Documentation - Tutorial

The Pappy (Proxy Attack Proxy ProxY) Proxy is an intercepting proxy for performing web application security testing. Its features are often similar, or straight up rippoffs from Burp Suite. However, Burp Suite is neither open source nor a command line tool, thus making a proxy like Pappy inevitable. The project is still in its early stages, so there are bugs and only the bare minimum features, but it can already do some cool stuff.

I am taking any and all feature requests. If you've used Burp and had any inconvenience with it, tell me about it and I'll do everything in my power to make sure Pappy doesn't have those issues. Or even better, if you want Burp to do something that it doesn't already, let me know so that I can use it to stomp them into the dust improve my project.

If you're brave and want to try and contribute code, please let me know. Right now the codebase is kind of rough and I have refactored it a few times already, but I would be more than happy to find a stable part of the codebase that you can contribute to.

Another option is to try writing a plugin. It might be a bit easier than contributing code and plugins are extremely easy to integrate as a core feature. So you can also contribute by writing a plugin and letting me know about it. You can find out more by looking at the official plugin docs.

Pappy supports OS X and Linux (sorry Windows). Installation requires pip or some other command that can handle a setup.py with requirements. Once the requirements are installed, you can check that it installed correctly by running pappy -l to start the proxy.

$ git clone --recursive https://github.com/roglew/pappy-proxy.git
$ cd pappy-proxy
$ pip install .

Pappy projects take up an entire directory. Any generated scripts, exported responses, plugin data, etc. will be placed in the current directory so it's good to give your project a directory of its own. To start a project, do something like:

$ mkdir test_project
$ cd test_project 
$ pappy
Copying default config to directory
Proxy is listening on port 8000
pappy> exit
$ ls
data.db      project_config.json
$ 

And that's it! The proxy will by default be running on port 8000 and bound to localhost (to keep the hackers out). You can modify the port/interface in config.json. You can list all your intercepted requests with ls, view a full request with vfq <reqid> or view a full response with vfs <reqid>. Right now, the only command to delete requests is filter_prune which deletes all the requests that aren't in the current context (look at the sections on the context/filter strings for more information on that).

If you don't want to dirty up a directory, you can run Pappy in "lite" mode. Pappy will use the default configuration settings and will create a temporary data file in /tmp to use. When you quit, the file will be deleted. If you want to run Pappy in lite mode, run Pappy with either -l or --lite.

Example:

$ pappy -l
Temporary datafile is /tmp/tmpw4mGv2
Proxy is listening on port 8000
pappy> quit
Deleting temporary datafile
$ 

In order for Pappy to view data sent using HTTPS, you need to add a generated CA cert (certificate.crt) to your browser. Certificates are generated using the gencerts command and are by default stored in ~/.pappy/certs. This allows Pappy to act as a CA and sign any HTTPS certificate it wants without the browser complaining. This allows Pappy to decrypt and modify HTTPS requests. The certificate installation instructions are different for each browser.

You can add the CA cert to Firefox by going to Preferences -> Advanced -> View Certificates -> Authorities -> Import and selecting the certificate.crt file in the certs directory.

You can add the CA cert to Chrome by going to Settings -> Show advanced settings -> HTTPS/SSL -> Manage Certificates -> Authorities -> Import and selecting the certificate.crt file in the certs directory.

For Safari (on macs, obviously), you need to add the CA cert to your system keychain. You can do this by double clicking on the CA cert and following the prompts.

I didn't search too hard for instructions on this (since Pappy doesn't support windows) and I don't own a Windows machine to try this, so if you have trouble, I'm not the one to ask. According to Google you can double-click the cert to install it to the system, or you can do Tools -> Content -> Certificates -> Trusted Root Certificates -> Import.

Configuration for each project is done in the config.json file. The file is a JSON-formatted dictionary that contains settings for the proxy. The following fields can be used to configure the proxy:

The following tokens will also be replaced with values:

See the default config.json for examples.

In order to intercept and modify requests to sites that use HTTPS, you have to generate and install CA certs to your browser. You can do this by running the gencerts command in Pappy. By default, certs are stored ~/.pappy/certs. This is also the default location that Pappy will look for certificates (unless you specify otherwise in config.json.) In addition, you can give the gencerts command an argument to have it put the generated certs in a different directory.

The following commands can be used to view requests and responses

The table shown by ls will have the following columns:

You can apply tags to a request and use filters to view specific tags. The following commands can be used to apply and remove tags to requests:

Request IDs are how you identify a request and every command that involves specifying a request will take one or more request IDs. You can see it when you run ls. In addition, you can prepend an ID with prefixes to get requests or responses associated with the request (for example if you modified the request or its response with the interceptor, you can get the unmangled versions.) Here are the valid prefixes:

I know it sounds kind of unintuitive. Here are some example commands that will hopefully make things clearer. Suppose request 1 had its request mangled, and request 2 had its response mangled.

