Computer security (794212), страница 3

Просмтор этого файла доступен только зарегистрированным пользователям. Но у нас супер быстрая регистрация: достаточно только электронной почты!

Текст из файла (страница 3)

In commercial environments, the majority of software subversion vulnerabilities result from a few known kinds of coding defects. Common software defects include buffer overflows, format string vulnerabilities, integer overflow, code or command injection and dangling pointers, which until recently was known but considered to be academic and not practically exploitable. These defects can be used to cause the target system to execute putative data. However, the data contain executable instructions, allowing the attacker to gain control of the processor.

Some common languages such as C and C++ are vulnerable to all of these. Other languages, such as Java, are more resistant to some of these defects, but are still prone to code or command injection and other software defects which facilitate subversion.

Unfortunately, there is no theoretical model of secure coding practices, nor is one practically achievable, insofar as the code (ideally, read-only) and data (generally read/write) generally tends to have some form of defect.

Capabilities and access control list

Within computer systems, two security models capable of enforcing privilege separation are access control lists (ACLs) and capability-based security. The semantics of ACLs have been proven to be insecure in many situations, for example, the confused deputy problem. It has also been shown that the promise of ACLs of giving access to an object to only one person can never be guaranteed in practice. Both of these problems are resolved by capabilities. This does not mean practical flaws exist in all ACL-based systems, but only that the designers of certain utilities must take responsibility to ensure that they do not introduce flaws.

Capabilities have been mostly restricted to research operating systems and commercial OSs still use ACLs. Capabilities can, however, also be implemented at the language level, leading to a style of programming that is essentially a refinement of standard object-oriented design. An open source project in the area is the E language.

The most secure computers are those not connected to the Internet and shielded from any interference. In the real world, the most secure systems are operating systems where security is not an add-on.

Hardware mechanisms that protects computers and data

Hardware based or assisted computer security offers an alternative to software-only computer security. Devices such as dongles, case intrusion detection, drive locks, or disabling USB ports, or CD ROM Drives may be considered more secure due to the physical access required in order to be compromised.

Network security

Network security is one of the orientations in computer security.

Network security covers a variety of computer networks, both public and private, that are used in everyday jobs conducting transactions and communications among businesses, government agencies and individuals. Networks can be private, such as within a company, and others which might be open to public access. Network security is involved in organizations, enterprises, and other types of institutions. It does as its title explains. It secures the network, as well as protecting and overseeing operations being done.

Network security concepts

Network security starts with authenticating, commonly with a username and a password. Since this requires just one detail authenticating the user name — i.e. the password — this is sometimes termed one-factor authentication. With two-factor authentication, something the user “has” is also used (e.g. a security token, an ATM card, or a mobile phone), and with three-factor authentication, something the user “is” is also used (e.g. a fingerprint or retinal scan).

Once authenticated, a firewall enforces access policies such as what services are allowed to be accessed by the network users. Though effective to prevent unauthorized access, this component may fail to check potentially harmful content such as computer worms or trojans being transmitted over the network. Anti-virus software or an intrusion prevention system (IPS) helps detect and inhibit the action of such malware. An anomaly-based intrusion detection system may also monitor the network and traffic for unexpected (or suspicious) content or behavior and other anomalies to protect resources, e.g. from denial of service attacks or an employee accessing files at strange times. Individual events occurring on the network may be logged for audit purposes and for later high-level analysis.

Communication between two hosts using a network may be encrypted to maintain privacy.

Honeypots, essentially decoy network-accessible resources, may be deployed in a network as surveillance and early-warning tools, as the honeypots are not normally accessed for legitimate purposes. Techniques used by the attackers that attempt to compromise these decoy resources are studied during and after an attack to keep an eye on new exploitation techniques. Such analysis may be used to further tighten security of the actual network being protected by the honeypot.

Security management

Security management for networks is different for all kinds of situations. A home or small office may only require basic security while large businesses may require high-maintenance and advanced software and hardware to prevent malicious attacks from hacking and spamming.

Homes and small businesses security requirements:

1. A basic firewall or a unified threat management system.

2. For Windows users, basic Antivirus software. An anti-spyware program would also be a good idea. There are many other types of antivirus or anti-spyware programs available.

3. When using a wireless connection, use a robust password. Also try to use the strongest security supported by your wireless devices, such as WPA2 with AES. TKIP may be more widely supported by your devices and should only be considered in cases where they are not compliant with AES.

4. If you are using wireless network, change the default SSID network name, also disable SSID Broadcast, because this function is unnecessary for home use. Security experts consider this to be easily bypassed with modern technology and some knowledge of how wireless traffic is detected by software.

5. Enable MAC Address filtering to keep track of all home network MAC devices connecting to your router. This is not a security feature per se, however it can be used to limit and strictly monitor your DHCP address pool for unwanted intruders.

