#VU18066 UNIX symbolic link following in Phusion Passenger - CVE-2017-16355

Vulnerability identifier: #VU18066

Vulnerability risk: Low

CVSSv4.0: 1.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/U:Clear]

CVE-ID: CVE-2017-16355

CWE-ID: CWE-61

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Phusion Passenger
Server applications / Application servers

Vendor: Phusion B.V.

Description

The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists due to a symlink following issue within the agent/Core/SpawningKit/Spawner.h file. A local user can create a specially crafted symbolic link from the REVISION file to an arbitrary file on the system and view contest of arbitrary file through "passenger-status --show=xml" command.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Phusion Passenger: 5.1.0 - 5.1.9

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External links
https://blog.phusion.nl/2017/10/13/passenger-security-advisory-5-1-11/
https://github.com/phusion/passenger/commit/4043718264095cde6623c2cbe8c644541036d7bf
https://seclists.org/bugtraq/2019/Mar/34
https://www.debian.org/security/2019/dsa-4415

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

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.