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Malwares

⚡︎ This chapter has practical labs

- What is Malware?

Any software intentionally designed to cause damage to a computer, server or computer network. The code is described as computer viruses, worms, Trojan horses, ransomware, spyware, adware, and scareware, among other terms. Malware has a malicious intent, acting against the interest of the computer user.

Types of Viruses and Worms 🐛

  • How it works?
    1. Infection Phase - a virus planted on a target system and replicates itself and attaches to one or more executable files
    2. Attack phase - the infected file is executed accidentally by the user, or in some way is deployed and activated

  • Virus - Designed to spread from host to host and has the ability to replicate itself. They cannot reproduce/spread without help. They operate by inserting or attaching itself to a legitimate program or document in order to execute its code.

  • Macro Virus - Written in a macro language (e.g: VBA) and that is platform independent.

  • Compression Viruses - Another type of virus that appends itself to executables on the system and compresses them by user's permissions.

  • Stealth Virus - Hides the modifications it has made; Trick antivirus software; intercepting its requests to the OS and provides false and bogus information.

  • Polymorphic Virus - Produces varied but operational copies of itself. A polymorphic virus may have no parts that remain identifcal between infections, making it very hard to detect using signatures.

  • Multipart Virus - Attempts to infect both boot sector and files; generally refers to viruses with multiple infection methods

  • Self-garbling (metamorphic) virus - Rewrites itself every time it infects a new file.

  • Other Virus Types

    • Boot Sector Virus - known as system virus; moves boot sector to another location and then inserts its code int he original location
    • Shell Virus - wraps around an application's code, inserting itself before the application's
    • Cluster Virus - modifies directory table entries so every time a file or folder is opened, the virus runs
    • Encryption Virus - uses encryption to hide the code from antivirus
    • Cavity Virus - overwrite portions of host files as to not increase the actual size of the file; uses null content sections
    • Sparse Infector Virus - only infects occasionally (e.g. every 10th time)
    • File Extension Virus - changes the file extensions of files to take advantage of most people having them turned off (readme.txt.vbs shows as readme.txt)

  • Virus Makers

    • Sonic Bat
    • PoisonVirus Maker
    • Sam's Virus Generator
    • JPS Virus Maker

  • Worm - self-replicating malware that sends itself to other computers without human intervention

    • Usually doesn't infect files - just resides in active memory
    • Often used in botnets

  • Ghost Eye Worm - hacking tool that uses random messaging on Facebook and other sites to perform a host of malicious efforts.

  • Logic Bomb - Executes a program when a certain event happens or a date and time arrives.

  • Rootkit - Set of malicious tools that are loaded on a compromised system through stealthy techniques; Very hard to detect;

  • Ransomware - malicious software designed to deny access to a computer until a price is paid; usually spread through email

    • WannaCry - famous ransomware; within 24 hours had 230,000 victims; exploited unpatched SMB vulnerability
      • Other Examples
        • Cryptorbit
        • CryptoLocker
        • CryptoDefense
        • police-themed

  • Trojan horse - A program that is disguised as another legitimate program with the goal of carrying out malicious activities in the background without user's knowledge.

    • RAT - Remote Access Trojans - Malicious programs that run on systems and allow intruders to access and use a system remotely.

  • Immunizer - Attaches code to a file or application, which would fool a virus into 'thinking' it was already infected. (e.g: like human vaccine).

  • Behavior blocking - Allowing the suspicious code to execute within the OS and watches its interactions looking for suspicious activities.

️⚠️ - Viruses needs help/interaction to propagate; Worms self propagates

Major characteristics of viruses:

  1. Infecting other files
  2. Alteration of data
  3. Transforms itself
  4. Corruption of files and data
  5. Encrypts itself
  6. Self-replication

Stages of Virus Lifecycle:

  1. Design
  2. Replication
  3. Launch
  4. Detection
  5. Incorporation - A.V. figures out the virus pattern & builds signatures to identify and eliminate the virus
  6. Execution of the damage routine - A.V. to the rescue

Malware Basics

  • How is malware distributed?
    • SEO manipulation
    • Social Engineering / Click-jacking
    • Phishing
    • Malvertising
    • Compromising legitimate sites
    • Drive-by downloads
    • Spam

  • Malware - software designed to harm or secretly access a computer system without informed consent

    • Most is downloaded from the Internet with or without the user's knowledge

  • Overt Channels - legitimate communication channels used by programs

  • Covert Channels - used to transport data in unintended ways

  • Wrappers - programs that allow you to bind an executable to an innocent file

Basic components of Malware

  1. Crypters - use a combination of encryption and code manipulation to render malware undetectable to security programs; protects from being scanned or found during analysis.

  2. Downloader - Used to download additional malware.

  3. Dropper - Used to install additional malware into the target system.

  4. Exploit - Malicious code used to execute on a specific vulnerability.

  5. Injector - Used to expose vulnerable processes in the target system to the exploit.

  6. Obfuscator - Used to conceal the true purpose of the malware.

  7. Packers - Used to bundle all of the malware files together into a single executable.

  8. Payload - Used to take over the target machine.

  9. Malicious Code - Used to define the abilities of the malware.

Exploit Kits - help deliver exploits and payloads

  • Infinity
  • Bleeding Life
  • Crimepack
  • Blackhole Exploit Kit

Trojans 🐴

  • Software that appears to perform a desirable function but instead performs malicious activity

    • To hackers, it is a method to gain and maintain access to a system
    • Trojans are means of delivery whereas a backdoor provides the open access
    • Trojans are typically spread through Social Engineering.

