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Thread: Steganography and the Attacks

  1. #1

    Steganography and the Attacks

    Steganography and the Attacks

    Attacks on Steganography:
    Two aspects of attacks on steganography are detection and destruction of embedded message. Any object can be manipulated with the intent of destroying some hidden information whether an embedded message exist or not. .
    Attacking steganographic algorithm is very similar to attacking cryptographic algorithms and similar techniques apply. If the original unmodified file used as a cover by the stegosystem is available to an attacker or investigator all he has to do is a bit-by-bit comparison with the suspect version in order to establish steganographic content. That is why publicly available files- sound files from CD or images from internet should never be used as a cover. The strength of a steganographic algorithm depends on its ability to successfully withstand attacks.
    A few of the possible attacks are as follows:
    File Only: The attacker has access to the file and must determine if there is a message hidden inside. This is the weakest form of attack, but it is also the minimum threshold for a successful steganography. File only attack relies on statistical analysis to reveal the presence of a message in a file.
    File an Original copy: In some cases the attacker may have a copy of the file with the encoded message and a copy of the original. If the two files are different, there must be some hidden information inside. The attacker can simply replace the message with the original to destroy the hidden information.
    Reformat Attack: One possible attack is to change the format of the file. This can work because different file formats store data in different ways.
    Compression Attack. One of the simplest forms of attack is to compress the file. Compression algorithms try to remove extraneous information from a file. A good example is the JPEG, where the image format is not accurate but rather an approximate of the original.
    Another possible attack is to simply destroy the message or encode a new message if you have access to the algorithm. A message with hidden information maybe detectable, but this only becomes an issue if someone is trying to detect it. Detecting hidden information will save time with message elimination by processing only the messages with hidden information.
    Visual Attack
    The visual attack is a stego-only-attack that strips away part of the object in way that allows for a human to search for visual anomalies. The most common attack is to display the least significant bit of an object; Digital equipments such as cameras and scanners are not perfect and often leave echoes in the least significant bits. These completely random noises indicate the existence of a hidden message. The average ear can pick up subtle difference in sound. However, this is a very slow and costly attack.
    Structural Attack
    Steganographic algorithms leave behind a characteristic structure to the data. The format of the data file is often different when information is embedded. The attacker may detect the presence of a message by examining the statistical profile of the bits. These changes to the data file usually fall into easily detectable pattern that gives an indication of a hidden message.
    Statistical Attack
    Statistical attack is similar to visual attack. The fact that most programs relies on the assumption that least significant bit of a cover file is random and therefore overwritten with a secret message is not necessarily true. The idea of the statistical attack is to compare the frequency distribution of a potential cover file with the theoretically expected distribution of the cover file. If the new data does not have the same statistical profile as the standard data is expected to have, then it probably contains a hidden message.





  2. #2

    Re: staganography.pdf

    Quote Originally Posted by rounak1991 View Post
    Steganography and the Attacks

    Attacks on Steganography:
    Two aspects of attacks on steganography are detection and destruction of embedded message. Any object can be manipulated with the intent of destroying some hidden information whether an embedded message exist or not. .
    Attacking steganographic algorithm is very similar to attacking cryptographic algorithms and similar techniques apply. If the original unmodified file used as a cover by the stegosystem is available to an attacker or investigator all he has to do is a bit-by-bit comparison with the suspect version in order to establish steganographic content. That is why publicly available files- sound files from CD or images from internet should never be used as a cover. The strength of a steganographic algorithm depends on its ability to successfully withstand attacks.
    A few of the possible attacks are as follows:
    File Only: The attacker has access to the file and must determine if there is a message hidden inside. This is the weakest form of attack, but it is also the minimum threshold for a successful steganography. File only attack relies on statistical analysis to reveal the presence of a message in a file.
    File an Original copy: In some cases the attacker may have a copy of the file with the encoded message and a copy of the original. If the two files are different, there must be some hidden information inside. The attacker can simply replace the message with the original to destroy the hidden information.
    Reformat Attack: One possible attack is to change the format of the file. This can work because different file formats store data in different ways.
    Compression Attack. One of the simplest forms of attack is to compress the file. Compression algorithms try to remove extraneous information from a file. A good example is the JPEG, where the image format is not accurate but rather an approximate of the original.
    Another possible attack is to simply destroy the message or encode a new message if you have access to the algorithm. A message with hidden information maybe detectable, but this only becomes an issue if someone is trying to detect it. Detecting hidden information will save time with message elimination by processing only the messages with hidden information.
    Visual Attack
    The visual attack is a stego-only-attack that strips away part of the object in way that allows for a human to search for visual anomalies. The most common attack is to display the least significant bit of an object; Digital equipments such as cameras and scanners are not perfect and often leave echoes in the least significant bits. These completely random noises indicate the existence of a hidden message. The average ear can pick up subtle difference in sound. However, this is a very slow and costly attack.
    Structural Attack
    Steganographic algorithms leave behind a characteristic structure to the data. The format of the data file is often different when information is embedded. The attacker may detect the presence of a message by examining the statistical profile of the bits. These changes to the data file usually fall into easily detectable pattern that gives an indication of a hidden message.
    Statistical Attack
    Statistical attack is similar to visual attack. The fact that most programs relies on the assumption that least significant bit of a cover file is random and therefore overwritten with a secret message is not necessarily true. The idea of the statistical attack is to compare the frequency distribution of a potential cover file with the theoretically expected distribution of the cover file. If the new data does not have the same statistical profile as the standard data is expected to have, then it probably contains a hidden message.
    [MENTION=12151]rounak[/MENTION]
    Please post the thread in the relevant sections only, if you need any help please contact admin ...........

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