1 / 32

Malware

Malware. Ge Zhang Karlstad Univeristy. Focus. What malware are Types of malware How do they propagate How do they hide How to detect them. What is a malware ?. A Malware is a set of instructions that run on your computer and make your system do something that an attacker wants it to do.

taji
Télécharger la présentation

Malware

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Malware Ge Zhang Karlstad Univeristy

  2. Focus • What malware are • Types of malware • How do they propagate • How do they hide • How to detect them

  3. What is a malware ? • A Malware is a set of instructions that run on your computer and make your system do something that an attacker wants it to do.

  4. Malware zoo (1) • Virus: attaches it self to a program and propagates copies of itself to other programs • Worm: program that propagates copies of itself to other computers • Logic bomb: Triggers action when condition occurs • Trojan horse: Program that contains unexpected additional functions • Backdoor: Program modification that allows unauthorized access to functionality • Exploits: code specific to a single vulnerability or a set of vulnerabilities

  5. Malware zoo (2) • Downloaders: Program that installs other items on a machine that is under attack • Auto-rooter: Hacker tools used to break into new machines automatically • Kit (virus generator): tools to generate new viruses automatically • Spammer program: tools to produce large volume of unwanted emails. • Flooders: tools to generate large volume of unwanted traffics • Keyloggers: capture keystrokes on a compromised computer. • Zombie: Program activated on an infected machine that is actived to launch attacks on other machines

  6. Number of malware signatures Symantec report 2009

  7. Viruses • 4 phases: • Dormant phase: It is idle, waiting for some event • Propagation phase: Copy itself into other programs • Triggering phase: activated to perform some intended actions • Execution phase: execute the payload, maybe harmless

  8. DOS boot Sequence • ROM BIOS: locates the master boot sector • Master boot sector: partition table • DOS boot sector: executable codes and FAT

  9. DOS bootstrap virus • A bootstrap virus resides in one of the boot sectors • Becomes active before DOS is operational • Example: stoned virus

  10. How a bootstrap virus takes control?

  11. Parasitic virus • Overwriting virus • Appending virus

  12. Companion virus • Do not need to modify the original files • Create a new file with a specific name

  13. Lifecycle of virus • A virus gets created and released • The virus infects several machines • Samples are sent to anti-virus companies • Records a signature from the virus • The companies include the new signature in their database • Their scanner now can detect the virus

  14. Virus hidden mechanisms • Encrypt virus code with random generated keys • What happens if the boot area is encrypted?

  15. Virus hidden mechanisms (2) • Polymorphism: randomly changes the encryption/decryption portion of a virus • Change key each time the virus starts • Change the range of plaintext • Change the location of encryption subroutine • Countermeasure: scan in RAM (after self-decrypting)

  16. Virus hidden mechanisms (3) • Entry point changes • Random execution (JMP)

  17. Macro viruses • Macro: an executable program embedded in a document to automate repetitive tasks. (save keystrokes) • Application-dependent, e.g., MS office • Cross the O.S. and hardware platform • Why virus writers like macro viruses? • Easy to learn • Easy to write • Popularity of MS office

  18. How macro virus works • Every word document is based on a template • When an existing or new document is opened, the template setting are applied first • A global template: NORMAL.DOT

  19. Worm • Worm: self-replicating over networks, but not infecting program and files • Example: Morris worm, blaster worm

  20. The structure of worms • Target locator (find the target) • Email address collector • IP/port scanner • Warhead • Break into remote machines • Propagation • Automatically sending emails • Automatically attack remote hosts • Remote control and update • Download updates from a web server • Join a IRC channel • Lifecycle management • Commit suicide • Avoid repeatedly infecting the same host • Payload

  21. State of Worm Technology • Multiplatform: Windows, unix, mac, … • Multiexploit: web server, browser, email,… • Ultrafast spreading: host/port scanning • Polymorphic: Each copy has new code generated by equivalent instructions and encryption techniques. • Metamorphic: different behavior patterns (prepared) • Transport vehicles: for the payloads (spread attacking tools and zombies) • Zero-day exploit: self-updated

  22. discussion • Is it a good idea to spread worms with system patches?

  23. Trojan • A program with hidden side-effects that are not specified in the program documentation and are not intended by the user executing the program

  24. What a trojan can do • Remote administration trojans: attackers get the complete control of a PC • Backdoor: steal data and files • Distributed attacks: zombie network • Password stealers: capture stored passwords • Audio, video capturing: control devices • Keyloggers: capture inputting passwords • Adware: popup advertisements

  25. Familiar with your PC • Startup programs/services • Frequently used IP ports • 20/21 FTP • 23 Telnet • 25 SMTP • 80 WWW • Netstat

  26. Malware Payloads • No payload • Payload without damage • Only display some information • Payload with little impact • Modify documents (wazzu virus) • Payload with heavy impact • Remove files, format storage • Encrypting data (blackmail) • Destroy hardware (W95.CIH): rewrite flash bios • DDoS attacks • Steal data for profit

  27. Malware naming • CARO (computer antivirus researchers organization) • CARO naming convention (1991) • <family_name>.<group_name>.<Infective_length>.<variant>.<modifier> • e.g., cascade.1701.A. • Platform prefix • win32.nimda.A@mm

  28. Malware defenses (1) • Detection: once the infection has occurred, determine that it has occurred and locate the virus • Identification: once detection has been achieved, identify the specific virus that has infected a program • Removal: once the specific virus has been identified, remove the virus from the infected program and restore it to its original state

  29. Malware defenses (2) • The first generation scanner • Virus signature (bit pattern) • Maintains a record of the length of programs • The second generation scanner • Looks for fragments of code (neglect unnecessary code) • Checksum of files (integrity checking) • Virus-specific detection algorithm • Deciphering (W95.Mad, xor encrypting) • Filtering

  30. Malware defenses (3) • The third generation scanner • Identify a virus by its actions • The fourth generation scanner • Include a variety of anti-virus techniques • Collection method • Using honeypots

  31. In the future… • New spreading methods: e.g., RFID Infected! Infected! Infected!

  32. Key points • Taxonomy of malwares • The difference between virus and worm • How does bootstrap/companion/parasitic/macro virus propagate • Virus hidden method • The structure of worm • What a trojan/malware payload can do • Malware naming standard (CARO) • Malware defenses methods

More Related