OS Command Injection in Shadowsocks Shadowsocks-libev

1) OS Command Injection

EUVDB-ID: #VU38010

Risk: Low

CVSSv3.1: 6.8 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-15924

CWE-ID: CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Exploit availability: No

Description

The vulnerability allows a local authenticated user to execute arbitrary code.

In manager.c in ss-manager in shadowsocks-libev 3.1.0, improper parsing allows command injection via shell metacharacters in a JSON configuration request received via 127.0.0.1 UDP traffic, related to the add_server, build_config, and construct_command_line functions.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Shadowsocks-libev: 1.3 - 3.1.0

Debian Linux: 1.3 - 9.2

External links

http://openwall.com/lists/oss-security/2017/10/13/2
http://www.debian.org/security/2017/dsa-4009
http://github.com/shadowsocks/shadowsocks-libev/commit/c67d275803dc6ea22c558d06b1f7ba9f94cd8de3
http://github.com/shadowsocks/shadowsocks-libev/issues/1734
http://www.x41-dsec.de/lab/advisories/x41-2017-010-shadowsocks-libev/

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.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

The attacker would have to login to the system and perform certain actions in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.