ေဒါက္တာဖိုးလမ္း

ေဒါက္တာဖိုးလမ္း

This is our final free chapter in this smart contract hacking series, hopefully you enjoyed it, I am not sure what I am going to work on next, perhaps some malware analysis, reverse engineering or maybe some hacking in the cloud.

We are currently in 4th quarter and slammed with work so I wouldn't expect any more posts or the full blockchain release till after that eases up.

If you have any questions or comments you can hit us up at:

@ficti0n
http://cclabs.io

Cryptographic Implementations and Predictable PRNGs

Within operations that require random values we generally need a form of randomness coupled with our algorithm. If we do not have sufficient randomness and large character sets, we would end up with cryptographic collisions or predictable values depending what we are doing. This Is often the case in video game operations and data security encryption schemes. For example, we do not want to create random values which are predictable and repeatable based on known values or controllable values. With controllable values an attacker could duplicate the value by reverse engineering how it was originally created and what that random seed is. Also, If the value is predictable within a game, we may be able to cheat the game by creating our own valid values that exploit the perceived randomness.

Now we are not going to deep dive into cracking cryptography or brute forcing hash values. First off it takes too much time and effort. Secondly because there are easier more efficient ways of tackling cryptographic issues. Lastly, we do not have time for rabbit holes in a week-long penetration test that require us to explore many other attack vectors. Wasting a whole week on cracking a single cryptographic issue would be a terrible and inefficient penetration test leaving the rest of the target vulnerable. This may be suitable for R&D or a CTF but not for a penetration test.

What you need to understand is that certain functions often used as randomness on the blockchain is not suitable as a source of randomness. Additionally, understanding how things are implemented will get you much farther when it comes to cryptography then attacking it directly. You do not need to break NSA level encryption by attacking it directly. Instead you should concentrate on finding insecure implementations of these algorithms to get what you need.

Oracle padding attacks are a great example of this if you were in the hacking community back in the late 2000s. The padding attack relied on error messages based on padding within blocks to determine a way to decrypt them. This was a brilliant attack vector as you didn't need to understand deep cryptographic concepts to decrypt data blocks only how blocks work and how it was implemented. With this knowledge you could leverage the flawed implementation to get the decrypted values.

On the blockchain there are a number of insecure functionality that developers like to use when implementing random values. Most of these are very bad ideas for reasons we will discuss below.

For Example, the following non-exhaustive but often used list of values are not suitable for randomness within sensitive operations. Usage of these types of values for any sort of calculation is always suspect for closer review:

ü Secret keys in private variables

ü Block Timestamps
ü Block Numbers
ü Block Hash values

Why you ask? Well regardless of the data being set as private on the blockchain a private variable storage value is 100% readable on the blockchain. There are no secret values. These can be queried as you saw in the storage issues chapter. Also embedding hard coded values are certainly not private as they are in the source code which may be posted directly on the blockchain. Or could be reverse engineered out of the bytecode used to deploy the contract when the source code is not available. If you can get a hold of that value, then you can violate the security of that functionality.

Secondly do not rely on predictable values for randomness especially from block data sources. Block timestamps are controlled by miners which can aid in orchestrated attacks when used as a source of randomness. Also block numbers are easy to query and create predictable attacks when used in calculations, if internal functions are using a block number, they are all using the same PRNG. Finally, block hash values are terrible to use for randomness as only the last 256 block hash values on chain actually have a real value. Anything older than 256 is reduced to 0 meaning that every calculation will use the same value of 0. We will cover that in some of our examples.

This is not an exhaustive list but instead just a small portion of bad decisions for random values. There are plenty of other values which could be used within calculations as a random seed which are also predictable. It is always important to review the data used in these calculations when reviewing smart contract functionality. So, without the need of a PHD in cryptography you should easily discern that all of the above implementation examples are terrible for the inclusion of random data within cryptographic operations.

Simple BlockHash Example

Let's start out taking a look at a simple example of using a blockhash value with a blocknumber value. While a hash of a block might seem like a good idea as a random number there are numerous issues with it. Firstly, a blocknumber is a known value set by a miner that persists for a set length of time and can be queried and used in an attacker's similar algorithm to produce the same result and bypass controls. But there is also an underlying vulnerability to this approach when coupled with a blockchash which we will take a look at below.

