = Heninger | first3 = Nadia | author3-link = Nadia Heninger | last4 = Clarkson | first4 = William | last5 = Paul | first5 = William | last6 = Calandrino | first6 = Joseph A. | last7 = Feldman | first7 = Ariel J. | last8 = Appelbaum | first8 = Jacob | last9 = Felten | first9 = Edward W. | title = Lest Wewe Rememberremember: Cold-boot Boot Attacksattacks on Encryptionencryption Keyskeys | booktitle chapter= CommunicationsLest ofWe theRemember: ACMCold –Boot SecurityAttacks inon theEncryption BrowserKeys | volume = 52 | issue = 5 | pages = 45–60 | periodical = Proceedings of the USENIX Security Symposium | date = 2009 | publisher = ACM New York, New York, USA | url = http://citp.princeton.edu/pub/coldboot.pdf | year = 2008 | issn = 0001-0782 | doi = 10.1145/1506409.1506429 | isbn = 978-1-931971-60-7 | s2cid = 7770695 | ref = Hald1 | deadurlurl-status = yesdead | archiveurlarchive-url = https://web.archive.org/web/20110904213748/http://citp.princeton.edu/pub/coldboot.pdf | archivedatearchive-date = 2011-09-04 | df = }}

=== Timing attacks ===

* {{Citation| last1 = Song | first1 = Dawn Xiaodong | last2 = Wagner | first2 = David | last3 = Tian | first3 = Xuqing | title = Timing analysis of keystrokes and timing attacks on SSH | volume = 10 | pages = 337–352 | place = Washington, D.C., USA | periodical = Proceedings of the 10th conferenceConference on USENIX Security Symposium | publisher = USENIX Association Berkeley, California, USA | url = http://www.usenix.org/events/sec01/full_papers/song/song.pdf | year = 2001 | issn = | doi = | isbn = | ref = Song1}}

* {{cite book| last1 = Kocher | first1 = Paul C.| title = Advances in Cryptology – CRYPTO '96| volume = 1109 | pages = 104–113 | periodical = Proceedings of the 16th Annual International Cryptology Conference on Advances in Cryptology – CRYPTO '96 | series = Lecture Notes in Computer Science | publisher = Springer-Verlag, London, UK | place = Santa Barbara, California, USA | citeseerx = 10.1.1.40.5024 | year = 1996 | doi = 10.1007/3-540-68697-5_9 | isbn = 978-3-540-61512-15 | ref = Koch1| chapter = Timing Attacks on Implementations of Diffie-Hellman, RSA, DSS, and Other Systems| s2cid = 15475583}}

* {{Citation| last1 = Brumley | first1 = David | last2 = Boneh | first2 = Dan | title = Remote timing attacks are practical | volume = 12 | issue = 5 | pages = 701 | periodical = Proceedings of the 12th conferenceConference on USENIX Security Symposium SSYM'03 | publisher = USENIX Association Berkeley, California, USA | place = Washington, DC, USA | url = http://crypto.stanford.edu/~dabo/papers/ssl-timing.pdf | year = 2003 | doi = 10.1016/j.comnet.2005.01.010 | ref = Brum1| citeseerx = 10.1.1.12.2615 }}

=== Other ===

* {{cite book| last1 = Balzarotti | first1 = D.| title = 2008 IEEE Symposium on Security and Privacy (sp 2008)| last2 = Cova| first2 = M.| last3 = Vigna| first3 = G.| volume = | pages = 170–183 | periodical = Security and Privacy, 2008. SP 2008. IEEE Symposium on | ___location = Oakland, CA | url = http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4531152 | year = 2008 | issn = 1081-6011 | doi = 10.1109/SP.2008.28 | isbn = 978-0-7695-3168-7 | accessdate = | ref = Balz1| chapter = Clear ''Shot'': Eavesdropping on Keyboard Input from Video| citeseerx = 10.1.1.219.239| s2cid = 1498613}}

* {{Citation| language = fr | last1 = Duflot | first1 = Loïc | title = Contribution à la sécurité des systèmes d’exploitationd'exploitation et des microprocesseurs | volume = | pages = | periodical = | ___location = | url = http://www.ssi.gouv.fr/archive/fr/sciences/fichiers/lti/these-duflot.pdf | year = 2007 | issn = | doi = | isbn = | accessdate = | ref = Dufl1}}

{{Computer science}}

[[Category:Computer security]]