• vfq 1 Prints the mangled version of request 1
• vfq u1 Prints the unmangled version of request 1
• rp u1 Open the repeater with the unmangled version of request 1
• vfs u1 Throws an error because the unmangled version was never submitted
• vfs s1 Throws an error because the response for request 1 was never mangled
• vfs 2 Prints the mangled response of request 2
• vfs s2 Prints the unmangled response of request 2
• vfq u2 Throws an error because request 2's request was never mangled
• vfs u2 Throws an error because request 2's request was never mangled

Some arguments can take multiple IDs for an argument. To pass multiple IDs to a command, separate the IDs with commas (no spaces!). A few examples:

• viq 1,2,u3 View information about requests 1, 2, and the unmangled version of 3
• gma foo 4,5,6 Generate a macro with definitions for requests 4, 5, and 6

The context is a set of filters that define which requests are considered "active". Only requests in the current context are displayed with ls. By default, the context includes every single request that passes through the proxy. You can limit down the current context by applying filters. Filters apply rules such as "the response code must equal 500" or "the host must contain google.com". Once you apply one or more filters, only requests/responses which pass every active filter will be a part of the current context.

Filter strings define a condition that a request/response pair must pass to be part of the context. Most filter strings have the following format:

<field> <comparer> <value>

Where <field> is some part of the request/response, <comparer> is some comparison to <value>. For example, if you wanted a filter that only matches requests to target.org, you could use the following filter string:

host is target.org

field = "host"
comparer = "is"
value = "target.org"

Also if you prefix a comparer with 'n' it turns it into a negation. Using the previous example, the following will match any request except for ones where the host contains target.org:

host nis target.org

field = "host"
comparer = "nis"
value = "target.org"

For fields that are a list of key/value pairs (headers, get params, post params, and cookies) you can use the following format:

<field> <comparer1> <value1>[ <comparer2> <value2>]

This is a little more complicated. If you don't give comparer2/value2, the filter will pass any pair where the key or the value matches comparer1 and value1. If you do give comparer2/value2, the key must match comparer1/value1 and the value must match comparer2/value2 For example:

Filter A:
    cookie contains Session

Filter B:
    cookie contains Session contains 456

Filter C:
    cookie ncontains Ultra

Cookie: SuperSession=abc123
Matches A and C but not B

Cookie: UltraSession=abc123456
Matches both A and B but not C

A few filters don't conform to the field, comparer, value format. You can still negate these.

Scope is a set of rules to define whether Pappy should mess with a request. You define the scope by setting the context to what you want the scope to be and running scope_save. The scope is saved in the data file and is automatically restored when using the same project directory.

Any requests which don't match all the filters in the scope will be passed straight to the browser and will not be caught by the interceptor or recorded in the data file. This is useful to make sure you don't accidentally do something like log in to your email through the proxy and have your plaintext username/password stored.

Pappy also includes some built in filters that you can apply. These are things that you may want to filter by but may be too tedius to type out. The fbi command also supports tab completion.

This feature is like Burp's proxy with "Intercept Mode" turned on, except it's not turned on unless you explicitly turn it on. When the proxy gets a request while in intercept mode, it lets you edit it before forwarding it to the server. In addition, it can stop responses from the server and let you edit them before they get forwarded to the browser. When you run the command, you can pass req and/or rsp as arguments to say whether you would like to intercept requests and/or responses. Only in-scope requests/responses will be intercepted (see Scope section).

The interceptor will use your EDITOR variable to decide which editor to edit the request/response with. If no editor variable is set, it will default to vi.

To forward a request, edit it, save the file, then quit.

Intercept both requests and responses:
> ic requests responses
> ic req rsp

Intercept just requests:
> ic requests
> ic req

Intercept just responses:
> ic responses
> ic rsp

Be totally useless:
> ic

To drop a request, delete everything, save and quit.

This feature is like Burp's repeater (yes, really). You choose a request and Pappy will open vim in a split window with your request on the left and the original response on the right. You can make changes to the request and then run ":RepeaterSubmitBuffer" to submit the modified request. The response will be displayed on the right. This command is bound to <leader>f by default, but you can bind it to something else too in your vimrc (I think, dunno if vim will complain if the function undefined which it will be for regular files). This command will submit whatever buffer your cursor is in, so make sure it's in the request buffer.