Action Steps:

ü Open up your terminal and launch ganache-cli
ü Type out the code below into Remix
ü Within the Deploy Environment section dropdown change the JavaScript VM to the web3 Provider option.
ü Deploy the contract to ganache with the deploy button in Remix

1.    pragma solidity ^0.6.6;

2.

3.    contract simpleVulnerableBlockHash {

4.           uint32 public block_number;

5.           bytes32 public myHash;

6.

7.           function get_block_number() public  {

8.                   block_number = uint32(block.number);

9.           }

10.

11.  function set_hash() public{

12.                 myHash = bytes32(blockhash(block_number));

13.         }

14.

15.  function wasteTime() public{

16.                 uint test = uint(block.number);

17.  }

18. }

The simple contract above is querying for the current block number in the get_block_number function on line 8 and storing it within a block_number variable created on line 4. This is the current block number running on the blockchain.

Then we have a function on line 11 which takes the block number and uses it with the blockhash button to retrieve the blockhash and store it in the myHash variable.

BlockHash Vulnerability Walk and Talk:

Action Steps:

ü Execute the get_block_number function
ü Execute the set_hash function
ü Check the block_number value
ü Check the myHash value
ü Execute the wasteTime function 256 times
ü Execute the set_hash function
ü Check your myHash Value
ü What happened and what implications would this have on calculations your using this value with?

So, we have 2 variables of a block number and a block hash associated with that block number. What's the big deal. Well let's walk through this step by step and then play around with the remaining wasteTime function on line 15 to find out.

Starting out if we have the deployed contract and we execute the get_block_number function followed by the set_hash function we will get the following result when checking the block_number and myHash variables.

We see the blocknumber of 3 and then a hex value representing the block hash that starts with 0x995f. Now if we were to use this hash as a random value or within some algorithm to create a random value it might work depending what we were doing and the level of security required for the length of time we need it to be perceived as random for. It wouldn't be secure but maybe good enough for your operations. However, a blockhash has a dark little secret a developer may not be aware of. Block hashes in Ethereum have short term memory when it comes to blocks older than 256 from the current block.

So, what happens when we calculate a block after a time lapse? Let's give that a try by executing the wasteTime button till we reach block 259. Waste time sets a block value and discards it to enumerate blocks for us, it doesn't actually make any real changes. Normally blocks on the Ethereum network enumerate on their own every 30 seconds and we would simply just wait for 256 blocks, but we don't have traffic on our blockchain so we will enumerate it ourselves with wasteTime.

After we reach block 259 we execute the set_hash function again which will take block_number of 3 which is older than 256 blocks and get the hash. If you retrieve the myHash variable again after executing the set_hash function again it results in:

You will notice the myHash variable is now 0x000. because blocks older than 256 from the current block are not stored and result in a value of 0. Having a predictable value of 0 in our random algorithm can very likely create a situation where it would be easy to recreate the random number to bypass or cheat functionality in the smart contract.

Video Walkthrough of Bad Randomness:

A classical terrible example is something similar to this.

1.  Function checkWinner() public payable {

2.     If (blockhash(blockNumber) % 2 == 0) {

3.         Msg.sender.transfer(balance);

4.     }

5.  }

In the example above uses a blockhash function with a blockNumber variable within its calculation. The issue with this calculation is if that blockNumber variable is more than 256 blocks old it will return Zero and based on the calculation the user will win every single time.

All the attacker would need to do is play the game to create the blocknumber variable. Then the attacker would simply wait for 256 blocks to pass before checking if he has won the game. By doing this the attacker would guarantee a win.

In order to see how this would work let's take a look at a simple game of chance that implements this concept.

Action Steps:

ü Type out this code within remix
ü Deploy the code using Ganache and Web3 options
ü Try to locate the vulnerability within the code
ü Try to exploit the vulnerability this code so that you are always the winner

1.  pragma solidity ^0.6.6;

2.

3.  contract simpleVulnerableBlockHash {

4.

