HTTP Fuzzing
HTTP Fuzzing¶
Nuclei supports fuzzing of HTTP requests based on rules defined in the fuzzing
section of the HTTP request. This allows creating templates for generic Web Application vulnerabilities like SQLi, SSRF, CMDi, etc without any information of the target like a classic web fuzzer.
Part¶
Part specifies what part of the request should be fuzzed based on the specified rules. Available options for this parameter are -
- query (
default
) - fuzz query parameters for URL
fuzzing:
- part: query # fuzz parameters in URL query
Support will be added for path
,header
,body
,cookie
, etc parts soon.
Type¶
Type specifies the type of replacement to perform for the fuzzing rule value. Available options for this parameter are -
- replace (
default
) - replace the value with payload - prefix - prefix the value with payload
- postfix - postfix the value with payload
- infix - infix the value with payload (place in between)
fuzzing:
- part: query
type: postfix # Fuzz query and postfix payload to params
Mode¶
Mode specifies the mode in which to perform the replacements. Available modes are -
- multiple (
default
) - replace all values at once - single - replace one value at a time
fuzzing:
- part: query
type: postfix
mode: multiple # Fuzz query postfixing payloads to all parameters at once
Note: default values are set/used when other options are not defined.
Filters¶
Multiple filters are supported to restrict the scope of fuzzing to only interesting parameter keys and values. Nuclei HTTP Fuzzing engine converts request parts into Keys and Values which then can be filtered by their related options.
The following filter fields are supported -
- keys - list of parameter names to fuzz (exact match)
- keys-regex - list of parameter regex to fuzz
- values - list of value regex to fuzz
These filters can be used in combination to run highly targeted fuzzing based on the parameter input. A few examples of such filtering are provided below.
# fuzzing command injection based on parameter name value
fuzzing:
- part: query
type: replace
mode: single
keys:
- "daemon"
- "upload"
- "dir"
- "execute"
- "download"
- "log"
- "ip"
- "cli"
- "cmd"
# fuzzing openredirects based on parameter name regex
fuzzing:
- part: query
type: replace
mode: single
keys-regex:
- "redirect.*"
# fuzzing ssrf based on parameter value regex
fuzzing:
- part: query
type: replace
mode: single
values:
- "https?://.*"
Fuzz¶
Fuzz specifies the values to replace with a type
for a parameter. It supports payloads, DSL functions, etc and allows users to fully utilize the existing nuclei feature-set for fuzzing purposes.
# fuzz section for xss fuzzing with stop-at-first-match
payloads:
reflection:
- "6842'\"><9967"
stop-at-first-match: true
fuzzing:
- part: query
type: postfix
mode: single
fuzz:
- "{{reflection}}"
# using interactsh-url placeholder for oob testing
payloads:
redirect:
- "{{interactsh-url}}"
fuzzing:
- part: query
type: replace
mode: single
keys:
- "dest"
- "redirect"
- "uri"
fuzz:
- "https://{{redirect}}"
# using template-level variables for SSTI testing
variables:
first: "{{rand_int(10000, 99999)}}"
second: "{{rand_int(10000, 99999)}}"
result: "{{to_number(first)*to_number(second)}}"
http:
...
payloads:
reflection:
- '{{concat("{{", "§first§*§second§", "}}")}}'
fuzzing:
- part: query
type: postfix
mode: multiple
fuzz:
- "{{reflection}}"
Example Fuzzing template¶
An example sample template for fuzzing XSS vulnerabilities is provided below.
id: fuzz-reflection-xss
info:
name: Basic Reflection Potential XSS Detection
author: pdteam
severity: low
http:
- method: GET
path:
- "{{BaseURL}}"
payloads:
reflection:
- "6842'\"><9967"
stop-at-first-match: true
fuzzing:
- part: query
type: postfix
mode: single
fuzz:
- "{{reflection}}"
matchers-condition: and
matchers:
- type: word
part: body
words:
- "{{reflection}}"
- type: word
part: header
words:
- "text/html"
More complete examples are provided here