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The offset the string can be found at, in hexadecimal format, is the first field of each line. With the -n and -t flags, your output might look something like the following: $ strings -n16 -tx file.bin

Very useful if youвЂ™re cross-referencing with a hex editor, or simply want to know where in the file your string is. tx will return it in hex format, T-to in octal and -td in decimal. The -t flag will return the offset of the string within the file.

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16-bit wide encoding can often be found in firmware for embedded Windows (or devices which run Mono somewhere). If the dump is encoded as big-endian, use -eb. el specifies little-endian characters 16-bits wide (e.g. The strings -e flag specifies the encoding of the characters. This example command prints any ASCII strings longer than 16 to stdout. The -n flag specifies the minimum length of the string to be returned. The default minimum length of a string is 4. But it can be a little more granular than that. A basic strings file.bin will return all ASCII/ISO 8859-encoded strings 4 or longer. ItвЂ™s also more fully-featured than most people realise. It will return a list of null-terminated strings of printable characters. Strings is extremely useful for getting an initial lay-of-the-land. Regardless, the following tools are good all-rounders. If itвЂ™s for a more complex system, with an operating system like Linux, youвЂ™ll probably want to get files out of it. If you know that itвЂ™s for bare-metal, but you donвЂ™t have a datasheet, you might want to do some byte-level detective work. If you know the firmwareвЂ™s for a specific bare-metal MCU, youвЂ™ll likely just want to grab the datasheet and pull it straight into IDA. Once you got your firmware in a binary format, you can analyse it for interesting information.ДЄgain, itвЂ™s useful to remember context here. So, you got a binary? That donвЂ™t impress-a me much. ThereвЂ™s also the Micron introduction to NAND flash (which is where the above image is from). The author wrote an extremely useful tool called Nand-dump-tool.py, which should be used in conjunction with reading that post. I always, always end up going back to this amazing blog post on raw NAND dumps, every time I have to work with them. You can then start interrogating the dump with some of the strategies mentioned below. This means that youвЂ™re going to have to strip all these out of a raw dump before you have a contiguous file of the actual data you want. But, if you dump the whole chip raw, youвЂ™re going to have these вЂњspareвЂќ segments in the dump. TheyвЂ™re there for the controller to keep track of bad blocks, erase counters, etc. Out-of-band (OOB) вЂњspareвЂќ segments are inserted at the end of every page of data, or the end of each block, as you can see above. Well, itвЂ™s not that itвЂ™s that weird, itвЂ™s actually clever and useful when the data is still on a NAND chip, but you still need to do some pre-processing before youвЂ™ve got anything usable off-chip. Raw NAND dumpsДata is stored in a weird way on a NAND chip.

It looks roughly like this:ДЄll Motorola S-record, Intel HEX and TI-TXT files can be converted to binary using the bincopy python library. Memory addresses are prepended with an and data is represented in hex.

TI-TXT is a Texas Instruments format, usually for the MSP430 series.

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A full breakdown of the format can be found here.ДЄ similar vibe to SREC, Intel HEX lines all start with a colon. All S-record file lines start with a capital S. ThereвЂ™s a few common file formats you might come across: Motorola S-Record Before you can do much with these files, youвЂ™ll first need to get them into a binary format. If the device youвЂ™re targeting runs a bare-metal MCU, you might find that the firmware files are distributed in text files, with the bytes literally transcribed as hexadecimal (often with some prepended identifier codes and/or address offset/location, and possibly an appended checksum on each line). Use head, cat, hexdump, or your favourite GUI text editor. So, what in the file? Is it literally ASCII strings? Or a blob of binary data? Have a look. Similarly, trying to load the ROM filesystem for and embedded Linux-based SoC directly into IDA is a mugвЂ™s game. Running binwalk on SREC-encoded firmware for an RH850 is unlikely to help anyone. Do you know what chip itвЂ™s supposed to be running on? WhatвЂ™s the architecture? Little or big endian? Do you know if itвЂ™s running an RTOS? Is it running Linux? Just bare-metal?Д¬ontext will help guide you towards the right tool for the job. ItвЂ™s ALWAYS useful to remember the context of the file youвЂ™re working with. LetвЂ™s go through some strategies for getting useful data out of a firmware dump. Sometimes youвЂ™ll be faced with proprietary (barely documented) file formats, strange raw data quirks, or even encryption. Taking a firmware dump and turning it into something useful can sometimes be painful.

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Perhaps a raw read off a chip? An update file you downloaded off the internet? Now what?

Wxhexeditor tutorial