By Pierre-Alain, Vincent Glaume

Show description

Read Online or Download A Buffer Overflow Study - Attacks and Defenses PDF

Best nonfiction_2 books

Plutarch's Lives, Volume VIII: Sertorius and Eumenes. Phocion and Cato the Younger (Loeb Classical Library No. 100)

Plutarch (Plutarchus), ca. 45–120 CE, was once born at Chaeronea in Boeotia in relevant Greece, studied philosophy at Athens, and, after coming to Rome as a instructor in philosophy, used to be given consular rank by way of the emperor Trajan and a procuratorship in Greece through Hadrian. He used to be married and the daddy of 1 daughter and 4 sons.

Extra info for A Buffer Overflow Study - Attacks and Defenses

Sample text

At this stage there is something important to notice: if the vulnerable program has been compiled with the option: --fomit-frame-pointer or with optimisation options then libsafe is useless and will not work properly. strnlen returns the maximum value between the length of the string src and max size (see explanations above). If there was an attempt to overflow the buffer, then strnlen() would return max size and the process would be stopped ( libsafe die). If this verification is passed then memcpy() is called and will copy the string referenced by src to the address referenced by dest.

To know if this second chunk is used or not it looks at the next chunk (the third chunk) and controls the less significant bit. At this point, we dont know the state of the second chunk. Therefore we will create a fake chunk with the required informations. 34 Firstly we fill falsify the field size of the second chunk by assigning -4. g the third one) is 4 bytes before the beginning of the second chunk. Then we set prev size of second chunk (which is also the size field of the third chunk) with SOMETHING & ~PREV_INUSE.

1 A new danger: plymorphic shellcodes Where the danger lies... As we have seen, a well-known kind of shellcode consists of a large amount of NOP bytes followed by the real code, and this means that this well-defined pattern can be discovered without great difficulties, at least in theory. In practice, some NIDS such as Prelude do it. To make this detection task more difficult, a new generation of shellcode has been created: polymorphic shellcodes. A first step has been to replace the NOP sequence by a more sophisticated set of instructions which finally has no effect, for instance empiling and depling several times the same register without changing its content.

Download PDF sample

A Buffer Overflow Study - Attacks and Defenses by Pierre-Alain, Vincent Glaume
Rated 4.26 of 5 – based on 22 votes