5.      uint balance = 2 ether;

6.      mapping (address => uint) blockNumber;

7.      bool public win;

8.

9.      constructor() public payable{

10.        require(msg.value >= 10 ether);

11.    }

12.

13.    function get_block_number() internal  {

14.        blockNumber[msg.sender] = uint(block.number);

15.    }

16.

17.    function playGame() public payable {

18.        require (msg.value >= 1 ether);

19.        get_block_number();

20.    }

21.

22.

23.    function checkWinner() public payable {

24.      if (uint(blockhash(blockNumber[msg.sender])) % 2 == 0) {

25.          win = true;

26.             msg.sender.transfer(balance);

27.      }   else{

28.             win = false;

29.         }

30.    }

31.

32.}

After trying to exploit this vulnerability yourself review the following video which walks you through the code and how to exploit it.

Video Walkthrough of Attacking The Game:

Preventing Randomness Summary

The best way to prevent these issues is to avoid on chain predictable values or secret values as your seed to operations and calculations. We can do this with trusted external Oracles. Oracles are external data sources that your contract can use when it needs random values or trusted data. There are projects that specifically solve this problem for example ChainLink which has networks of Oracle nodes that handle data queries and provide back trusted verified data including random numbers. A simple example for using Chainlink for a random number is found at the following link:

https://docs.chain.link/docs/get-a-random-number

It is always a good idea to avoid on chain secret data or block related information when performing any sort of sensitive operation and instead utilize an Oracle.

Bad Randomness References

https://docs.chain.link/docs/get-a-random-number

https://nvd.nist.gov/vuln/detail/CVE-2018-14715

https://github.com/cclabsInc/BlockChainExploitation/tree/master/2020_BlockchainFreeCourse/bad_randomness

What is the terminologies in ethical hacking?

Here are a few key terms that you will hear in discussion about hackers and what they do:

1-Backdoor-A secret pathway a hacker uses to gain entry to a computer system.

2-Adware-It is the softw-are designed to force pre-chosen ads to display on your system.

3-Attack-That action performs by a attacker on a system to gain unauthorized access.

4-Buffer Overflow-It is the process of attack where the hacker delivers malicious commands to a system by overrunning an application buffer.

5-Denial-of-Service attack (DOS)-A attack designed to cripple the victim's system by preventing it from handling its normal traffic,usally by flooding it with false traffic.

6-Email Warm-A virus-laden script or mini-program sent to an unsuspecting victim through a normal-looking email message.

7-Bruteforce Attack-It is an automated and simplest kind of method to gain access to a system or website. It tries different combination of usernames and passwords,again & again until it gets in from bruteforce dictionary.

8-Root Access-The highest level of access to a computer system,which can give them complete control over the system.

9-Root Kit-A set of tools used by an intruder to expand and disguise his control of the system.It is the stealthy type of software used for gain access to a computer system.

10-Session Hijacking- When a hacker is able to insert malicious data packets right into an actual data transmission over the internet connection.

11-Phreaker-Phreakers are considered the original computer hackers who break into the telephone network illegally, typically to make free longdistance phone calls or to tap lines.

12-Trojan Horse-It is a malicious program that tricks the computer user into opening it.There designed with an intention to destroy files,alter information,steal password or other information.

13-Virus-It is piece of code or malicious program which is capable of copying itself has a detrimental effect such as corrupting the system od destroying data. Antivirus is used to protect the system from viruses.

14-Worms-It is a self reflicating virus that does not alter files but resides in the active memory and duplicate itself.

15-Vulnerability-It is a weakness which allows a hacker to compromise the security of a computer or network system to gain unauthorized access.

16-Threat-A threat is a possible danger that can exploit an existing bug or vulnerability to comprise the security of a computer or network system. Threat is of two types-physical & non physical.

17-Cross-site Scripting-(XSS) It is a type of computer security vulnerability found in web application.It enables attacker to inject client side script into web pages viwed by other users.

18-Botnet-It is also known as Zombie Army is a group of computers controlled without their owner's knowledge.It is used to send spam or make denial of service attacks.

