Introduction
This paper assumes a working knowledge of basic shellcoding techniques, and x86 assembly, I will not rehash these in this paper. I hope to teach you some of the lesser known shellcoding techniques that I have picked up, which will allow you to write smaller and better shellcodes. I do not claim to have invented any of these techniques, except for the one that uses the div instruction.
The multiplicity of mul
This technique was originally developed by Sorbo of darkircop.net. The mul instruction may, on the surface, seem mundane, and it's purpose obvious. However, when faced with the difficult challenge of shrinking your shellcode, it proves to be quite useful. First some background information on the mul instruction itself.
mul performs an unsigned multiply of two integers. It takes only one operand, the other is implicitly specified by the %eax register. So, a common mul instruction might look something like this:
movl $0x0a,%eax
mul $0x0a
This would multiply the value stored in %eax by the operand of mul, which in this case would be 10*10. The result is then implicitly stored in EDX:EAX. The result is stored over a span of two registers because it has the potential to be considerably larger than the previous value, possibly exceeding the capacity of a single register(this is also how floating points are stored in some cases, as an interesting sidenote).
So, now comes the ever-important question. How can we use these attributes to our advantage when writing shellcode? Well, let's think for a second, the instruction takes only one operand, therefore, since it is a very common instruction, it will generate only two bytes in our final shellcode. It multiplies whatever is passed to it by the value stored in %eax, and stores the value in both %edx and %eax, completely overwriting the contents of both registers, regardless of whether it is necessary to do so, in order to store the result of the multiplication. Let's put on our mathematician hats for a second, and consider this, what is the only possible result of a multiplication by 0? The answer, as you may have guessed, is 0. I think it's about time for some example code, so here it is:
xorl %ecx,%ecx
mul %ecx
What is this shellcode doing? Well, it 0's out the %ecx register using the xor instruction, so we now know that %ecx is 0.
Another film technique used in Mulan is a medium shot of when Mulan’s Father sees her for the first time, this scene is then put into a low shot as mulan gives the sword and emperor's crest to her father, a high shot is then shown in perspective of mulan watching her father look at the gifts. Then a medium shot is shown looking at mulan and her father hugging, this scene is truly heartwarming as mulan and her father meet for the first time. This was Mulan's return to her journey through the chinese war, this seals her hero's journey as she saved china and turned into a true hero.
Floating-point values are stored in an 8-bit representation: sign bit, followed by a 3-bit biased exponent and a 4-bit normalized significand with implied bit.
The book starts with Messala and Judah meeting when Messala returned. This is an example of a big difference that makes the story's plot more understandable in the movie. In the movie Mullach does not have a tongue. He is also said to be Simonides' legs. In the book Simonides only tells Mullach go follow Ben-Hur and befriend him. Mullach has a tongue and is not just
When Mulan goes off to protect her father, a small dragon, Mushu, goes after Mulan in order to help make sure she stays safe. “I am the guardian of lost souls. I am the powerful, the pleasurable, the indestructible, Mushu!“(Mulan). Mushu wants to protect Mulan and in turn protects her family name. Mushu made Mulan's journey much easier by helping her with every task a man was expected to be good at. Mushu encouraged Mulan not to quit and to get better than everyone else at the simple tasks. His guidance allowed Mulan to get better at being with men without as many
In the movie Mulan, based on the “Ballad of Mulan,” Disney inaccurately portrays her life causing many incongruities. In the movie, Mulan is portrayed as being weak and unskilled with weapons and horsemanship. The “real” Mulan, however, was said to have practiced with many weapons and warfare methods. As an article in The Epoch Times stated,” Mulan’s father…raised Mulan like a boy. She....practiced martial arts, archery, and fencing with her father….liked to read her father’s manuals on military strategy.” This would show that contrary to the Disney version, which depicts a young Mulan as being hopeless and weak, she was actually a fierce warrior who could carry herself into battle. In addition, the real Mulan also rode horses and shot arrows, differing from the incompetent Mulan that is depicted in the “We Are Men” scene of the movie. While Disney portrays Mulan as being unskilled and inadequate upon her entrance to camp, the actual Mulan was extremely adept to the art of war and extremely capable of holding her ground.
“Get ready Mulan, your serpentine salvation is at hand! For I have been sent by your ancestors to guide you through your masquerade!” Mulan's serpentine salvation is Mushu, the real hero in Disney's film Mulan, and can be seen through his actions in the story that relate to the characteristics of the hero cycle. Mushu receives the call, goes through apotheosis and finally travels down the road of trials, proving himself a hero to the Fa families ancestors. But how exactly does he do it?
The beginning of the cartoon Mulan opens to the ritual involved with transforming Mulan from an ordinary girl into an ideal potential wife. Society and family insist this is necessary and will be accomplished by bathing, donning a beautiful gown, applying white paint on her face and bright red lips. Through the entire process she is
Ok, this explains subnet addressing which is useful if you run a scanner, a firewall, a router or anything else that is bound to IP subnet addressing. Note that this only describes IPv4 subnets. Reading binary values
Hall, T., Strangman, N., & Mayer, A. (2009, February 11). Differentiated Instruction and Implications for UDL Implementation. Retrieved March 20, 2010, from CAST: http://www.cast.org/publications/ncac/ncac_diffinstructudl.html
At the outset, before the advent of user friendly operating systems, computers were run using the operating system CP/M (Control Program for Microcomputers). The program itself looked simple, but the complexity of its use meant that not many fully understood how to use it. As the program was also limited in use, since it was designed for 8-bit systems, a new operating system was needed when 16-bit IBM systems came out.
We are free to judge whether or not we would take the bundle that so often becomes Moll's pursuit in the future. It is at that instant that we can decide whether Moll was free to do so or controlled by something unavoidable, such as fate. If Moll was acting on freewill it is arguable that she would not repeat the same crime in the future, in fact she would most likely avoid any such acts that resulted in the terrible feelings she experienced during and after the first offense. For she says herself, "It is impossible to express the horror of my soul all the while I did it".
By having allocated an address to each partition, it allows the computer to know/identify every location within the memory sub-system. Memory purpose is to (As mentioned in the Von Neumann section of this documentation) to store instruction and hold data, with that data the memory unit will pass on the information to the CC and the ALU, to carry out the calculation and be able to have the data to execute them.
Malicious code, also known as malware, installed on a computer provides an attacker with the control over this machine. Therefore, malware can be defined as “a set of instructions that run on your computer and make your system do something that an attacker wants to do”. It is more common to see malicious code to be implemented in binary executable files. However, it can be implemented in almost any computer language. Attackers have used a huge number of scripting languages, word processing macro languages and a h...
One (or more) character is contained in an envelope of a start and stop bit.
A CPU has various discrete units to help it in these tasks for example there is an arithmetic and logic unit(ALU) that takes care of all the math and logical data comparisons that need to performed. A control register makes sure everything happens in the right sequence. The motherboard is the main circuit board inside the PC. All other components are either slotted into or soldered to this board.