qsfuzz (Query String Fuzz) is a tool that allows you to write simple rules in YAML that define what value you want to inject, and what is the outcome you expect if that injection is successful. Pass in a list of URLs, with query strings, and qsfuzz will replace the query string values with your injections to determine if it's vulnerable.
qsfuzz injections are done one-at-a-time for URLs with multiple query strings to ensure requests aren't broken if certain parameters are relied on. URLs that don't have query strings will be ignored.
go get github.com/ameenmaali/qsfuzz
qsfuzz takes URLs (with query strings) from stdin, of which you will most likely want in a file such as:
$ cat file.txt https://google.com/home/?q=2&d=asd https://my.site/profile?param1=1¶m2=2 https://my.site/profile?param3=3
qsfuzz also requires a config file (see
config-example.yaml for an example) which contains the relevant rules to
evaluate against. This should be a YAML file and formatted such as:
$ cat config.yaml rules: ruleName: description: This is my rule description injections: - injectionValue1 - injectionValue2 expectation: responseContents: - injectionValue1 responseCodes: - 200 rule2Name: description: This is my 2nd rule description injections: - '"><h2>asd</h2>' expectation: responseContents: - <h2>asd</h2> responseHeaders: Content-Type: html slack: channel: "#channel-name" botToken: "MY-BOT-TOKEN"
Important Notes for Config files
You can have as many rules as you'd like (of course this will slow down evaluations). These are the currently supported fields, annotated with comments above the field:
# This should never change, and indicates the start of the rules list rules: # This should be set to the rule's name you are defining ruleName: # This should be a short description of what the rule's purpose is description: # This is a list (1 or more) of additional query strings to add to requests (that aren't already included in the URLs provided) # This will also keep all URLs that don't normally have query strings, and inject these params as the only ones. extraParams: - # This is a list (1 or more) of injection values to inject within query strings injections: - - # There are several fields within expectation that will be defined below. At least 1 of the below categories must be present to be evaluated expectation: # This is a list (1 or more) of which include a value within a response body that should be present to indicate it is vulnerable. responseContents: - # This is a list (1 or more) of which include a response code that should be present to indicate it is vulnerable. responseCodes: - # This is a list (1 or more) of which include a response header that should be present to indicate it is vulnerable. responseHeaders: - # This is a list (1 or more) of which include a response length that should be within a 10% variance to indicate it is vulnerable. responseLengths: - # Including this heuristics key (optional) will do a couple things. It will send a request to a baseline URL with no parameter injections, # then match the baselineMatches expectations against the heuristic injection. # (i.e. does injecting ' give a 500, but injecting '' in a query string match the baseline request with a 200 code) heuristics: # This is an injection that if successful matches the original baseline request baselineMatches injection: "''" # This is a list (1 or more) which check if the defined category matches the baseline request # (i.e. heuristic test match matches the baseline request) baselineMatches: - "responseCode" # Optional key, to be used if -to-slack command line flag is enabled. Sends positive results to Slack slack: # The Slack channel you wish to send results to channel: "#channel-name" # The bot token for your Slack app to use for authentication botToken: "MY-BOT-TOKEN"
expectation section, 3 types of matching are supported:
responseContentssearches the response body for the contents within it
responseCodesmatches against the response code of the request (redirects are followed automatically, however)
responseHeadersdoes a "contains" match against the response header. If
responseHeadersis set to
html, then a header value of
text/htmlwill successfully match
- If you have more than 1
expectation, each of the evaluation categories must be matched for the evaluation to be successful, however only 1 of each category (i.e.
responseCodes) needs to match
Take the following example:
rules: XssDetection: description: This rule checks for reflected parameters injections: - '"><h2>asd</h2>' - <asd>test</asd> expectation: responseContents: - <h2>asd</h2> - <asd>test</asd> responseHeaders: Content-Type: html
The above rule will inject
<asd>test</asd> in query string values, and check for
<asd>test</asd> in the response contents.
In order to be successful, one of the 2
responseContents must be matched, as well as the
Content-Type response header including
html within it.