19-Bot- A bot is a program that automates an action so that it can be done repeatedly at a much higher rate for a period than a human operator could do it.Example-Sending HTTP, FTP oe Telnet at a higer rate or calling script to creat objects at a higher rate.

20-Firewall-It is a designed to keep unwanted intruder outside a computer system or network for safe communication b/w system and users on the inside of the firewall.

21-Spam-A spam is unsolicited email or junk email sent to a large numbers of receipients without their consent.

22-Zombie Drone-It is defined as a hi-jacked computer that is being used anonymously as a soldier or drone for malicious activity.ExDistributing Unwanted Spam Emails.

23-Logic Bomb-It is a type of virus upload in to a system that triggers a malicious action when certain conditions are met.The most common version is Time Bomb.

24-Shrink Wrap code-The process of attack for exploiting the holes in unpatched or poorly configured software.

25-Malware-It is an umbrella term used to refer a variety of intrusive software, including computer viruses,worms,Trojan Horses,Ransomeware,spyware,adware, scareware and other malicious program.

Follow me on instagram-anoymous_adi

Related word

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Update: Feb 19. 2015

We have been adding pcaps to the collection so remember to check out the folder ( Pcap collection) for the recent pcaps.

I had a project to test some malicious and exploit pcaps and collected a lot of them (almost 1000) from various public sources. You can see them in the PUBLIC folder. The credits go to the authors of the pcaps listed in the name of each file. Please visit their blogs and sites to see more information about the pcaps, see their recent posts, and send them thanks. The public pcaps have no passwords on them.

Update:Dec 13. 2014

Despite rare updates of this post, we have been adding pcaps to the collection so remember to check out the folder ( Pcap collection (New link)) for the recent pcaps!

Update:Dec 31. 2013 - added new pcaps

I did some spring cleaning yesterday and came up with these malware and exploit pcaps. Such pcaps are very useful for IDS and signature testing and development, general education, and malware identification. While there are some online public sandboxes offering pcaps for download like Cuckoo or Anubis but looking for them is a tedious task and you cannot be totally sure the pcap is for the malware family supposedly analysed - in other words, if the sandbox says it is Zeus does not necessarily mean that it is.

I found some good pcap repositories here (http://www.netresec.com/?page=PcapFiles) but there are very few pcaps from malware.

These are from identified and verified (to the best of my knowledge and belief - email me if you find errors) malware samples.

All of them show the first stage with the initial callback and most have the DNS requests as well. A few pcaps show extended malware runs (e.g. purplehaze pcap is over 500mb).
Most pcaps are mine, a few are from online sandboxes, and one is borrowed from malware.dontneedcoffee.com. That said, I can probably find the corresponding samples for all that have MD5 listed if you really need them. Search contagio, some are posted with the samples.

Each file has the following naming convention:
BIN [RTF, PDF] - the filetype of the dropper used, malware family name, MD5, and year+month of the malware analysis.

I will be adding more pcaps in the future. Please donate your pcaps from identified samples, I am sure many of you have.

Thank you

Download

Download all together or separately.

All pcaps archives have the same password (same scheme), email me if you need it. I tried posting it without any passwords and pass infected but they get flagged as malware. Modern AV rips though zips and zips with the pass 'infected' with ease.

APT PCAPS

Download all together or separately.

