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Xorsearch

May 26, 2018

Search for a given string in an XOR or ROL encoded binary file

XORSearch is a program to search for a given string in an XOR or ROL encoded binary file. An XOR encoded binary file is a file where some or all bytes have been XORed with a constant value the key. A ROL or ROR encoded file has it bytes rotated by a certain number of bits the key. XOR and ROL/ROR encoding is used by malware programmers to obfuscate strings like URLs.

XORSearch will try all XOR keys 0 to 255 and ROL keys 1 to 7 when searching. I programmed XORSearch to include key 0, because this allows to search in an unencoded binary file X XOR 0 equals X.

If the search string is found, XORSearch will print it until the 0 byte zero is encountered or until 50 characters have been printed, which ever comes first. 50 is the default value, it can be changed with option -l. Unprintable characters are replaced by a dot.

WWW http//blog.didierstevens.com/programs/xorsearch/