INTRODUCTION- Short Message Peer-to-Peer, or SMPP, is a protocol that the telecommunications sector uses to send and receive SMS messages over the Internet, primarily between Short Message Service Centers. SMS messages can be delivered quickly thanks to the protocol, which is a level-7 TCP/IP protocol. This software is the backbone for sending SMS messages over an Internet network. The SMPP server uses the SMPP protocol for SMS sending and receiving.
What is SMPP used for?
The Short Message Peer Protocol (SMPP) is the most extensively used method for sending SMS messages over the Internet. SMPP security is frequently used to give value-added SMS content services, such as mobile banking, payment reminders, SOS calls, stock and news notifications, train and flight inquiries, and so on. These communications contain sensitive information that must be safeguarded.
The SMPP protocol is an application layer that conveys messages over TCP/IP connections. The SMPP protocol has no security by default. Eavesdroppers can intercept the data because it goes across the Internet in an unencrypted state.
Transport Layer Security can provide security for the SMPP security protocol (TLS). The TLS protocol layer sits between the SMPP security protocol and the TCP/IP protocol stack. The protocol stack is built from the following layers if it is installed:
● TLS/SSL layer
● SMPP layer
● TCP layer
● IP layer
Is SMPP secure?
The fundamental transport interface between the SMSC and ESME is based on a TCP/IP or X.25 network connection. SMPP is an application layer protocol not intended to provide transport functions. Therefore, the underlying network connection is assumed to provide reliable data transfer from point to point, including packet encoding, windowing, flow control, and error management. SMS is always a good idea in general. At the wireless telecommunications layer, However, SMPP protocol exploits are limited at the TCP/IP layer. Some SMPP flaws can result in Silent SMS, resulting in no mobile phone alert.
SMPP does not define any security method for exchanging messages between the external SMSE and the SMSC at the application layer.
The vulnerabilities discovered in the SMPP Security are mentioned below.
● No Confidentiality: Because SMPP does not include an encryption standard, messages sent from ESME to SMSC via SMPP are sent in plain text. The information carried out by the SMPP protocol can be easily accessed using tools such as Wireshark and Snort. ESME transmits the system id and password to SMSC during the binding process to authenticate itself. Using Wireshark, this information is quickly hacked, and the connection's secrecy is easily exposed. The client account on the server is stored in plain text.
● Man-in-the-middle Attack: The attacker can establish independent connections with the victims and relay messages between them, giving the impression that they communicate directly over a secure channel.
The attacker must be able to intercept all messages sent between the two victims and insert new ones into the connection. In contrast, the entire conversation is controlled by the attacker8.
● Message Tampering: The deliberate alteration or adulteration of protocol information is possible. This could result in SMS messages being altered before they reach their intended receivers
● No Endpoint Authentication: Because there is no confidentiality, attackers can readily compromise the SMSC's login credentials. The attacker can use the messaging services after authenticating himself as a user.
Does SMPP support TLS?
Transport Layer Security (TLS) is a cryptographic system that secures communications over networks like the Internet. TLS is an IETF standards track protocol defined in RFC 5246 based on the Netscape Corporation-created older SSL protocols. TLS allows client/server programs to communicate across a network in a way that prevents eavesdropping and tampering. TLS uses cryptography to offer endpoint authentication and communication confidentiality over the Internet. TLS employs a public-and-private key encryption method, as well as the use of a digital certificate.
TLS communication begins with an information exchange between the client and the server. The TLS handshake refers to this information exchange. The TLS handshake serves three primary functions. Agreeing on encryption procedures, you can negotiate the cipher suite, authenticate identity, and establish information security.
● Dealing with the Cipher Suite: The TLS session begins with the client and server negotiating which encryption suite will be used. A cipher suite is a collection of cryptographic methods and key sizes that a computer can use to encrypt data. The cipher suite contains information on public key exchange techniques, secret key encryption algorithms, and available cryptographic hash functions.
● Authenticating the Server: Authenticating the server ensures that the server is the entity that the client believes it is. To demonstrate that a server belongs to the organization it claims to belong to, the server then displays its public key certificate to the client. The client can be confident in the server's identity if the certificate is valid. The client and server exchange details to decide on the same secret key. With RSA, for example, the client encrypts the secret key information using the server's public key, which is retrieved through the public key certificate. The client provides the server with encrypted secret key information. Only the server can decrypt this message since it requires its private key.
● Encrypted Data Transmission: The client and server now use the same secret key. They attach a Hash-based Message Authentication to each message using the cryptographic hash function chosen in the first step of this process and share secret information. They then encrypt the safe data and the HMAC using the secret key and the secret key algorithm agreed upon in the first step of this process. The client and server can communicate safely with their encrypted and hashed data.
● Confidentiality and Privacy: Cryptography protects the sensitive information that ESME sends to SMSC. SMPP PDUs are encrypted and converted to cipher text. The encrypted text is meaningless to anyone who might eavesdrop and intercept the transmission. It is anticipated that brute force alone would take millions of years to decipher the ciphertext. A key is information that converts a plaintext message into an encrypted cipher text message.
● Message Authenticity: When ESME delivers a PDU to SMSC, the PDU could be intercepted, altered, and sent on its way. The encrypted PDU is sent with a message digest to ensure message integrity. A message digest is a fixed-length PDU representation. The SMSC recalculates the digest based on the PDU and compares it to the digest attached to the PDU when the message arrives. If the values don't match, the PDU is corrupted and won't be processed. TLS resolves the issue of message tampering in this case.
● Authentication: ESME must authenticate SMSC to ensure that the server is not fraudulent. Digital certificates are used to authenticate users in this case. During the TLS handshaking operation, SMSC provides ESME with a digital certificate copy. A digital certificate is a digital document. A copy of SMSC's public key is contained within that certificate. Information about the domain's owner (domain name, organization name, location, and so on). A trusted third-party Certificate Authority, such as VeriSign, verifies or "signs" the TLS certificate. The problem of endpoint authentication is overcome by employing digital certificates in the TLS protocol.
Conclusion
SMS security has become critical in today's rapidly evolving telecommunications landscape. SMS generated by computers utilizing the SMPP security protocol must be safeguarded from outside intruders. The SMPP protocol, which can transfer messages in bulk, is made secure by including Transport Layer Security. Secure SMPP can meet the security requirements of secrecy, integrity, and authentication.
Secgen is a telecom lead company focused on securing the connections built while communication is established. The expertise team is working on providing safe and secure SMS telecommunication.
To deliver secure communications to SMSC, a simple Secured SMPP protocol-based client tool is built. Sending secure messages using the Secure SMPP protocol incurs a slight speed overhead when compared to the standard SMPP protocol. Secure SMPP is simple to integrate into application servers in banking and other businesses.
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