Security Issues in Transport Layer

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Security issues in Transport Layer

Abdul Kalam Azad

12-1-5-008

April 16, 2016

1 IntroductionTransport layer is a protocol for host-to-host communication. Transportlayer must ensure to protect data when it is being transmitted.

Transport layer is the first layer of the TCP/IP model that offers relia-bility. Hence, transport layer security is an important subject.

Most common example of security issue in transport layer is Portscanattack, which operates under the assumption that target host is compliantwith Transmission Control Protocol.

2 Security In Transport Layer

Currently, security needed in transport layer, viz. encryption, authentica-tion, and data integrity, is provided by two protocols: SSL and TLS

2.1 SSL

SSL or Secure Socket Layer protocol was originally developed at Netscapeto enable ecommerce transaction security on the Web

2.2 TLS

TLS (Transport Layer Security) is an updated, more secure, version of SSL.SSL 3.1 is renamed to TLS 1.0 by IETF. SSL and TLS are only applicablein TCP protocol. For UDP protocol, DTLS or Datagram Transport LayerSecurity is used.Since, TLS and SSL are not interoperable, both are mentioned separately.

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3 Insufficient Transport Layer Security

Poor applications leads to insufficient transport layer security, [1] wherenot all traffic flowing between two endpoints is properly secured, whichmakes it possible for attackers to perform man-in-the-middle attacks, e.g.IP spoofing.

4 Known Attacks on TLS [2]

4.1 SSL Stripping

Various attacks attempt to remove the use of (SSL/TLS) altogether by mod-

ifying unencrypted protocols that request the use of TLS, specifically mod-ifying HTTP traffic and HTML pages as they pass through the media.

4.2 STARTTLS Command Injection Attack

This is a software flaw where an attacker injects client commands duringthe unprotected connection which are stored in buffer, such that commandsreceived prior to TLS negotiation are executed after TLS negotiation.

4.3 BEAST attack

The BEAST attack [BEAST] uses issues with the TLS 1.0 implementation of

Cipher Block Chaining (CBC) to decrypt parts of a packet, and specificallyto decrypt HTTP cookies when HTTP is run over TLS.

4.4 Padding Oracle Attacks

In cryptography, variable-length plaintext messages often have to be padded(expanded) to be compatible with the underlying cryptographic primitive.Padding Oracle Attack is performed by guessing whether a message is cor-rectly padded or not.

4.5 Attacks on RC4

The RC4 algorithm has been used with TLS. Recent cryptanalysis resultsexploit biases in the RC4 keystream to recover repeatedly encrypted plain-texts.

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4.6 Compression Attacks: CRIME, TIME, and BREACH

These vulnerabilities are a result of inadvertent information leakage throughdata compression used over TLS

4.7 Theft of RSA Private Keys

When TLS is used with most non-Diffie-Hellman cipher suites, it is sufficientto obtain the server’s private key in order to decrypt any sessions (past andfuture) that were initiated with that server.

4.8 Cross Protocol Attack

An attack that enables an adversary to successfully impersonate a server toa random client after obtaining sufficient signed elliptic curve keys from theoriginal server.

4.9 Renegotiation

The attacker forms a TLS connection with the target server, injects contentof his choice, and then splices in a new TLS connection from a client.

4.10 Triple Handshake

The triple handshake attack enables the attacker to cause two TLS connec-tions to share keying material.

4.11 Virtual Host Confusion

SSLv3 fallback and improper handling of session caches on the server sidecan be abused by an attacker to establish a malicious connection to a virtualhost other than the one originally intended and approved by the server.

4.12 Denial of Service

A transport layer DoS attack involves sending many connection requests to

a target host. Since a client can easily force the server to expend relativelylarge computational work, the risk of malicious clients and botnets mountingdenial-of-service attacks is very real. Example of DoS in transport layer isTCP SYN flood, where succession of SYN requests to server crashes thesystem

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4.13 Implementation Issues

Even when the protocol is properly specified, this does not guarantee thesecurity of implementations. In fact, there are very common issues that oftenplague TLS implementations. Some widespread implementation issues are:

4.13.1 Heartbleed

This weakness allows stealing the information protected, under normal con-ditions, by the SSL/TLS encryption used to secure the Internet. The vul-nerability arises from buffer over-read, a situation where more data can beread than should be allowed.

4.13.2 Early CCS

Some version of OpenSSL accepts ChangeCipherSpec (CCS) inappropriatelyduring a handshake. A successful exploit allows an attacker to intercept, de-crypt, and modify the underlying plaintext traffic between vulnerable clientsand servers.

4.13.3 OprahSSL

An attacker could cause certain checks on untrusted certificates to be by-passed, such as the CA flag, enabling them to use valid leaf certificate to

act as a CA and “issue” an invalid certificate.

5 Transport Layer Protection Benefits

The primary benefit of transport layer security is the protection of webapplication data from unauthorized disclosure and modification when it istransmitted between clientsand server. Transport layer security also pro-vides integrity guarantees and replay prevention.

6 References

1. ”Insufficient Transport Layer Protection.” Veracode.

2. ”RFC 7457 - Summarizing Known Attacks on Transport Layer Secu-rity (TLS) and Datagram TLS (DTLS).” Internet Engineering TaskForce (IETF)

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Security Issues in Transport Layer