GHSA-5pq7-52mg-hr42: httparty has multipart/form-data request tampering vulnerability
ImpactI found "multipart/form-data request tampering vulnerability" caused by Content-Disposition "filename" lack of escaping in httparty.`httparty/lib/httparty/request` > `body.rb` > `def generate_multipart`https://github.com/jnunemaker/httparty/blob/4416141d37fd71bdba4f37589ec265f55aa446ce/lib/httparty/request/body.rb#L43By exploiting this problem, the following attacks are possibleAn attack that rewrites the "name" field according to the crafted file name, impersonating (overwriting) another field.Attacks that rewrite the filename extension at the time multipart/form-data is generated by tampering with the filenameFor example, this vulnerability can be exploited to generate the following Content-Disposition.Normal Request example:
normal input filename: `abc.txt`generated normal header in multipart/form-data
`Content-Disposition: form-data; name="avatar"; filename="abc.txt"`Malicious Request example
malicious input filename: `overwrite_name_field_and_extension.sh"; name="foo"; dummy=".txt`generated malicious header in multipart/form-data:
`Content-Disposition: form-data; name="avatar"; filename="overwrite_name_field_and_extension.sh"; name="foo"; dummy=".txt"`The Abused Header has multiple name ( `avatar` & `foo` ) fields and the "filename" has been rewritten from `*.txt` to `*.sh` .These problems can result in successful or unsuccessful attacks, depending on the behavior of the parser receiving the request.
I have confirmed that the attack succeeds, at least in the following frameworksSpring (Java)Ktor (Kotlin)Ruby on Rails (Ruby)The cause of this problem is the lack of escaping of the `"` (Double-Quote) character in Content-Disposition > filename.WhatWG's HTML spec has an escaping requirement.https://html.spec.whatwg.org/#multipart-form-dataFor field names and filenames for file fields, the result of the encoding in the previous bullet point must be escaped by replacing any 0x0A (LF) bytes with the byte sequence `%0A`, 0x0D (CR) with `%0D` and 0x22 (") with `%22`. The user agent must not perform any other escapes.PatchesAs noted at the beginning of this section, encoding must be done as described in the HTML Spec.https://html.spec.whatwg.org/#multipart-form-dataFor field names and filenames for file fields, the result of the encoding in the previous bullet point must be escaped by replacing any 0x0A (LF) bytes with the byte sequence `%0A`, 0x0D (CR) with `%0D` and 0x22 (") with `%22`. The user agent must not perform any other escapes.Therefore, it is recommended that Content-Disposition be modified by either of the followingBefore:
`Content-Disposition: attachment;filename="malicious.sh";dummy=.txt`After:
`Content-Disposition: attachment;filename="%22malicious.sh%22;dummy=.txt"`https://github.com/jnunemaker/httparty/blob/4416141d37fd71bdba4f37589ec265f55aa446ce/lib/httparty/request/body.rb#L43Also, as for `\r`, `\n`, URL Encode is not done, but it is not newlines, so it seemed to be OK.
However, since there may be omissions, it is safer to URL encode these as well, if possible.
( `\r` to `%0A` and `\d` to `%0D` )PoCPoC EnvironmentOS: macOS Monterey(12.3)
Ruby ver: ruby 3.1.2p20 
httparty ver: 0.20.0
(Python3 - HTTP Request Logging Server)PoC procedure(Linux or MacOS is required. 
This is because Windows does not allow file names containing `"` (double-quote) .)Create ProjectCreate malicious fileGenerate Vuln codeRun Logging ServerI write Python code, but any method will work as long as you can see the HTTP Request Body.
(e.g. Debugger, HTTP Logging Server, Packet Capture)$ vi logging.py$ python logging.pyRun & Logging serverReturn Request Header & Body:User-Agent: Ruby
Content-Type: multipart/form-data; boundary=------------------------F857UcxRc2J1zFOz
Connection: close
Host: localhost:12345
Content-Length: 457--------------------------F857UcxRc2J1zFOz
Content-Disposition: form-data; name="name"Foo Bar
--------------------------F857UcxRc2J1zFOz
Content-Disposition: form-data; name="email"example@email.com
--------------------------F857UcxRc2J1zFOz
Content-Disposition: form-data; name="avatar"; filename="overwrite_name_field_and_extension.sh"; name="foo"; dummy=".txt"
Content-Type: text/plainabc
--------------------------F857UcxRc2J1zFOz--Content-Disposition:Content-Disposition: form-data; name="avatar"; filename="overwrite_name_field_and_extension.sh"; name="foo"; dummy=".txt"name fields is duplicate (avator & foo)filename & extension tampering ( .txt --> .sh )ReferencesI also include a similar report that I previously reported to Firefox.
https://bugzilla.mozilla.org/show_bug.cgi?id=1556711I will post some examples of frameworks that did not have problems as reference.Golang
https://github.com/golang/go/blob/e0e0c8fe9881bbbfe689ad94ca5dddbb252e4233/src/mime/multipart/writer.go#L144Spring
https://github.com/spring-projects/spring-framework/blob/4cc91e46b210b4e4e7ed182f93994511391b54ed/spring-web/src/main/java/org/springframework/http/ContentDisposition.java#L259-L267Symphony
https://github.com/symfony/symfony/blob/123b1651c4a7e219ba59074441badfac65525efe/src/Symfony/Component/Mime/Header/ParameterizedHeader.php#L128-L133For more informationIf you have any questions or comments about this advisory:Email us at [kumagoro_alice@yahoo.co.jp](mailto:kumagoro_alice@yahoo.co.jp)
CVSS v3.1: 6.5