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What is FTP Spoofing Attack?

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FTP stands for file transfer protocol and it is an application layer protocol for transferring files between a client and a server. We can download, delete, move, rename, and copy files to a server using an FTP client. If you transfer a file using FTP, it will mostly upload or download data from the FTP server. When the files are uploaded, they are transferred from the personal computer to the server, and when files are downloaded, they get transferred from the server to the personal computer.

Spoofing:

Spoofing is a kind of cyber attack in which an intruder impersonates another legitimate device or user in order to initiate a network attack. To put it another way, an attacker sends a communication from a device that appears to be real.

FTP Spoofing Attack:

Usually, in FTP servers, external users or IPs other their organization IPs will be blocked to avoid logon or to access/transfer files by an adversary.  Even though there are more security measures,  attackers could use an external computer to assume the host address of a computer on the company network and download files during data transfer.  

Working:

  1. Attackers will fetch the server’s user name and password via a brute force attack to get into the server to get the files or to transfer the payload.
  2. Even though attackers have passwords in their hands, most of the organizations will drop/reject the connections from external IPs.
  3. So attackers will hide their original identity by changing the local IP into the organization’s IP address. It is possible to spoof private IP addresses with some significant limitations.
  4. It may be possible to establish a connection that can be used to transfer a payload to the target by using IP spoofing, but it will not be possible to establish a true two-way TCP connection.
  5. For instance, the attacker can get the target machine to respond, but the responses from the attacker machine will not be routed to them, therefore they will not receive them.
  6. As a result, UDP connections are more widely utilized for IP spoofing than TCP connections. The attacker, on the other hand, can imitate receiving the packets by sending back bogus acknowledgement packets and then proceed to transmit a payload or establish a connection into the internal system.
  7. It’s extremely tough to hack because it may not be viable on all systems due to variations in how different platforms handle TCP connections, making it more difficult for the attacker to replicate ack packets.

Working of  FTP Spoofing Attack

Detection Method:

  1. IP address spoofing is detected by scanning data packet headers for discrepancies. The IP address can be validated by its MAC (Media Access Control) address or by a security system like Cisco’s IOS NetFlow, which assigns an ID and timestamp to each computer that accesses the network. So at the first stage itself, it will get failed if the MAC address does not belong to the organization domain.
  2. Each BotNet contains potentially thousands of computers capable of reaching multiple IP addresses. Thus, the automatic attack is difficult to trace.

Preventive Measures:

  1. Use a good firewall to analyze every packet to avoid connection from external IP.
  2. Use strong passwords to avoid the initial stage of an FTP attack.
  3. Limit FTP server access to just necessary administrative professionals, and compel staff with credentials to use multi-factor authentication to reduce this threat. Passcodes that must be kept should be kept in an AD domain or on an LDAP server.
  4. When used independently, FTPS techniques are insecure. Clients do not need to request encryption to connect to the network. Only when the client expressly demands a secure connection is it possible. On the network, this feature should never be enabled. Instead, use implicit encryption, which forces all connections to be encrypted. The SSL and TLS 1.0 protocols are no longer supported, so the file server should be running TLS version 1.2.
  5. The standard FTP protocol has been deprecated. Secure file transfer protocol servers, work via a secure connection to keep your company and customers safe.
  6. Nowadays, hash algorithms become more vulnerable to brute force attacks. Blowfish and ciphers are both obsolete and easily cracked. The Advanced Encryption Standard (AES) should be used in the network. To protect the integrity of the data transmissions, use algorithms from the SHA-2 family.
  7. Attacks that cause a denial of service (DoS) are still widespread. Programming the FTP or SFTP server to restrict malicious IP addresses is time-consuming, but it is still one of the most effective defenses against these attacks. We can also use allow lists to explicitly accept clients on your network, but this only works for the few traffic sources that still employ static IP addresses.
  8. By misusing file permission access, hackers can take advantage of our system. Clients should never be given exclusive access to a whole directory, even if they need permission to upload or download data. Any files that aren’t being used on a DMZ server should be encrypted. Files on an FTP server should only be kept for as long as they are required.

Conclusion:

FTP is used widely in organizations for file sharing, so it’s like candy in the mouth for the attackers. Organizations should take necessary actions and security measures to prevent FTP attacks.  


Last Updated : 08 Aug, 2022
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