Putty Trick – 1. Save output to a file

To automatically save the output to a file while using Putty, you can change one setting of Putty to achieve this.
1. Start putty.exe.
2. Go to Session -> Logging.
3. Select “Printable output”
4. Choose the folder, where you want the file to be placed.
5. Append a file name like &H_&Y&M&D_&T.log to the path (host_YearMonthDay_time.log)
6. Save the profile as default settings.


CCNA Security 210-260 (Santos & Stuppi): Ch01 Questions

I have been away from study as well as blogging for sometime due to my on-going health issues. This year alone, I’ve had three operations and have been off the tangent on my study. Actually, two but the last one was a spin-off of the second. The first was in May, embarrassing to say this but the operation was for hemorrhoidectomy and colonoscopy, it brought me down for about 3 weeks. Then 3 weeks ago, I’ve had a Tonsillectomy, I was so glad that I was finally saying good bye to my beloved 40 year old tonsillitis. Post operation, I was almost over the hill, then on the 14th day, a scab came off the operated part and started bleeding crazy. Last Sunday, I went into Emergency and after almost bleeding to death for 8 hours, the ENT specicialist decided to operate on me again under full anesthetics. I was out for another week and looking forward to going back to work tomorrow. Sadly, I felt the pain up the bumb as well as in the mouth this year. Hopefully, I can keep my promise to completed the CCNA Security 210-260 before the year end. ;).

For anyone who is also struggling with their study, keep your forcus and keep going until you see the end of the tunnel. Yes, there are many tunnels to crosss in our industry, if you stop, you might get run over by the traffic behind you, so keep moving. 🙂

To help the exam prep and also make some go to points, I will simply refer the questions from the books. Yes, I did purchased a hard copy to study for this exam, the videos are also also available from safaribooks.com (Santos & Stuppi videos). Older Barker version is available off torrent sites as form of cbtnugget videos. Love watching Keith Barker’s cbtnuggets, he is a true  legend!

1. Which security term refers to a person, property, or data of value to a company?
a. Risk
b. Asset
c. Threat prevention
d. Mitigation technique

2. Which asset characteristic refers to risk that results from a threat and lack of a countermeasure?
a. High availability
b. Liability
c. Threat prevention
d. Vulnerability

3. Which three items are the primary network security objectives for a company?
a. Revenue generation
b. Confidentiality
c. Integrity
d. Availability

4. Which data classification label is usually not found in a government organisation?
a. Unclassified
b. Classified but not important
c. Sensitive but unclassified
d. For official use only e. Secret
5. Which of the following represents a physical control?
a. Change control policy
b. Background checks
c. Electronic lock
d. Access lists

6. What is the primary motivation for most attacks against networks today?
a. Political
b. Financial
c. Theological
d. Curiosity

7. Which type of an attack involves lying about the source address of a frame or packet?
a. Man-in-the-middle attack
b. Denial-of-service attack
c. Reconnaissance attack
d. Spoofing attack

8. Which two approaches to security provide the most secure results on day one?
a. Role based
b. Defense in depth
c. Authentication
d. Least privilege

9. Which of the following might you find in a network that is based on a defense-in-depth security implementation? (Choose all that apply.)
a. Firewall
b. IPS
c. Access lists
d. Current patches on servers

10. In relation to production networks, which of the following are viable options when dealing with risk? (Choose all that apply.)
a. Ignore it
b. Transfer it
c. Mitigate it
d. Remove it

Interview question: Cisco Voice Engineer: CUCM Database replication value, do you know what you are talking about?

This is a helpful reminder note for all who manages CUCM on day-to-day basis and one of the favorite Voice/IPTel Engineer interview questions. I think I was asked this question in almost every voice Engineer role interviews. Good luck with your next interview!

Q1. What does CUCM database replication value mean to you (CM Administrator)? 

2 = Good, excellent, no behind pain

Other than 2 = Behind pain begins

Value Meaning Description
0 Initialization State This state indicates that replication is in the process of trying to  setup. Being in this state for a period longer than an hour could  indicate a failure in setup.
1 Number of Replicates not correct This state is rarely seen in 6.x and 7.x but in 5.x can indicate its  still in the setup process. Being in this state for a period longer than  an hour could indicate a failure in setup.
2 Replication is good Logical connections have been established and tables match the other servers on the cluster.
3 Tables are suspect Logical connections have been established but we are unsure if tables match.
In 6.x and 7.x all servers could show state 3 if one server is down in  the cluster.
This can happen because the other servers are unsure if  there is an update to a user facing feature that has not been passed  from that sub to the other device in the cluster.
4 Setup Failed / Dropped The server no longer has an active logical connection to receive  database table across. No replication is occurring in this state.

Source: CCO

Q2. How to check?