2012-12-31 BIN_Xinmic_8761F29AF1AE2D6FACD0AE5F487484A5-pcap
2013-09-08 BIN_TrojanPage_86893886C7CBC7310F7675F4EFDE0A29-pcap
2013-09-08 BIN_Darkcomet_DC98ABBA995771480AECF4769A88756E-pcap
2013-09-02 8202_tbd_ 6D2C12085F0018DAEB9C1A53E53FD4D1-pcap
2013-09-02 BIN_8202_6d2c12085f0018daeb9c1a53e53fd4d1-pcap
2013-09-02 BIN_Vidgrab_6fd868e68037040c94215566852230ab-pcap
2013-09-02 BIN_PlugX_2ff2d518313475a612f095dd863c8aea-pcap
2013-09-02 BIN_Taidoor_46ef9b0f1419e26f2f37d9d3495c499f-pcap
2013-09-02 BIN_Vidgrab_660709324acb88ef11f71782af28a1f0-pcap
2013-09-02 BIN_Gh0st-gif_f4d4076dff760eb92e4ae559c2dc4525-pcap.zip
2013-07-15 BIN_Taleret.E_5328cfcb46ef18ecf7ba0d21a7adc02c.pcap
2013-05-14 BIN_Mediana_0AE47E3261EA0A2DBCE471B28DFFE007_2012-10.pcap
2013-05-14 BIN_Hupigon_8F90057AB244BD8B612CD09F566EAC0C
2013-05-14 BIN_LetsGo_yahoosb_b21ba443726385c11802a8ad731771c0_2011-07-19
2013-05-13 BIN_IXESHE_0F88D9B0D237B5FCDC0F985A548254F2-2013-05-pcap
2013-05-06 BIN_DNSWatch_protux_4F8A44EF66384CCFAB737C8D7ADB4BB8_2012-11-pcap
2013-05-06 BIN_9002_D4ED654BCDA42576FDDFE03361608CAA_2013-01-30-pcap
2013-05-06 BIN_BIN_RssFeeder_68EE5FDA371E4AC48DAD7FCB2C94BAC7-2012-06-pcap (not a common name, see the traffic ssheet http://bit.ly/maltraffic )
2013-04-30 BIN_MSWab_Yayih_FD1BE09E499E8E380424B3835FC973A8_us-pcap
2013-04-29 BIN_LURK_AF4E8D4BE4481D0420CCF1C00792F484_20120-10-pcap
2013-04-29 BIN_XTremeRAT_DAEBFDED736903D234214ED4821EAF99_2013-04-13-pcap
BIN_Enfal_Lurid_0fb1b0833f723682346041d72ed112f9_2013-01.pcap
BIN_Gh0st_variant-v2010_B1D09374006E20FA795B2E70BF566C6D_2012-08.pcap
BIN_Likseput_E019E37F19040059AB5662563F06B609_2012-10.pcap
BIN_Nettravler_1f26e5f9b44c28b37b6cd13283838366.pcap
BIN_Nettravler_DA5832657877514306EDD211DEF61AFE_2012-10.pcap
BIN_Sanny-Daws_338D0B855421867732E05399A2D56670_2012-10.pcap
BIN_Sofacy_a2a188cbf74c1be52681f998f8e9b6b5_2012-10.pcap
BIN_Taidoor_40D79D1120638688AC7D9497CC819462_2012-10.pcap
BIN_TrojanCookies_840BD11343D140916F45223BA05ABACB_2012_01.pcap
PDF_CVE-2011-2462_Pdf_2011-12.pcap
RTF_Mongall_Dropper_Cve-2012-0158_C6F01A6AD70DA7A554D48BDBF7C7E065_2013-01.pcap
OSX_DocksterTrojan.pcap

CRIMEWARE PCAPS

Download all together or separately.

