Archive for category Technology Research
While changes (fine-tuning) to a heuristic system often have unpredictable consequences, additions to URL filtering are absolutely predictable – it will block one spam campaign and nothing else. For example, consider a legitimate newsletter from drugstore.com (a legitimate retailer) that advertises various health products and perhaps has “free” offers. Many heuristic systems will have trouble accepting this as a legitimate email due to “spam-like” content. Because SpamStopsHere almost completely ignores normal content, this email would not be blocked.
Now consider a spammer that takes the drugstore.com newsletter and changes all URL links from drugstore.com to drugstorerx.com (assuming this is the spammer’s domain and website), and then sends this to a huge email list. This would be a heuristic system’s nightmare. First the spammer’s newsletter would likely not be blocked; then after many user reported the spam, the legitimate newsletter would also be blocked in the future.
With URL filtering, only the drugstorerx.com domain needs to be added to the blocking database. If not already in the blocking database, the SpamStopsHere technology would likely add it automatically and then have its 24/7 staff confirm it.
With URL filtering, the legitimate drugstore.com newsletter will never be blocked while the spammer’s newsletter (with nearly identical content) will be blocked 100%. Also, with URL filtering, the anti-spam vendor can determine precisely what will be blocked by policy. For example, the vendor can decide to block all emails that link to pornographic, casino and betting sites. Without blocking even vulgar personal emails, or discussions about casinos.
Advanced, built-in security protection and remote auditing help your organization comply with industry security standards, including Payment Card Industry Data Security Standard (PCI DSS), HIPAA, Basel II, and SOX, in a cost-effective way—without requiring multiple appliances, application changes, or rewrites. BIG-IP ASM reports previously unknown threats, such as layer 7 denial-of-service (DoS) and SQL injection attacks, and it mitigates web application threats to shield the organization from data breaches. All reports are GUI-driven and provide drill-down options with a click.
With PCI reporting, BIG-IP ASM lists security measures required by PCI DSS 1.2, determines if compliance is being met, and details steps required to become compliant if not.
Geolocation reporting informs you of the country where threats originate in addition to attack type, violation, URL, IP address, severity, and more. You can also schedule reports to be sent to a designated email address automatically for up-to-date reporting.
Easy-to-read format for remote auditing
BIG-IP ASM makes security compliance easier and saves valuable IT time by exporting policies in human readable format. The flat, readable XML file format enables auditors to view the policies off site. Auditors working remotely can view, select, review, and test policies without requiring time and support from the web application security administrator.
In this model, we assume OCF (OpenCard Framework) and the smartX engine are initially installed and configured on the target terminal. As explained in the previous section, the terminal application consists in two blocks: the application process and the application protocol. The application process that encapsulates the logic of the application is compiled into a Java applet signed by a trusted entity. The application protocol is described inside an SML dictionary and is card-specific. Once the Java applet is downloaded, the smartX engine identifies the smart card inserted in the terminal. A simple identification consists in verifying the historical bytes of the card ATR (Answer To Reset). After correct identification, the smartX engine dynamically downloads the SML dictionary that contains the application protocol for the card inserted inside the terminal. With this dynamic mechanism, you minimize the loading time since you only download the dictionary relevant to the card inside the terminal.
In the OCF model, you had to download with the applet all the CardService implementations. With smartX, a terminal is also not limited to a predefined set of smart cards. As long as you provide the correct SML dictionary, a terminal can dynamically accept a new smart card that was not originally supported by the application. All these advantages make smartX a platform of choice for developing and deploying smart card applications on the Internet.
Each shared resource has a priority ceiling that is defined as the priority of the highest-priority task that can ever access that shared resource. The protocol is defined as follows,
- A task runs at its original (sometimes called its base) priority when it is outside a critical section.
- A task can lock a shared resource only if its priority is strictly higher than the priority ceilings of all shared resources currently
locked by other tasks. Otherwise, the task must block, and the task which has locked the shared resource with the highest priority ceiling inherits the priority of task.
An interesting consequence of the above protocol is that a task may block trying to lock a shared resource, even though the resource is not locked. The priority ceiling protocol has the interesting and very useful property that no task can be blocked for longer than the duration of the longest critical section of any lower-priority task.
Priority Ceiling Protocol Emulation
The priority ceiling of a shared resource is defined, as before, to be the priority of the highest-priority task that can ever access that resource. A task executes at a priority equal to (or higher than) the priority ceiling of a shared resource as soon as it enters a critical section associated with that resource. Applying the Priority Ceiling Protocol Emulation to the Priority Ceiling Protocol example results in the following sequence:
In a virtual environment system a computer generates sensory impressions that are delivered to the human senses. The type and the quality of these impressions determine the level of immersion and the feeling of presence in VR. Ideally the high-resolution, high-quality and consistent over all the displays, information should be presented to all of the user’s senses. Moreover, the environment itself should react realistically to the user’s actions. The practice, however, is very different from this ideal case. Many applications stimulate only one or a few of the senses, very often with low-quality and unsynchronized information. We can group the VR systems accordingly to the level of immersion they offer to the user.
