URL redirection in curl (Alpine package)

1) URL redirection

EUVDB-ID: #VU1144

Risk: Low

CVSSv3.1: 4.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N/E:P/RL:O/RC:C]

CVE-ID: CVE-2016-8624

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform phishing attacks.

The vulnerability is caused by an error when parsing URL. A remote attacker can supply a link with ending "#" character in hostname and cause libcurl client to redirect to a host, specified after the "#" character.

Exploit example:

http://example.com#@evilsite.com/1.txt

The above URL will force libcurl client to connect to evilsite.com hostname instead of example.com.

The vulnerability allows an attacker to perform phishing attacks by tricking victims to connect to untrusted host.

Mitigation

Install update from vendor's website.

Vulnerable software versions

curl (Alpine package): 7.49.1-r3

External links

http://git.alpinelinux.org/aports/commit/?id=e57c1f8b95e9a6aecc75e9eaae6c7bf9e259adb6
http://git.alpinelinux.org/aports/commit/?id=7079fe21530ae1c8147925d8b591131b786ab2e9
http://git.alpinelinux.org/aports/commit/?id=619d9f8608068fab555a9a54e6154eb798eb5c2c
http://git.alpinelinux.org/aports/commit/?id=39696e7a1a7079578ea07cb9514fd0c50105340e
http://git.alpinelinux.org/aports/commit/?id=ba3dc3d210189d8b88c35c3b6850f54f8041f3fa
http://git.alpinelinux.org/aports/commit/?id=4cbdd0cf8c1d0c855e0d3cfb56ef02aa19716a01
http://git.alpinelinux.org/aports/commit/?id=41621bfa2c8cbc7303191ddefd9ccaa650d8b359
http://git.alpinelinux.org/aports/commit/?id=ffe6b82496f728d1d75dae4030047c6ff48a9c5a

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.