Option 1: On CUCM OS CLI, run show command

admin:show perf query class “Number of Replicates Created and State of Replication”
==>query class :

– Perf class (Number of Replicates Created and State of Replication) has instances and values:
ReplicateCount -> Number of Replicates Created = 427
ReplicateCount -> Replicate_State = 2 <<< Life is Good

Option 2: On CUCM Unified Reporting 

Cisco Unified Reporting > System Reports > Unified CM Database Status >> Run report



Option 3: Real Time Monitoring Tool (RTMT)

Install RTMT plugin on your desktop. Launch RTMT and then go to “Call Manager > Service > Database Summary”

Q3. How to repair a broken db replication issue?

I have come acorss a very good blog and it shows you on how to repair a broken db replication. Click here.




CCNA Security 210-260: Module 2: Virtual Private Networks (VPNs), Lesson 4: Fundamentals of IP Security

Source: https://www.safaribooksonline.com/library/view/ccna-security-210-260

Lesson 4: Fundamentals of IP Security
4.1 IPsec Concepts, Components, and Operations
4.2 IKE version 1 Fundamentals
4.3 IKE version 2 Fundamentals


4.1 IPsec Concepts, Components, and Operations

The Internet Key Exchange (IKE) Protocol
– IPsec uses IKE protocol to negotiate and establish secured site-to-site or remote access virtual private network (VPN) tunnels.

– IKE is a framework provided by the Internet Security Association and Key Management Protocol (ISAKMP) and parts of two other key management protocols, namely Oakley and Secure Key Exchange Mechanism (SKEME).

– In IKE Phase 1: IPsec peers negotiate and authenticate each other. In Phase 2, they negotiate keying materials and algorithms for the encryption of the data being transferred over the IPsec tunnel.
Two versions of IKEs.
IKE v1: Defined in RFC 2409
IKE v2: Defined in RFC 4306

IKE Protocol Details:
– IKE v2 enhances the function of performing dynamic key exchange and peer authentication.
– IKE v2 simplifies the key exchange flows and introduces measures to fix vulnerabilities present in IKEv1.
– Both IKEv1 and IKEv2 protocols operate in two phases.
– IKEv2 provides a simpler and more efficient exchange.


4.2 IKE version 1 Fundamentals

IKEv1: Who begins the negotiation?
– The initiator sends over all of its IKE Phase 1 policies, and the other VPN peer looks at all of those policies to see whether any of its own policies match the ones it just received.
– If there is a matching policy, the recipient of the negotiations sends back information about which received policy matches, and they use that matching policy for the IKE Phase 1 tunnel.

IKEv1 Phase 1
A handy way to recall the five pieces involved in the negotiation of the IKE Phase 1 tunnel, you might want to remember that the two devices HAGLE over IKE Phase 1:

H: Hash
A: Authentication Method
G: DH group (a stretch, but it works)
L: Lifetime of the IKE Phase 1 tunnel
E: Encryption algorithm to use for the IKE Phase 1 tunnel
The DH (Diffie-Hellman) Exchange
– Now having agreed to the IKEv1 Phase 1 policy of the peer, the two devices run the DH key exchange.
– They use the DH group (DH key size for the exchange) they agreed to during the negotiations, and at the end of this key exchange they both have symmetrical keying material (which is a fancy way of saying they both have the same secret keys that they can use with symmetrical algorithms).
– DH allows two devices that do not yet have a secure connection to establish shared secret keying material (keys that can be used with symmetrical algorithms, such as AES).
Authenticating the peer (last step in IKEv1 phase 1)
– The last step of IKE Phase 1 is to validate or authenticate the peer on the other side.
– For Authentication, they use whatever they agreed to in the initial proposal/policy, and if they successfully authenticate with each other, we now have an IKE Phase 1 tunnel in place between the two VPN gateways.
– The authentication could be done either using a PSK or using RSA digital signatures.


Phase 1:
– The next step is to complete the IKEv1 Phase 2 negotiation.
– The entire conversation and negotiation of the IKEv1 Phase 2 tunnel are completely done in private because of the IKEv1 Phase 1 tunnel protection the negotiated traffic.
– The IKE Phase 2 tunnel includes the hashing and encryption algorithms.
– The name of the mode for building the IKE Phase 2 tunnel is called “Quick Mode“.
4.3 IKE version 2 Fundamentals

What’s different in IKEv2?

* IKEv2 does not consume as much bandwidth as IKEv1.
* IKEv2 supports EAP authentication while IKEv1 doesn’t.
* IKEv2 supports the Mobility and Multi-homing (MOBIKE) protocol while IKEv1 doesn’t.
* IKEv2 has built-in NAT traversal while IKEv1 doesn’t.