When you're done with repeater, run ":qa!" to avoid having to save changes to nonexistent files.

Macros are Pappy's version of Burp's intruder. You can use macros to make automated requests through the proxy and save them to the data file. A macro file is any python script file in the current directory that is in the form macro_<name>.py. An example project directory with macros would be:

$ ls -l
-rw-r--r-- 1 scaryhacker wheel     150 Nov 26 11:17 config.json
-rw------- 1 scaryhacker wheel 2639872 Nov 26 17:18 data.db
-rw-r--r-- 1 scaryhacker wheel     471 Nov 26 18:42 macro_blank.py
-rw-r--r-- 1 scaryhacker wheel     264 Nov 26 18:49 macro_hackthensa.py
-rw-r--r-- 1 scaryhacker wheel    1261 Nov 26 18:37 macro_testgen.py
-rw-r--r-- 1 scaryhacker wheel     241 Nov 26 17:18 macro_test.py

In this case we have a blank, hackthensa, testgen, and test macro. A macro script is any python script that defines a run_macro(args) function and a MACRO_NAME variable. For example, a simple macro would be:

### macro_print.py

MACRO_NAME = 'Print Macro'

def run_macro(args):
    if args:
        print "Hello, %s!" % args[0]
    else:
        print "Hello, Pappy!"

You can place this macro in your project directory then load and run it from Pappy. When a macro is run, arguments are passed from the command line. Arguments are separated the same way as they are on the command line, so if you want to use spaces in your argument, you have to put quotes around it.

$ pappy
Proxy is listening on port 8000
pappy> lma
Loaded "<Macro Test Macro (tm/test)>"
Loaded "<Macro Macro 6494496 (testgen)>"
Loaded "<Macro Print Macro (print)>"
Loaded "<Macro Hack the NSA (htnsa/hackthensa)>"
Loaded "<Macro Macro 62449408 (blank)>"
pappy> rma print
Hello, Pappy!
pappy> rma print NSA
Hello, NSA!
pappy> rma print Idiot Slayer
Hello, Idiot!
pappy> rma print "Idiot Slayer"
Hello, Idiot Slayer!

You'll need to run lma every time you make a change to the macro in order to reload it. In addition, any code outside of the run_macro function will be run when it the macro gets loaded.

You can also generate macros that have Pappy Request objects created with the same information as requests you've already made. For example:

$ pappy
Proxy is listening on port 8000
pappy> ls
ID  Verb  Host         Path               S-Code  Req Len  Rsp Len  Time  Mngl
5   GET   vitaly.sexy  /esr1.jpg          200 OK  0        17653    --    --
4   GET   vitaly.sexy  /netscape.gif      200 OK  0        1135     --    --
3   GET   vitaly.sexy  /construction.gif  200 OK  0        28366    --    --
2   GET   vitaly.sexy  /vitaly2.jpg       200 OK  0        2034003  --    --
1   GET   vitaly.sexy  /                  200 OK  0        1201     --    --
pappy> gma sexy 1
Wrote script to macro_sexy.py
pappy> quit
$ cat macro_sexy.py
from pappyproxy.http import Request, get_request, post_request

MACRO_NAME = 'Macro 94664581'
SHORT_NAME = ''

###########
## Requests

req0 = Request((
'GET / HTTP/1.1\r\n'
'Host: vitaly.sexy\r\n'
'User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:36.0) Gecko/20100101 Firefox/36.0\r\n'
'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n'
'Accept-Language: en-US,en;q=0.5\r\n'
'Accept-Encoding: gzip, deflate\r\n'
'Connection: keep-alive\r\n'
'Pragma: no-cache\r\n'
'Cache-Control: no-cache\r\n'
'\r\n'
))


def run_macro(args):
    # Example:
    # req = req0.copy() # Copy req0
    # req.submit() # Submit the request to get a response
    # print req.response.raw_headers # print the response headers
    # req.save() # save the request to the data file
    # or copy req0 into a loop and use string substitution to automate requests
    pass

If you enter in a value for SHORT_NAME, you can use it as a shortcut to run that macro. So if in a macro you set SHORT_NAME='tm' you can run it by running pappy> rma tm.

The main method of interacting with the proxy is through Request objects. You can submit a request with req.sumbit() and save it to the data file with req.save(). The objects also have attributes which can be used to modify the request in a high-level way. You can see the full documentation for more details on using these objects.

Dict-like objects are represented with a custom class called a RepeatableDict. Again, look at the docs for details. For the most part, you can interact with it like a normal dictionary, but don't be surprised if it's missing some methods you would expect.

