skipfish/dictionaries/README-FIRST

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This directory contains four alternative, hand-picked Skipfish dictionaries.
Before you pick one, you should understand several basic concepts related to
dictionary management in this scanner, as this topic is of critical importance
to the quality of your scans.
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Dictionary management basics:
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1) Each dictionary may consist of a number of extensions, and a number of
"regular" keywords. Extensions are considered just a special subset of
the keyword list.
2) You can specify the dictionary to use with a -W option. The file must
conform to the following format:
type hits total_age last_age keyword
...where 'type' is either 'e' or 'w' (extension or wordlist); 'hits'
is the total number of times this keyword resulted in a non-404 hit
in all previous scans; 'total_age' is the number of scan cycles this
word is in the dictionary; 'last_age' is the number of scan cycles
since the last 'hit'; and 'keyword' is the actual keyword.
Do not duplicate extensions as keywords - if you already have 'html' as
an 'e' entry, there is no need to also create a 'w' one.
There must be no empty or malformed lines, comments, etc, in the wordlist
file. Extension keywords must have no leading dot (e.g., 'exe', not '.exe'),
and all keywords should be NOT url-encoded (e.g., 'Program Files', not
'Program%20Files'). No keyword should exceed 64 characters.
If you omit -W in the command line, 'skipfish.wl' is assumed.
3) When loading a dictionary, you can use -R option to drop any entries
that had no hits for a specified number of scans.
4) Unless -L is specified in the command line, the scanner will also
automatically learn new keywords and extensions based on any links
discovered during the scan.
5) Unless -L is specified, the scanner will also analyze pages and extract
words that would serve as keyword guesses. A capped number of guesses
is maintained by the scanner, with older entries being removed from the
list as new ones are found (the size of this jar is adjustable with the
-G option).
These guesses would be tested along with regular keywords during brute-force
steps. If they result in a non-404 hit at some point, they are promoted to
the "proper" keyword list.
6) Unless -V is specified in the command line, all newly discovered keywords
are saved back to the input wordlist file, along with their hit statistics.
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Dictionaries are used for the following tasks:
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1) When a new directory, or a file-like query or POST parameter is discovered,
the scanner attempts passing all possible <keyword> values to discover new
files, directories, etc.
2) If you did NOT specify -Y in the command line, the scanner also tests all
possible <keyword>.<extension> pairs in these cases. Note that this may
result in several orders of magnitude more requests, but is the only way
to discover files such as 'backup.tar.gz', 'database.csv', etc.
3) For any non-404 file or directory discovered by any other means, the scanner
also attempts all <node_filename>.<extension> combinations, to discover,
for example, entries such as 'index.php.old'.
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Supplied dictionaries:
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1) Empty dictionary (-).
Simply create an empty file, then load it via -W. If you use this option
in conjunction with -L, this essentially inhibits all brute-force testing,
and results in an orderly, link-based crawl.
If -L is not used, the crawler will still attempt brute-force, but only
based on the keywords and extensions discovered when crawling the site.
This means it will likely learn keywords such as 'index' or extensions
such as 'html' - but may never attempt probing for 'log', 'old', 'bak', etc.
Both these variants are very useful for lightweight scans, but are not
particularly exhaustive.
2) Extension-only dictionary (extensions-only.wl).
This dictionary contains about 90 common file extensions, and no other
keywords. It must be used in conjunction with -Y (otherwise, it will not
behave as expected).
This is often a better alternative to a null dictionary: the scanner will
still limit brute-force primarily to file names learned on the site, but
will know about extensions such as 'log' or 'old', and will test for them
accordingly.
3) Basic extensions dictionary (minimal.wl).
This dictionary contains about 25 extensions, focusing on common entries
most likely to spell trouble (.bak, .old, .conf, .zip, etc); and about 1,700
hand-picked keywords.
This is useful for quick assessments where no obscure technologies are used.
The principal scan cost is about 42,000 requests per each fuzzed directory.
Using it without -L is recommended, as the list of extensions does not
include standard framework-specific cases (.asp, .jsp, .php, etc), and
these are best learned on the fly.
You can also use this dictionary with -Y option enabled, approximating the
behavior of most other security scanners; in this case, it will send only
about 1,700 requests per directory, and will look for 25 secondary extensions
only on otherwise discovered resources.
3) Standard extensions dictionary (default.wl).
This dictionary contains about 60 common extensions, plus the same set of
1,700 keywords. The extensions cover most of the common, interesting web
resources.
This is a good starting point for assessments where scan times are not
a critical factor; the cost is about 100,000 requests per each fuzzed
directory.
In -Y mode, it behaves nearly identical to minimal.wl, but will test a
greater set of extensions on otherwise discovered resources, at a relatively
minor expense.
4) Complete extensions dictionary (complete.wl).
Contains about 90 common extensions and 1,700 keywords. These extensions
cover a broader range of media types, including some less common programming
languages, image and video formats, etc.
Useful for comprehensive assessments, over 150,000 requests per each fuzzed
directory.
In -Y mode - see default.wl, offers the best coverage of all three wordlists
at a relatively low cost.
Of course, you can customize these dictionaries as seen fit. It might be, for
example, a good idea to downgrade file extensions not likely to occur given
the technologies used by your target host to regular 'w' records.
Whichever option you choose, be sure to make a *copy* of this dictionary, and
load that copy, not the original, via -W. The specified file will be overwritten
with site-specific information (unless -V used).
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Bah, these dictionaries are small!
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Keep in mind that web crawling is not password guessing; it is exceedingly
unlikely for web servers to have directories or files named 'henceforth',
'abating', or 'witlessly'. Because of this, using 200,000+ entry English
wordlists, or similar data sets, is largely pointless.
More importantly, doing so often leads to reduced coverage or unacceptable
scan times; with a 200k wordlist and 80 extensions, trying all combinations
for a single directory would take 30-40 hours against a slow server; and even
with a fast one, at least 5 hours is to be expected.
DirBuster uses a unique approach that seems promising at first sight - to
base their wordlists depending on how often a particular keyword appeared in
URLs seen on the Internet. This is interesting, but comes with two gotchas:
- Keywords related to popular websites and brands are heavily
overrepresented; DirBuster wordlists have 'bbc_news_24', 'beebie_bunny',
and 'koalabrothers' near the top of their list, but it is pretty unlikely
these keywords would be of any use in real-world assessments of a typical
site, unless it happens to be BBC.
- Some of the most interesting security-related keywords are not commonly
indexed, and may appear, say, on no more than few dozen or few thousand
crawled websites in Google index. But, that does not make 'AggreSpy' or
'.ssh/authorized_keys' any less interesting.
Bottom line is, poor wordlists are one of the reasons why some other web
security scanners perform worse than expected, so please - be careful. You will
almost always be better off narrowing down or selectively extending the
supplied set (and possibly contributing back your changes upstream!), than
importing a giant wordlist from elsewhere.