SEARCH FOR WRITTEN PASSWORDS
The nondisclosure of passwords for both encryption and authentication can be
a source of frustration for forensic analysts. 256-bit encrypted files using com-
plex passwords cannot be cracked in a meaningful timeframe. Understandably,
suspects are often not obliging in giving up these passwords. In the UK “The
77
Ram
Regulation of Investigatory Powers Act 2000” makes it a criminal offence to “fail
to disclose when requested a key to any encrypted information.” However, the
usual defense against this is for the suspect to claim to have forgotten their pass-
word. In these circumstances there is little that can be done by law enforcement.
Ironically, if the suspect later admits to knowing the password and reveals it, they
can be charged with the offence of originally withholding it. However, as most
malicious hackers understand the need for independent, unique and complex pass-
words to ensure privacy, then it is possible that the password is too difficult for
them to remember; hence it could be written down. All papers in the area should
be seized as these may contain passwords. Books should be seized too, as one
common practice is to insert written passwords within their pages. Other common
hiding places should also be considered, e.g., under the mattress of a bed. Finding
hard copies of passwords is sometimes the only method of deciphering encrypted
data from the media.
FORENSIC ACQUISITION
The most fundamental stage to ensuring the evidence remains omissible is to ensure
the original image does not get altered during the process. This section discusses
how to maintain the integrity of the evidence during the creation of an image from
the media.
RAM
There is an inherent risk involved in acquiring a memory dump, thus a risk assess-
ment should be performed to establish the potential benefit against the risk for the
given situation. If it is both required and relatively safe then it may be performed,
however, extreme care should be taken to both limit, and explain, the acquisition
footprint which will be left on system. While courts are beginning to accept that
a footprint will be introduced (
Wade, 2011
), it is essential that the correct tools
and methods are used and that the entire process is documented, preferably video
recorded, to reduce the likelihood that the acquisition footprint becomes the undo-
ing of a case. Some applications such as chat room, malware and cryptography
programs may employ anti-memory dumping technologies designed to prevent
data being read from protected areas of RAM. These protection mechanisms
data dump garbage, e.g., random values or zeroes instead of the valid contents of
memory. Other applications utilize anti-debugging protection that can cause a sys-
tem to lock or reboot on an attempt to read protected RAM. Due to the devel-
opment of these anti-forensic methods it is desirable to use a memory- capturing
tool that operates in “kernel” rather than “user” mode. Kernel mode allows unre-
stricted accesses to the underlying hardware, e.g., RAM, and is less likely to com-
promise the evidence through a system crash, nor will it provide false evidence
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