- Desktop VR – sometimes called Window on World (WoW) systems. This is the simplest type of virtual reality applications. It uses a conventional monitor to display the image (generally monoscopic) of the world. No other sensory output is supported.
- Fish Tank VR – improved version of Desktop VR. These systems support head tracking and therefore improve the feeling of “of being there” thanks to the motion parallax effect. They still use a conventional monitor (very often with LCD shutter glasses for stereoscopic viewing) but generally do not support sensory output.
- Immersive systems – the ultimate version of VR systems. They let the user totally immerse in computer generated world with the help of HMD that supports a stereoscopic view of the scene accordingly to the user’s position and orientation. These systems may be enhanced by audio, haptic and sensory interfaces.
In stateful page evaluation, the browser history file and additional history stored by SpoofGuard are used to evaluate the referring page. Since it is important to minimize the number of false alarms, SpoofGuard does not issue any warnings for visiting a site that is in the user’s history file. The rationale for this is that if the user is warned the first time, and decides to proceed, the user is assumed to have sufficient reason to trust the site.
Domain check : If the domain of a page closely resembles a standard or previously visited domain, the page may be part of a spoof. Although crude, we currently compare domains by Hamming (edit) distance. For example example.com will raise the domain check if example.com is in the file of commonly spoofed sites or in the user history. Clearly, it is possible to improve our comparison algorithm by studying the way people are fooled; this is a significant direction for future work.
A related issue is that some businesses outsource some of their web operations to contractors with different domain names. This poses an interesting challenge that we believe can be addressed. However, outsourced web activity leads to false alarms in the current version of
Referring page When a user follows a link, the browser maintains a record of the referring page. Since the typical web spoofing attack begins with an email message, a referring page from a web site where the user may have been reading email (such as Hotmail) raises
the level of suspicion. One complication associated with Hotmail, for example, is that Hotmail uses numeric IP addresses instead of symbolic host names. Therefore, when a user clicks on a link in a Hotmail message, the browser provides a numeric IP address to SpoofGuard as the referring page. In this situation, SpoofGuard uses reverse DNS to find the domain name associated with a numeric address, allowing us to identify Hotmail as the referring site.
Image-domain associations The image check described on database associating images such as corporate logos with domains.
The initial static database can be assembled using a web crawler or other tool, or it can be augmented using an individual’s browsing history. An early version of SpoofGuard used a fixed database; the current SpoofGuard implementation uses a hashed image history file.
Home Phoneline Networking Alliance (Home PNA) [HPNA] has standardized a technology which allows networking of devices using the existing telephone wiring of the home.
There is no need for a central control unit in the network, but each device is required to have a Home PNA adapter. Those come either in the form of PCI cards or Ethernet to Home PNA adapters, which allow connecting a standard Ethernet device to a Home PNA network, as shown in Figure 1.
Figure 1. Basic home networking with Home PNA
Home PNA Version 2.0 is designed to reach up to 300 meters between any two adapters. If the network has more than two Home PNA adapters, all of the adapters must be within 300 meters of each other. The actual distance may be longer or perhaps shorter depending on the type of wire, noise conditions and topology of the telephone wiring within the home. Theoretical maximum speed of the Home PNA technology is 10 Mbps, which is quite low compared to competing previously mentioned standards.
Video codecs use various compression techniques to fit a video signal into the allotted channel bandwidth. These compression
techniques can affect the resulting quality of the video in different ways. An understanding of encoding principles can help a
content provider determine what content will look best on a mobile device, and highlight some of the expected trade offs when
producing multimedia files.
Quick bandwidth reduction can be achieved by using video compression techniques such as:
- Removing statistical redundancies
- Reducing resolution size (for example, CIF ➔ QCIF)
- Using fewer frames per second (for example, 15 fps ➔ 10 fps)
Further bandwidth reduction can be achieved by leveraging the patterns within the video data and removing redundancies. Image
compression relies on discarding information that is indiscernible to the viewer. Motion compensation provides interpolation
between frames, using less data to represent the change. The goal of a video encoder is to remove redundancies in the video
stream and to encode as little data as possible. To achieve this goal, the encoder samples the video stream in two ways:
- In time intervals from consecutive frames (temporal domain)
- Between adjacent pixels in the same frame (spatial domain)
A video decoder pieces the video stream together by reversing the encoding process. The decoder reconstructs the video stream
by adding together the pixel differences and frame differences to form a complete video.
This is an overly simplified look at compression, but it is useful to remember that a compressed video stream provides the deltas
between previously encoded data, instead of a complete representation of each frame.