6. Assign “static” IP addresses to network devices. This measure may be used, in conjunction with other features, to make your AP less desirable to would-be intruders.

7. Disable ICMP ping on router.

8. Review router or firewall logs to help identify abnormal network connections or traffic through your router.

9. Use passwords for all accounts.

10. If you use windows operating system, have multiple accounts per family member and use non-administrative accounts for day-to-day activities.

11. Raise awareness about information security to children.

Medium businesses security requirements:

1. A fairly strong firewall or Unified Threat Management System.

2. Strong antivirus software and internet security software.

3. Use strong passwords for authentication and change them on a weekly or monthly basis.

4. Using a wireless connection, use a robust password.

5. Raise awareness about physical security to employees.

6. Use an optional network analyzer or network monitor.

7. An enlightened administrator or manager.

8. Use a VPN (Virtual Private Network), to communicate between a main office and satellite offices using the Internet as a connectivity medium. A VPN offers a solution to the expense of leasing a data line while providing a secure network for the offices to communicate. Although the Internet is used, it is private because the link is encrypted and convenient to use. A medium sized business needing a secure way to connect several offices will find this a good choice.

9. Clear employee guidelines should be implemented for using the Internet, including access to non-work related websites, sending and receiving information.

10. Individual accounts to log on and access company intranet and Internet with monitoring for accountability.

11. Have a back-up policy to recover data in the event of a hardware failure or a security breach that changes, damages or deletes data.

12. Disabling messenger also helps to improve business security.

13. Assign several employees to monitor a group like CERT which studies Internet security vulnerabilities and develops training to help improve security.

Large businesses security requirements:

1. A strong firewall and proxy, or network Guard, to keep unwanted people out.

2. A strong antivirus software package and internet security software package.

3. For authentication, use strong passwords and change them on a weekly basis.

4. Using a wireless connection, use a robust password.

5. Exercise physical security precautions to employees.

6. Prepare a network analyzer or network monitor and use it when needed.

7. Implement physical security management like closed circuit television for entry areas and restricted zones.

8. Security fencing to mark the company's perimeter.

9. Fire extinguishers for fire-sensitive areas like server rooms and security rooms.

10. Security guards can help to maximize physical security.

School security requirements:

1. An adjustable firewall and proxy to allow authorized users access from the outside and inside.

2. Strong Antivirus software and Internet Security Software packages.

3. Wireless connections that lead to firewalls.

4. Supervision of network to guarantee updates and changes based on popular site usage.

5. Constant supervision by teachers, librarians, and administrators to guarantee protection against attacks from internet sources.

6. An enforceable and easy to understand acceptable use policy which differentiates between school owned and personally owned devices.

Large government security requirements:

1. A strong firewall and proxy to keep unwanted people out.

2. Strong antivirus software and internet security software suites.

3. Strong encryption of all information.

4. White list authorized wireless connection, block all else.

5. All network hardware is in secure zones.

6. All hosts should be on a private network that is invisible from the outside.

7. Host web servers in a DMZ, or a firewall from the outside and from the inside.

8. Security fencing to mark perimeter and set wireless range to this.

9. Inventory controls of government owned mobiles.

Hackers classification

Several subgroups of the computer underground with different attitudes use different terms to demarcate themselves from each other, or try to exclude some specific group with which they do not agree. According to (Clifford R.D. 2006) a cracker or cracking is to “gain unauthorized access to a computer in order to commit another crime such as destroying information contained in that system”. These subgroups may also be defined by the legal status of their activities.

White hat

A white hat hacker breaks security for non-malicious reasons, perhaps to test their own security system or while working for a security company which makes security software. The term “white hat” in Internet slang refers to an ethical hacker. This classification also includes individuals who perform penetration tests and vulnerability assessments within a contractual agreement. The EC-Council, also known as the International Council of Electronic Commerce Consultants, is one of those organizations that have developed certifications, courseware, classes, and online training covering the diverse arena of Ethical Hacking.

Black hat

A “black hat” hacker is a hacker who “violates computer security for little reason beyond maliciousness or for personal gain”. Black hat hackers form the stereotypical, illegal hacking groups often portrayed in popular culture, and are “the epitome of all that the public fears in a computer criminal”. Black hat hackers break into secure networks to destroy data or make the network unusable for those who are authorized to use the network. They choose their targets using a two-pronged process known as the “pre-hacking stage”.

Grey hat

A grey hat hacker is a combination of a Black Hat and a White Hat Hacker. A Grey Hat Hacker may surf the internet and hack into a computer system for the sole purpose of notifying the administrator that their system has been hacked, for example. Then they may offer to repair their system for a small fee.

Elite hacker

Характеристики

Список файлов реферата