Module006SystemHacking Flashcards
(184 cards)
Disctionary attack is applicable under two situations
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Methods to improve the success of a dictionary attack
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What is cryptanalysis
Cryptanalysis is a brute-force attack on an encryption employing a search of the keyspace.
What is Brute Force attack
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What is Rule based attack
Attackers use this type of attack when they obtain some information about the password. This is a more powerful attack than the dictionary and brute-force attacks, because the cracker knows the password type. For example, if the attacker knows that the password contains a two-or three-digit number, he or she will use some specific techniques to extract the password quickly.
What is Hybrid attack ?
Brute force + dictionary
Syllable Attack
Hackers use this cracking technique when passwords are not known words. Attackers use the dictionary and other methods to crack them, as well as all possible combinations of them.
Combination of brute force and dictionary attack
Password Guessing
The attacker creates a list of all possible passwords from the information collected through social engineering or any other way and tries them manually on the victim’s machine to crack the passwords
- Find a valid user
- Create a list of possible passwords
- Rank passwords from high probability to low
- Key in each password, until correct password is discovered
Manual Password-Cracking Algorithm
FOR loop thing
Default Passwords
- A default password is a password supplied by the manufacturer with new equipment (e.g. switches, hubs, routers) that is password protected
- Attackers use default passwords present in the list of words or dictionary that they use to perform password guessing attack
Active Online Attack: Trojan/Spyware/Keylogger
Attacker installs Trojan/Spyware/Keylogger on victim’s machine to collect victim’s user names and passwords Trojan/Spyware/Keylogger runs in the background and sends back all user credentials to the attacker
What is Trojan
A Trojan is a program that masks itself as a benign application. The software initially appears to perform a desirable or benign function but instead steals information or harms the system. With a Trojan, attackers can gain remote access and perform various operations limited by user privileges on the target computer.
What is Spyware
Spyware is a type of malware that attackers install on a computer to secretly gather information about its users without their knowledge. Spyware hides itself from the user and can be difficult to detect.
What is keylogger
A keylogger is a program that records all user keystrokes without the user’s knowledge. Keyloggers ship the log of user keystrokes to an attacker machine or hide it in the victim’s machine for later retrieval. The attacker then scrutinizes them carefully for finding passwords or other useful information that could compromise the system.
Active Online Attack Using USB Drive
- You need to download PassView, a password hacking tool.
- Copy the downloaded .exe PassView file to the USB drive.
- Create a Notepad document, and put the following content or code in the notepad: [autorun] en=launch.bat
After writing this content into Notepad, save the document as autorun.inf and copy this file to the USB drive.
- Open Notepad, and write the following content: start pspv.exe/stext pspv.txt After that, save file as launch.bat and copy this file to the USB drive.
- Insert the USB drive and the autorun window pop-up appears (if enabled).
- PassView (or other password-hacking tool) runs in the background and stores the passwords in the .txt files on the USB drive.
Active Online Attack: Hash Injection Attack
This type of attack is possible when the target system uses a hash function as part of the authentication process to authenticate its users. Generally, the system stores hash values of the credentials in the SAM database/file on a Windows computer. In such cases, the server computes the hash value of the user-submitted credentials or allows user to input the hash value directly. The server then checks it against the stored hash value for authentication. Attackers take advantage of such authentication mechanisms and first exploit the target server to retrieve the hashes from the SAM databases. They then input the hashes acquired directly into the authentication mechanism to authenticate with stolen user’s pre-computed hashes. Thus, in a hash injection attack, the attackers inject a compromised hash into a local session and then use the hash to authenticate to the network resources.
LLMNR, NBT-NS
LLMNR (Link Local Multicast Name Resolution) and NBT-NS (NetBIOS Name Service)
Active Online Attack: LLMNR/NBT-NS Poisoning
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LLMNR port
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NBT-NS port
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Steps in LLMNR/NBT-NS
- User sends a request to connect to the data sharing system, \DataServer which she mistakenly typed as \DtaServr.
- The \DataServer responds to the user saying that it does not know the host named \DtaServr.
- The user then performs LLMNR/NBT-NS broadcast to find out if anyone in the network knows the host name\DtaServr.
- The attacker replies to the user saying that it is \DataServer and accepts user NTLMv2 hash and responds to the user with an error.
LLMNR/NBT-NS Poisoning Tools
Responder.py
Passive Online Attack: Wire Sniffing
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Passive Online Attacks: Man-in-the-Middle and Replay Attack
In a MITM attack, the attacker acquires access to the communication channels between victim and server to extract the information.
In a replay attack, packets and authentication tokens are captured using a sniffer. After the relevant info is extracted, the tokens are placed back on the network to gain access.
Relatively hard to perpetrate
Must be trusted by one or both sides
Can sometimes be broken by invalidating traffic