There is rudimentary templating functionality within the rule's injection points, which can be done by inserting the supported variable in square brackets
This is to allow for some dynamic payloads where you need them. Here are the following fields supported within the templating (these are all related to the URL that is
being assessed at that point in time):
fullurl(This is the full URL, including query strings, of the URL being targeted in a given request)
domain(This is the domain of the URL being targeted in a given request)
path(This is the path, not including query strings, of the URL being targeted in a given request)
originalvalue(This is the query strings original value before being altered with the injection. i.e.
asdis the original value)
An example on using these are:
rules: CallbackFuzz: description: Test for open redirects and potential SSRFs by checking for certain responses or callbacks to your server extraParams: - url - redirect_url injections: - "http://[[domain]].example.net/" - "//example.net?targetUrl=[[fullurl]]" - "https://example.net?target=[[domain]][[path]]" - "@example.net" expectation: responseContents: - Example Domain
Heuristics Based Testing
heuristics key in your config file is optional. It will do a couple things:
- It will send a request to a baseline URL with no parameter injections, and store that response
- It will then match whatever categories are defined in the
baselineMatchesagainst the baseline request
- Then, if both the rule injection are matched and the heuristics test, the rule will be a positive match.
Take the following example:
SqlInjectionCheck: description: Test for potential SQL injections by injecting characters to break SQL statements injections: - "[[originalvalue]]'" expectation: responseCodes: - 500 heuristics: injection: "[[originalvalue]]''" baselineMatches: - "responseCode"
This rule will first check for injecting
' in query strings, appended to the query string's original value. If a response back is
500, it will then do a heuristics based test.
A baseline request will be sent to understand what the endpoint normally returns without any injected query strings. Then, based
on the defined categories in
baselineMatches (which in this case is
responseCode), a check will be done to see if the response
code for the heuristic request matches the baseline request. So does
' give a
500 response, but
'' gives a
Including this key will result in more requests being sent, but there is some basic caching logic to ensure the same URLs aren't hit more than necessary.
Currently, the supported
responseCode(Matches the response code against the baseline request's response code)
responseLength(Matches the response code against the baseline request's response length, within a 10% variance)
responseHeader(Matches the response code against the baseline request's response headers. This is probably not very useful or worth using)
responseContent(Matches the response code against the baseline request's response code. This is probably not very useful or worth using)
qsfuzz also supports sending positive matches to Slack. This can be done by adding in the following Slack Config in your config.yaml file.
This should be done as a separate key from
rules (see above example), which is the
slack: channel: "#channel-name" botToken: "MY-BOT-TOKEN"
This is particularly valuable in blind attacks, such as blind SSRF, where
qsfuzz won't necessarily know whether it's successful, but your callback server receives a hit.
You can add some data, such as the above supported parameters, within the injection to also send the vulnerable, injected URL within the request.
$ qsfuzz -h Usage of qsfuzz: -H string Headers to add in all requests. Multiple should be separated by semi-colon -c string File path to config file, which contains fuzz rules -config string File path to config file, which contains fuzz rules -cookies string Cookies to add in all requests -d Send requests with decoded query strings/parameters (this could cause many errors/bad requests) -debug Debug/verbose mode to print more info for failed/malformed URLs or requests -decode Send requests with decoded query strings/parameters (this could cause many errors/bad requests) -headers string Headers to add in all requests. Multiple should be separated by semi-colon -no-redirects Do not follow redirects for HTTP requests (default is true, redirects are followed) -nr Do not follow redirects for HTTP requests (default is true, redirects are followed) -s Only print successful evaluations (i.e. mute status updates). Note these updates print to stderr, and won't be saved if saving stdout to files -silent Only print successful evaluations (i.e. mute status updates). Note these updates print to stderr, and won't be saved if saving stdout to files -t int Set the timeout length (in seconds) for each HTTP request (default 15) -timeout int Set the timeout length (in seconds) for each HTTP request (default 15) -to-slack Send positive matches to Slack (must have Slack key properly setup in config file) -ts Send positive matches to Slack (must have Slack key properly setup in config file) -version Get the current version of qsfuzz -w int Set the concurrency/worker count (default 25) -workers int Set the concurrency/worker count (default 25)
qsfuzz is best used when combining with other tools, such as hakcrawler or waybackurls
Get URLs from Wayback Machine with
waybackurls and fuzz the parameters with
cat hosts.txt | waybackurls | qsfuzz -c config.yaml
cat urls.txt | qsfuzz -c config.yaml -cookies "cookie1=value; cookie2=value2" -H "Authorization: Basic qosakdq==
Crawl with hakrawler, assess with qsfuzz, and send results to Slack:
cat hosts.txt | hakrawler | qsfuzz -c config.yaml -to-slack