Here is a quick list of attributes that you can use with Request objects:

Request methods:

And here is a quick list of attributes that you can use with Response objects:

Like I said, these interfaces are prone to change and will probably crash when you use them. If you get a traceback, send me an email so I can fix it.

There are also a few functions which could be useful for creating requests in macros. It's worth pointing out that request_by_id is useful for passing request objects as arguments. For example, here is a macro that lets you resubmit a request with the Google Bot user agent:

## macro_googlebot.py

from pappyproxy.http import Request, get_request, post_request, request_by_id
from pappyproxy.context import set_tag
from pappyproxy.iter import *

MACRO_NAME = 'Submit as Google'
SHORT_NAME = ''

def run_macro(args):
    req = request_by_id(args[0])
    req.headers['User-Agent'] = "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"
    req.submit()
    req.save()

Intercepting macros let you mangle requests as they pass through the proxy. Similarly to normal macros, an intercepting macro is any python script with an "int" prefix. For example, int_name.py would be a valid intercepting macro name. They are also loaded with the lma command. An intercepting macro can define two functions: mangle_request or mangle_response. Both requests only take a Request object as a parameter. mangle_request returns either a new, modified Request object to change it, or it can return the original object to not mangle it. The mange_response must return a Response (not request!) object. The request passed in to mangle_response will have an associated response with it. If you want to modify the response, copy request.response, make modifications, then return it. If you would like to pass it through untouched, just return request.response.

Note, that due to twisted funkyness, you cannot save requests from intercepting macros. Technically you can, but to do that you'll have to define async_mangle_request (or response) instead of mangle_request (or response) then use Request.async_deep_save which generates a deferred, then generate a deferred from async_mangle_requests (inline callbacks work too). If you've never used twisted before, please don't try. Twisted is hard. Plus the mangled request will be saved before it is submitted anyways.

Confusing? Here are some example intercepting macros:

## int_cloud2butt.py

import string

MACRO_NAME = 'Cloud to Butt'

def mangle_response(request):
    r = request.response.copy()
    r.raw_data = string.replace(r.raw_data, 'cloud', 'butt')
    r.raw_data = string.replace(r.raw_data, 'Cloud', 'Butt')
    return r

## int_donothing.py

import string

MACRO_NAME = 'Do Nothing'

def mangle_request(request):
    return request

def mangle_response(request):
    return request.response

## int_adminplz.py

from base64 import base64encode as b64e

MACRO_NAME = 'Admin Session'

def mangle_request(request):
    r = request.copy()
    r.headers['Authorization'] = 'Basic %s' % b64e('Admin:Password123')
    return r

In addition, you can use an init(args) function to get arguments from the command line. If no arguments are passed, args will be an empty list. Here is an example macro that does a search and replace:

## int_replace.py

MACRO_NAME = 'Find and Replace'
SHORT_NAME = ''
runargs = []

def init(args):
    global runargs
    runargs = args

def mangle_request(request):
    global runargs
    if len(runargs) < 2:
        return request
    request.body = request.body.replace(runargs[0], runargs[1])
    return request

def mangle_response(request):
    global runargs
    if len(runargs) < 2:
        return request.response
    request.response.body = request.response.body.replace(runargs[0], runargs[1])
    return request.response

You can use this macro to do any search and replace that you want. For example, if you wanted to replace "Google" with "Skynet", you can run the macro like this:

pappy> lma
Loaded "<InterceptingMacro Find and Replace (replace)>"
pappy> rim replace Google Skynet
"Find and Replace" started
pappy> 

Now every site that you visit will be a little bit more accurate.

You can use the following commands to start/stop intercepting macros

You can watch in real-time what requests are going through the proxy. Verbosisty defaults to 1 which just states when connections are made/lost and some information on what is happening. If verbosity is set to 3, it includes all the data which is sent through the proxy and processed. It will print the raw response from the server, what it decodes it to, etc. Even if you don't run this command, all the information is stored in the dubug directory (the directory is cleared every start though!)

This is a list of other random stuff you can do that isn't categorized under anything else. These are mostly commands that I found that I needed while doing a test and just added. They likely don't do a ton of error checking.

If you don't have any intercepting macros running, Pappy will forward data to the browser as it gets it. However, if you're trying to mangle messages/responses, Pappy will need to download the entire message first.

Note that this section is a very quick overview of plugins. For a full description of how to write them, please see the official docs.

