RefuseServiceDenial-of-Service Attacks

  • Prevents systems from processing or responding to legitimate traffic
  • Transmits data packets
  • Exploits a known fault in an OS, service or application
  • Results in system crash or CPU at 100%
  • Distributed reflective denial of service DRDoS
  • Reflected approach, rather than direct to victim, manipulates traffic so that attack is reflected back to victim from other sources
  • Example: DNS Poisoning and SMURF

If you are among the 10 thousand people who have not yet sent a 100% on our free security assessment, here's a cheat sheet for the most common and well-known exploits affecting SSL today. 

Security Concepts Quiz One  (Come on, you can do it!). 

Can You Math The Exploit?

Smurf and Fraggle Attacks

  • A smurf attack is another type of flood attack, but it floods the victim with Internet Control Message Protocol (ICMP) echo packets instead of with TCP SYN packets.
  • More specifically, it is a spoofed broadcast ping request using the IP address of the victim as the source IP address. Ping uses ICMP to check connectivity with remote systems.
  • Normally, ping sends an echo request to a single system, and the system responds with an echo reply. However, in a smurf attack, the attacker sends the echo request out as a broadcast to all systems on the network and spoofs the source IP address. All these systems respond with echo replies to the spoofed IP address, flooding the victim with traffic.

Smurf attacks take advantage of an amplifying network (also called a smurf amplifier) by sending a directed broadcast through a router.

  • All systems on the amplifying network then attack the victim.
  • However, RFC 2644, released in 1999, changed the standard default for routers so that they do not forward directed broadcast traffic.
  • When administrators correctly configure routers in compliance with RFC 2644, a network cannot be an amplifying network.
  • This limits smurf attacks to a single network. Additionally, it’s becoming common to disable ICMP on firewalls, routers, and even many servers to prevent any type of attacks using ICMP.
  • When standard security practices are used, smurf attacks are rarely a problem today.


  • Fraggle attacks are similar to smurf attacks.
  • However, instead of using ICMP, a fraggle attack uses UDP packets over UDP ports 7 and 19.
  • The fraggle attack will broadcast a UDP packet using the spoofed IP address of the victim.
  • All systems on the network will then send traffic to the victim, just as with a smurf attack.


  • Robots or Zombies, introduced through malware, often browser based
  • Allows a herder to send instructions to the computer
    • Gamover Zues GOZ,
    • CrytoLocker ransomware
    • Simda
    • Esthost DNS Changer

Ping of Death – Teardrop and Land Attacks 

  • POD
    • Oversized packets, changes size of packets to over 64KB
    • Results crash, buffer overflow
    • Rarely successful today
  • Teardrop
    • Fragments traffic so data can’t be put back together
    • Land Attacks
    • Sends spoofed SYN packets as both source and destination

 These and many additional concepts are core to Networking, Cloud and Cyber Security. 

 They are foundational to any of the following top security threat discussions.

Top 20 cyber risks

SSLv3 is broken

What is SSLv3?  How did it breaK?

Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), both of which are frequently referred to as 'SSL', are cryptographic protocols designed to provide communications security over a computer network.

  • security protocol (cryptographic protocol or encryption protocol)
  • performs a security-related function and applies cryptographic methods, often as sequences of cryptographic primitives. A protocol describes how the algorithms should be used. A sufficiently detailed protocol includes details about data structures and representations, at which point it can be used to implement multiple, interoperable versions of a program.[1]

Cryptographic protocols are widely used for secure application-level data transport. A cryptographic protocol usually incorporates at least some of these aspects:

For example, Transport Layer Security (TLS) is a cryptographic protocol that is used to secure the web (HTTP/HTTPS) connections. It has an entity authentication mechanism, based on the X.509 system; a key setup phase, where a symmetric encryption key is formed by employing public-key cryptography; and an application-level data transport function. These three aspects have important interconnections. Standard TLS does not have non-repudiation support.

  • There are other types of cryptographic protocols as well, and even the term itself has various readings; Cryptographic application protocols often use one or more underlying key agreement methods, which are also sometimes themselves referred to as "cryptographic protocols". For instance, TLS employs what is known as the Diffie-Hellman key exchange, which although it is only a part of TLS per se, Diffie-Hellman may be seen as a complete cryptographic protocol in itself for other applications.