  • Types of Trojans:

    • Defacement trojan
    • Proxy server trojan
    • Botnet trojan
      • Chewbacca
      • Skynet
    • Remote access trojans
      • RAT
      • MoSucker
      • Optix Pro
      • Blackhole
    • E-banking trojans
      • Zeus
      • Spyeye
    • IoT Trojans
    • Security Software Disable Trojans
    • Command Shell Trojan - Provides a backdoor to connect to through command-line access
      • Netcat
    • Covert Channel Tunneling Trojan (CCTT) - a RAT trojan; creates data transfer channels in previously authorized data streams

Infection Process:

  1. Creation of a Trojan using Trojan Construction Kit
  2. Create a Dropper
    • Used to install additional malware into the target system.
  3. Create a Wrapper
    • Wrappers - programs that allow you to bind an executable to an innocent file
  4. Propagate the Trojan
  5. Execute the Dropper

Trojan Port Numbers:

Trojan Name TCP Port
Death 2
Senna Spy 20
Blade Runner, Doly Trojan, Fore, Invisble FTP, WebEx, WinCrash 21
Shaft 22
Executor 80
Hackers Paradise 31,456
TCP Wrappers 421
Ini-Killer 555
Doom, Santaz Back 666
Silencer, WebEx 1001
DolyTrojan 1011
RAT 1095-98
SubSeven 1243
Shiva-Burka 1600
Trojan Cow 2001
Deep Throat 6670-71
Tini 7777
Dumaru.Y 10000
SubSeven 1.0-1.8, MyDoom.B 10080
VooDoo Doll, NetBus 1.x, GabanBus, Pie Bill Gates, X-Bill 12345
Whack a Mole 12361-3
NetBus 17300
Back Orifice 31337,8
SubSeven, PhatBot, AgoBot, Gaobot 65506

⚠️ - Its not necessary to know every possible trojan port in the history for the CEH exam, it's good for understanding.

Trojan Countermeasures

  1. Avoid cicking on unusual or suspect email attachments
  2. Block unused ports
  3. Monitor network traffic
  4. Avoid downloading from unstrusted sources
  5. Install & updated anti-virus software
  6. Scan removable media before use
  7. Validate file integrity of all externally sourced software
  8. Enable auditing
  9. Configure Host-Based firewalls
  10. Use IDS

Techniques

  • netstat -an - shows open ports in numerical order
  • netstat -b - displays all active connections and the processes using them
  • Process Explorer - Microsoft tool that shows you everything about running processes
  • Registry Monitoring Tools
    • SysAnalyzer
    • Tiny Watcher
    • Active Registry Monitor
    • Regshot
  • Msconfig - Windows program that shows all programs set to start on startup
  • Tripwire - integrity verifier that can act as a HIDS in protection against trojans
  • SIGVERIF - build into Windows to verify the integrity of the system
    • Log file can be found at c:\windows\system32\sigverif.txt
    • Look for drivers that are not signed

Malware Analysis

Malware analysis is the study or process of determining the functionality, origin and potential impact of a given malware sample such as a virus, worm, trojan horse, rootkit, or backdoor.

Types of Malware analysis:

  1. Static (Code Analysis) - performed by fragmenting the binary file into individual elements that can be analyzed without executing them.

    • File fingerprinting
    • Local & online scanning of elements to see if they match known malware profiles
    • String searching
    • Identifying packers/obfuscators used
    • Identifying the PE's (portable executable) information
    • Identify dependencies
    • Malware disassembly

  2. Dynamic (Behavioral Analysis) - performed by executing the malware to see what effect it has on the system.

    • System baselining
    • Host integrity monitoring

  • Tools for Disassembling | Debugging | Reverse Engineering:

    • IDA Pro
    • OllyDdg
    • Ghidra by NSA

  • Sheepdip - Dedicated computer which is used to test files on removable media for viruses before they are allowed to be used with other computers.

Steps

  1. Make sure you have a good test bed
    • Use a VM with NIC in host-only mode and no open shares
  2. Analyze the malware on the isolated VM in a static state
    • Tools - binText and UPX help with looking at binary
  3. Run the malware and check out processes
    • Use Process Monitor, etc. to look at processes
    • Use NetResident, TCPview or even Wireshark to look at network activity
  4. Check and see what files were added, changed, or deleted
    • Tools - IDA Pro, VirusTotal, Anubis, Threat Analyzer
  • Preventing Malware
    • Make sure you know what is going on in your system
    • Have a good antivirus that is up to date
      • Airgapped - isolated on network

Rootkits

  • Software put in place by attacker to obscure system compromise
  • Hides processes and files
  • Also allows for future access
  • Examples
    • Horsepill - Linus kernel rootkit inside initrd
    • Grayfish - Windows rootkit that injects in boot record
    • Firefef - multi-component family of malware
    • Azazel
    • Avatar
    • Necurs
    • ZeroAccess
  • Hypervisor level - rootkits that modify the boot sequence of a host system to load a VM as the host OS
  • Hardware - hide malware in devices or firmware
  • Boot loader level - replace boot loader with one controlled by hacker
  • Application level - directed to replace valid application files with Trojans
  • Kernel level - attack boot sectors and kernel level replacing kernel code with back-door code; most dangerous
  • Library level - use system-level calls to hide themselves
  • One way to detect rootkits is to map all the files on a system and then boot a system from a clean CD version and compare the two file systems