2013-11-12_BIN_ChePro_2A5E5D3C536DA346849750A4B8C8613A-1.pcap
2013-10-15_BIN_cryptolocker_9CBB128E8211A7CD00729C159815CB1C.pcap
2013-09-20_BIN_Lader-dlGameoverZeus_12cfe1caa12991102d79a366d3aa79e9.pcap
2013-09-08 BIN_Tijcont_845B0945D5FE0E0AAA16234DC21484E0-pcap
2013-09-08 BIN_Kelihos_C94DC5C9BB7B99658C275B7337C64B33-pcap.zip
2013-08-19 BIN_Nitedrem_508af8c499102ad2ebc1a83fdbcefecb-pcap
2013-08-17 BIN_sality_CEAF4D9E1F408299144E75D7F29C1810-pcap
2013-08-15 BIN_torpigminiloader-pcap.zip
2013-13-08 EK_popads_109.236.80.170_2013-08-13.pcap
2013-11-08 BIN_Alinav5.3_4C754150639AA3A86CA4D6B6342820BE.pcap
2013-08-08 BIN_BitcoinMiner_F865C199024105A2FFDF5FA98F391D74-pcap
2013-08-07 BIN_ZeroAccess_Sirefef_C2A9CCC8C6A6DF1CA1725F955F991940_2013-08-pcap
2013-07-05 BIN_Kuluoz-Asprox_9F842AD20C50AD1AAB41F20B321BF84B
2013-05-31 Wordpress-Mutopy_Symmi_20A6EBF61243B760DD65F897236B6AD3-2pcap.pcap
2013-05-15 BIN_Zeus_b1551c676a54e9127cd0e7ea283b92cc-2012-04.pcap
2013-05-15 BIN_Gypthoy_3EE49121300384FF3C82EB9A1F06F288-2013-05.pcap
2013-05-12 BIN_PassAlert_B4A1368515C6C39ACEF63A4BC368EDB2-2013-05-13
2013-05-12 BIN_HorstProxy_EFE5529D697174914938F4ABF115F762-2013-05-13-pcap
2013-05-12 BIN_Bitcoinminer_12E717293715939C5196E604591A97DF-2013-05-12-pcap
2013-05-07 BIN_ZeroAccess_Sirefef_29A35124ABEAD63CD8DB2BBB469CBC7A_2013-05-pcapc
2013-05-05 BIN_PowerLoader_4497A231DA9BD0EEA327DDEC4B31DA12_2013-05-pcap
2013-05-05 BIN_GameThief_ECBA0FEB36F9EF975EE96D1694C8164C_2013-03-pcap
2013-05-05 BIN_PowerLoader_4497A231DA9BD0EEA327DDEC4B31DA12_2013-05-pcap
2013-04-27 EK_BIN_Blackhole_leadingto_Medfos_0512E73000BCCCE5AFD2E9329972208A_2013-04-pcap
2013-04-26 -- BIN_Citadel_3D6046E1218FB525805E5D8FDC605361-2013-04-samp
BIN_CitadelPacked_2012-05.pcap
BIN_CitadelUnpacked_2012-05.pcap
BIN_Cutwail_284Fb18Fab33C93Bc69Ce392D08Fd250_2012-10.pcap
BIN_Darkmegi_2012-04.pcap
BIN_DarknessDDoS_v8g_F03Bc8Dcc090607F38Ffb3A36Ccacf48_2011-01.pcap-
BIN_dirtjumper_2011-10.pcap
BIN_DNSChanger_2011-12.pcap
BIN_Drowor_worm_0f015bb8e2f93fd7076f8d178df2450d_2013-04.pcap
BIN_Googledocs_macadocs_2012-12.pcap
BIN_Imaut_823e9bab188ad8cb30c14adc7e67066d.pcap
BIN_IRCbot_c6716a417f82ccedf0f860b735ac0187_2013-04.pcap
BIN_Kelihos_aka_Nap_0feaaa4adc31728e54b006ab9a7e6afa.pcap
BIN_LoadMoney_MailRu_dl_4e801b46068b31b82dac65885a58ed9e_2013-04 .pcap
BIN_purplehaze-2012-01.pcap
BIN_ponyloader_470a6f47de43eff307a02f53db134289.pcap
BIN_Ramnitpcap_2012-01.pcap
BIN_Reedum_0ca4f93a848cf01348336a8c6ff22daf_2013-03.pcap
BIN_SpyEye_2010-02.pcap
BIN_Stabuniq_F31B797831B36A4877AA0FD173A7A4A2_2012-12.pcap
BIN_Tbot_23AAB9C1C462F3FDFDDD98181E963230_2012-12.pcap
BIN_Tbot_2E1814CCCF0C3BB2CC32E0A0671C0891_2012-12.pcap
BIN_Tbot_5375FB5E867680FFB8E72D29DB9ABBD5_2012-12.pcap
BIN_Tbot_A0552D1BC1A4897141CFA56F75C04857_2012-12.pcap
BIN_Tbot_FC7C3E087789824F34A9309DA2388CE5_2012-12.pcap
BIN_Tinba_2012-06.pcap
BIN_Vobfus_634AA845F5B0B519B6D8A8670B994906_2012-12.pcap
BIN_Xpaj_2012-05.pcap
BIN_ZeroAccess_3169969E91F5FE5446909BBAB6E14D5D_2012-10.pcap
BIN_ZeusGameover_2012-02.pcap
BIN_Zeus_2010-12.pcap
EK_Blackholev1_2012-03.pcap
EK_Blackholev1_2012-08.pcap
EK_Blackholev2_2012-09.pcap
EK_Blackhole_Java_CVE-2012-4681_2012-08.pcap
EK_Phoenix_2012-04.pcap
EK_Smokekt150(Malwaredontneedcoffee)_2012-09.pcap - credit malware.dontneedcoffee.com