Whitfield Diffie and women who will talk to him 

(This is Whitfield Diffie and the "women who will talk to him".  Please excuse the Nerds Who Attract joke.  Only I, and 20 thousand other RSA attendees will get it.)

So, what are some of the more well-known exploits that resulted from a lack of security awareness, failed patching, and other generally poor choices in the design of our hastily migrated to cloud applications?


Alert (TA14-290A)

SSL 3.0 Protocol Vulnerability and POODLE Attack

Original release date: October 17, 2014 | Last revised: September 30, 2016

Some Transport Layer Security (TLS) implementations are also vulnerable to the POODLE attack.Overview

US-CERT is aware of a design vulnerability found in the way SSL 3.0 handles block cipher mode padding. The POODLE attack demonstrates how an attacker can exploit this vulnerability to decrypt and extract information from inside an encrypted transaction.


The SSL 3.0 vulnerability stems from the way blocks of data are encrypted under a specific type of encryption algorithm within the SSL protocol. The POODLE attack takes advantage of the protocol version negotiation feature built into SSL/TLS to force the use of SSL 3.0 and then leverages this new vulnerability to decrypt select content within the SSL session. The decryption is done byte by byte and will generate a large number of connections between the client and server.

While SSL 3.0 is an old encryption standard and has generally been replaced by TLS, most SSL/TLS implementations remain backwards compatible with SSL 3.0 to interoperate with legacy systems in the interest of a smooth user experience. Even if a client and server both support a version of TLS the SSL/TLS protocol suite allows for protocol version negotiation (being referred to as the “downgrade dance” in other reporting). The POODLE attack leverages the fact that when a secure connection attempt fails, servers will fall back to older protocols such as SSL 3.0. An attacker who can trigger a connection failure can then force the use of SSL 3.0 and attempt the new attack. [1]

Two other conditions must be met to successfully execute the POODLE attack: 1) the attacker must be able to control portions of the client side of the SSL connection (varying the length of the input) and 2) the attacker must have visibility of the resulting ciphertext. The most common way to achieve these conditions would be to act as Man-in-the-Middle (MITM), requiring a whole separate form of attack to establish that level of access.

These conditions make successful exploitation somewhat difficult. Environments that are already at above-average risk for MITM attacks (such as public WiFi) remove some of those challenges.

On December 8, 2014, it was publicly reported [2,3,4] that some TLS implementations are also vulnerable to the POODLE attack.Impact

The POODLE attack can be used against any system or application that supports SSL 3.0 with CBC mode ciphers. This affects most current browsers and websites, but also includes any software that either references a vulnerable SSL/TLS library (e.g. OpenSSL) or implements the SSL/TLS protocol suite itself. By exploiting this vulnerability in a likely web-based scenario, an attacker can gain access to sensitive data passed within the encrypted web session, such as passwords, cookies and other authentication tokens that can then be used to gain more complete access to a website (impersonating that user, accessing database content, etc.).


There is currently no fix for the vulnerability SSL 3.0 itself, as the issue is fundamental to the protocol; however, disabling SSL 3.0 support in system/application configurations is the most viable solution currently available.

Some of the same researchers that discovered the vulnerability also developed a fix for one of the prerequisite conditions; TLS_FALLBACK_SCSV is a protocol extension that prevents MITM attackers from being able to force a protocol downgrade. OpenSSL has added support for TLS_FALLBACK_SCSV to their latest versions and recommend the following upgrades: [5]

  • OpenSSL 1.0.1 users should upgrade to 1.0.1j.
  • OpenSSL 1.0.0 users should upgrade to 1.0.0o.
  • OpenSSL 0.9.8 users should upgrade to 0.9.8zc.

Both clients and servers need to support TLS_FALLBACK_SCSV to prevent downgrade attacks.

Other SSL 3.0 implementations are most likely also affected by POODLE. Contact your vendor for details. Additional vendor information may be available in the National Vulnerability Database (NVD) entry for CVE-2014-3566 [6] or in CERT Vulnerability Note VU#577193.[7]

Vulnerable TLS implementations need to be updated. CVE ID assignments and vendor information are also available in the NVD.[8]


  • December 10, 2014 Noted newer POODLE variant (CVE-2014-8730)