It is also possible to write plugins which are reusable across projects. Plugins are simply Python scripts located in ~/.pappy/plugins. Plugins are able to create new console commands and maintain state throughout a Pappy session. They can access the same API as macros, but the plugin system is designed to allow you to create general purpose commands as compared to macros which are meant to be project-specific scripts. Still, it may not be a bad idea to try building a macro to do something in a quick and dirty way before writing a plugin since plugins are more complicated to write.

A simple hello world plugin could be something like:

## hello.py
import shlex

def hello_world(line):
    if line:
        args = shlex.split(line)
        print 'Hello, %s!' % (', '.join(args))
    else:
        print "Hello, world!"

###############
## Plugin hooks

def load_cmds(cmd):
    cmd.set_cmds({
        'hello': (hello_world, None),
    })
    cmd.add_aliases([
        ('hello', 'hlo'),
        ('hello', 'ho'),
    ])

You can also create commands which support autocomplete:

import shlex

_AUTOCOMPLETE_NAMES = ['alice', 'allie', 'sarah', 'mallory', 'slagathor']

def hello_world(line):
    if line:
        args = shlex.split(line)
        print 'Hello, %s!' % (', '.join(args))
    else:
        print "Hello, world!"
        
def complete_hello_world(text, line, begidx, endidx):
    return [n for n in _AUTOCOMPLETE_NAMES if n.startswith(text)]
        
###############
## Plugin hooks

def load_cmds(cmd):
    cmd.set_cmds({
        'hello': (hello_world, complete_hello_world),
    })
    cmd.add_aliases([
        ('hello', 'hlo'),
    ])

Then when you run Pappy you can use the hello command:

$ pappy -l
Temporary datafile is /tmp/tmpBOXyJ3
Proxy is listening on port 8000
pappy> ho
Hello, world!
pappy> ho foo bar baz
Hello, foo, bar, baz!
pappy> ho foo bar "baz lihtyur"
Hello, foo, bar, baz lihtyur!
pappy>

A lot of the time, you can get away with writing a macro. However, you may consider writing a plugin if:

• You find yourself copying one macro to multiple projects
• You want to write a general tool that can be applied to any website
• You need to maintain state during the Pappy session

My guess is that if you need one quick thing for a project, you're better off writing a macro first and seeing if you end up using it in future projects. Then if you find yourself needing it a lot, write a plugin for it. You may also consider keeping a mine.py plugin where you can write out commands that you use regularly but may not be worth creating a dedicated plugin for.

There are some settings that apply to Pappy as a whole and are stored in ~/.pappy/global_config.json. These settings are generally for tuning performance or modifying behavior on a system-wide level. No information about projects is put in here since it is world readable. You can technically add settings in here for plugins that you write, but if it's at all possible, please keep settings in the normal project config.

Settings included in ~/.pappy/global_config.json:

Yes! If you don't want to go completely over to Pappy yet, you can configure Burp to use Pappy as an upstream proxy server. That way, traffic will go through both Burp and Pappy and you can use whichever you want to do your testing.

How to have Burp forward traffic through Pappy:

1. Open Burp
2. Go to Options -> Connections -> Upstream Proxy Servers
3. Click Add
4. Leave Destination Host blank, but put 127.0.0.1 in Proxy Host and 8000 into Port (assuming you're using the default listener)
5. Configure your browser to use Burp as a proxy

You can't do anything with a request/response until it is decoded and saved to disk. In between the time when a request is decoded and when it's saved to disk, it will have an ID of --. So just wait a little bit and it will get an ID you can use.

I do some stuff to try and keep speed and memory usage to reasonable levels. Unfortunately, things might seem slow in some areas. This is where I try and explain why those exist. Honestly, you probably don't care about this, but I'd rather have it written down and have nobody read it than just leave people in the dark.

For performance reasons, Pappy by default will not store every request in memory. The cache will store a certain number of the most recently accessed requests in memory. This means that if you go through all of history, it could be slow (for example running ls a or sm). If you have enough RAM to keep everything in memory, you can set the request cache size to -1 to just keep everything in memory. However, even if the cache size is unlimited, it still won't load a request into memory untill you access it. So if you want to load everything in memory, run ls a.

By default, Pappy will cache 2000 requests. This is kind of heavy, but it's assumed you're doing testing on a reasonably specced laptop. Personally, I live on the edge and use -1 until I run into memory issues.

The boring part of the readme

• 0.2.1
  • Improve memory usage
  • Tweaked plugin API
• 0.2.0
  • Lots of refactoring
  • Plugins
  • Bugfixes probably
  • Change prompt to make Pappy look more professional (but it will always be pappy time in your heart, I promise)
  • Create changelog
  • Add response streaming if no intercepting macros are active
• 0.1.1
  • Start using sane versioning system
  • Did proxy things