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Friday, May 26, 2023

Video Walkthrough of Bad Randomness:

Video Walkthrough of Attacking The Game:

Preventing Randomness Summary

Related links

Thursday, May 25, 2023

What is the terminologies in ethical hacking?

Here are a few key terms that you will hear in discussion about hackers and what they do:

1-Backdoor-A secret pathway a hacker uses to gain entry to a computer system.

2-Adware-It is the softw-are designed to force pre-chosen ads to display on your system.

3-Attack-That action performs by a attacker on a system to gain unauthorized access.

4-Buffer Overflow-It is the process of attack where the hacker delivers malicious commands to a system by overrunning an application buffer.

5-Denial-of-Service attack (DOS)-A attack designed to cripple the victim's system by preventing it from handling its normal traffic,usally by flooding it with false traffic.

6-Email Warm-A virus-laden script or mini-program sent to an unsuspecting victim through a normal-looking email message.

7-Bruteforce Attack-It is an automated and simplest kind of method to gain access to a system or website. It tries different combination of usernames and passwords,again & again until it gets in from bruteforce dictionary.

8-Root Access-The highest level of access to a computer system,which can give them complete control over the system.

9-Root Kit-A set of tools used by an intruder to expand and disguise his control of the system.It is the stealthy type of software used for gain access to a computer system.

10-Session Hijacking- When a hacker is able to insert malicious data packets right into an actual data transmission over the internet connection.

11-Phreaker-Phreakers are considered the original computer hackers who break into the telephone network illegally, typically to make free longdistance phone calls or to tap lines.

12-Trojan Horse-It is a malicious program that tricks the computer user into opening it.There designed with an intention to destroy files,alter information,steal password or other information.

13-Virus-It is piece of code or malicious program which is capable of copying itself has a detrimental effect such as corrupting the system od destroying data. Antivirus is used to protect the system from viruses.

14-Worms-It is a self reflicating virus that does not alter files but resides in the active memory and duplicate itself.

15-Vulnerability-It is a weakness which allows a hacker to compromise the security of a computer or network system to gain unauthorized access.

16-Threat-A threat is a possible danger that can exploit an existing bug or vulnerability to comprise the security of a computer or network system. Threat is of two types-physical & non physical.

17-Cross-site Scripting-(XSS) It is a type of computer security vulnerability found in web application.It enables attacker to inject client side script into web pages viwed by other users.

18-Botnet-It is also known as Zombie Army is a group of computers controlled without their owner's knowledge.It is used to send spam or make denial of service attacks.

19-Bot- A bot is a program that automates an action so that it can be done repeatedly at a much higher rate for a period than a human operator could do it.Example-Sending HTTP, FTP oe Telnet at a higer rate or calling script to creat objects at a higher rate.

20-Firewall-It is a designed to keep unwanted intruder outside a computer system or network for safe communication b/w system and users on the inside of the firewall.

21-Spam-A spam is unsolicited email or junk email sent to a large numbers of receipients without their consent.

22-Zombie Drone-It is defined as a hi-jacked computer that is being used anonymously as a soldier or drone for malicious activity.ExDistributing Unwanted Spam Emails.

23-Logic Bomb-It is a type of virus upload in to a system that triggers a malicious action when certain conditions are met.The most common version is Time Bomb.

24-Shrink Wrap code-The process of attack for exploiting the holes in unpatched or poorly configured software.

25-Malware-It is an umbrella term used to refer a variety of intrusive software, including computer viruses,worms,Trojan Horses,Ransomeware,spyware,adware, scareware and other malicious program.

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