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9 Explain how an integer overflow works, in contrast to the stack b

9 Explain how an integer overflow works, in contrast to the stack b

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9. Explain how an integer overflow works, in contrast to the

stack-based buffer overflow.

Solution

Integer Overflow:

An integer overflow condition exists when an integer,

which has not been properly sanity checked, is used in the

determination of an offset or size for memory allocation,

copying, concatenation, or similarly. If the integer in

question is incremented past the maximum possible value,

it may wrap to become a very small, or negative number,

therefore providing a very incorrect value.

Consequences:

Exposure period:

Platform:

Languages: C, C++, Fortran, Assembly

Operating platforms: All

Integer overflows are for the most part only problematic

in that they lead to issues of availability. Common

instances of this can be found when primitives subject to

overflow are used as a loop index variable.

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In some situations, however, it is possible that an integer

overflow may lead to an exploitable buffer overflow

condition. In these circumstances, it may be possible for

the attacker to control the size of the buffer as well as the

execution of the program.

Recently, a number of integer overflow-based, buffer-

overflow conditions have surfaced in prominent software

packages. Due to this fact, the relatively difficult to exploit

condition is now more well known and therefore more likely

to be attacked. The best strategy for mitigation includes: a

multi-level strategy including the strict definition of proper

behavior frequent sanity checks; preferably at the object

level; and standard buffer overflow mitigation techniques.

Not accounting for integer overflow can result in logic

errors or buffer overflow.

Integer overflow errors occur when a program fails to

account for the fact that an arithmetic operation can result

in a quantity either greater than a data type\'s maximum

value or less than its minimum value. These errors often

cause problems in memory allocation functions, where

user input intersects with an implicit conversion between

signed and unsigned values. If an attacker can cause the

program to under-allocate memory or interpret a signed

value as an unsigned value in a memory operation, the

program may be vulnerable to a buffer overflow.

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9. Explain how an integer overflow works, in contrast to the stack-based buffer overflow. Solution Integer Overflow: An integer overflow condition exists when an integer, which has not been properly sanity checked, is used in the determination of an offset or size for memory allocation, copying, concatenation, or similarly. If the integer in question is incremented past the maximum possible value, it may wrap to become a very small, or negative number, therefore providing a very incorrect value. Consequences: Exposure period: Platform: Languages: C, C++, Fortran, Assembly Operating platforms: All Integer overflows are for the most part only problematic in that they lead to issues of availability. Common instances of this can be found when primitives subject to overflow are used as a loop index variable. In some situations, however, it is possible that an integer overflow may lead to an exploitable buffer overflow condition. In these circumstances, it may be possible f or the attacker to control the size of the buffer as well as the execution of the program. Recently, a number of integer overflow -based, bufferoverflow conditions have surfaced in prominent software packages. Due to this fact, the relatively difficult to exploit condition is now more well known and therefore more likely to be attacked. The best strategy for mitigation includes: a multi-level strategy including the strict definition of proper behavior frequent sanity checks; preferably at the object level; a ...
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