1. Week-14 (Lecture-1) Malicious software and antivirus: 1. Malware A user can be tricked or forced into downloading malware comes in many forms, Ex. viruses, Trojan horses, spyware and worms. 2. Viruses A programs that can replicate their structures They can infect others files. Stealing the data is common task. 3. Trojan horse It is a general term for malicious software. software that pretends to be harmless. So that a user willingly allows it to be downloaded.

2. Week-14 (Lecture-1) 4. Spyware A programs that surreptitiously monitor activity on a computer It report that information to others without the user's consent. 5. Worms Worm replicates themselves throughout a computer network, performing malicious tasks throughout. 6. Botnet A botnet is a network of "zombie" computers "bot" that performs large-scale malicious act.

3. Week-14 (Lecture-1) Antivirus: Antivirus programs and Internet security programs protect from viruses. They detect and usually eliminate viruses. A user would pay for antivirus software. User can download it from a host of free security. Ex. Norton, AVIRA, AVST, Microsoft security essentials etc. Buffer overflow attacks: An attack that could get full system access Cracking a computer using brute force. Mostly applications are incapable of adequate defense Ex- Through remote control process.

4. Week-14 (Lecture-2) Features of buffer overflow attacks: 1- Use of the Stack Use push and pop methods for memory space The stack is used heavily to store local variables and the return address of a function.

5. Week-14 (Lecture-2) 2- Real Stack Overflow Attacks: A real attack would try to place the address of the top of the stack in lieu of the return address, It followed by some horrible lines of assembly code Ex. call to another tool. Whole process takes only the transmission of a little script program. 3- Heap Overflow Attacks Programs use dynamically allocated memory as well as the stack A vulnerable program uses a call to something like strcpy It overwrite data on the heap The program will not always crash but not show Observing this behavior attacker finds way to corrupt the stack. Once the stack is corrupted, the attacker can get through.

6. Week-14 (Lecture-2) Data Encryption: The process of converting the data into cipher text It uses an algorithm (mathematical formula) Decryption is the reverse process of it. A secret key is used to encrypt and decrypt the data. Symmetric key and Asymmetric key are current techniques used in data encryption.