** UDP port 4500 is used.
*** Protocol 50 (ESP) or 51 (AH)
*** NAT Transversal need to be used on UDP port 4500

IKEv2 Phase 2
* Phase 2 in IKEv2 is CHILD_SA (Child Security Association)
* The first CHILD_SA is the IKE_AUTH message pair.
* This phase is comparable to IKEv1 Phase 2.
* Additional CHILD_SA message pairs can be sent for rekey and informational messages.
* The CHILD_SA attributes are defined in the Data Policy.



CCNA Security 210-260: Module 2: Virtual Private Networks (VPNs), Lesson 3: Fundamentals of VPN Technology and Cryptography

Lesson 3: Fundamentals of VPN Technology and Cryptography
3.1 Understanding VPNs and Why We Use Them
3.2 Cryptography Basic Components
3.3 Public Key Infrastructure
3.4 Putting the Pieces of PKI to Work

3.1 Understanding VPNs and Why We Use Them

What is a Virtual Private Network (VPN)?
“A virtual private network that allows connectivity between two or more devices.”

Those two devices could be computers on the same local-area network or could be connected over a wide-area network.

Two major types of VPNS:
1. Remote access: uses SSL or IPSec VPN tunnel, terminates tunnel at either IOS/ASA and then can access corporate network from anywhere on the internet, as if it is directly connected to the network.
2. Site-to-Site : This is between two routers across WAN, terminate IPSec tunnel so the site A devices can access resources at site B and visa versa.

Examples of VPN Technologies
2. SSL

The main benefits of using either remote-access or site-to-site VPNs include the following:
Confidentiality: – Only the intended parties can understand the data that is sent.
– Any party that eavesdrops may see the actual packets, but the contents of the packet or the payload are encrypted (also called cipher text)
Data integrity: – Ensuring that the data is accurate from end to end
Authentication: – Peer authentication done in many ways. E.G.) Pre-shared keys, public and private key pairs, certificates, and user authentication in remote-access VPNs
Antireplay protection: – This just means that once a VPN packet has been sent and accounted for, that exact same VPN packet is not valid the second time in the VPN session.
3.2 Cryptography Basic Components

A Cipher is a set of rules, which can also be called an algorithm, about how to perform encryption or decryption.
Common methods that ciphers use
Substitution: substitutes one character for another. For example, substituting each letter from the alphabet with the previous letter of the alphabet.

Polyalphabetic: similar to substitution, but instead of using a single alphabet, it could use multiple alphabets and switch between them by some trigger character in the encoded message.

Transposition: uses many different options, including the rearrangement of letters.



– A one-time pad (OTP) is a good example of a key that is only used once.
– Using this method, to encrypt a 32-bit message, a 32-bit key is also used. This is also called the pad, which is used one time only.
– Each bit from the pad is mathematically computed with a corresponding bit from our message, and the results are our cipher text, or encrypted content.
– The pad must also be known by the receiver if he wants to decrypt the message.

Note: Another use of the acronym OTP is for a user’s one-time password, which is a different topic than the OTP (one-time pad).
A block cipher is a symmetric key cipher (same key to encrypt and decrypt) that operates on a group of bits called a block.

– Advanced Encryption Standard (AES)
– Digital Encryption Standard (DES)
– Triple Digital Encryption Standard (3DES)
– Blowfish
– International Data Encryption Algorithm (IDEA)

A stream cipher is a symmetric key cipher (same key to encrypt as decrypt), where each bit of plain-text data to be encrypted is done 1 bit at a time against the bits of the key stream, also called a cipher digit stream.
Symmetric vs Asymetirc Encryption Algorithm:

Symmetric Encryption Algorithms
– a.k.a a symmetric cipher, uses the same key to encrypt the data and decrypt the data.
– Two devices connected via a VPN, both need the key or keys to successfully encrypt and decrypt the data that is protected using a symmetric encryption algorithm.

– 3DES
– RC2, RC4, RC5, RC6
– Blowfish

Symmetrical encryption algorithmmms are used for most of the data that we protect in VPNs today.
Asymmetirc Encryption Algorithms
An example of an asymmetric algorithm is public key algorithms. Instead of using the same key for encrypting and decrypting, we use two different keys that mathematically work together as a pair. These are called the public and private keys. Together they make a key pair.

– RSA – named after “Rivest, Shamir and Adleman” (investors)
– Diffie-Hellman (DH)
– ElGamal – based on the DH exchange
– Digital Signature Algorithm (DSA) – created by the NSA
– Elliptic Curve Cryptography (ECC)
Hashing is a method used to verify data integrity.

4 most popular types of hashes:
1. Message digest 5 (MD5): This creates a 128-bit digest.
2. Secure Hash Algorithm 1 (SHA-1): This creates a 160-bit digest.
3. Secure Hash Algorithm 2 (SHA-2): Options include a digest between 224 bits and 512 bits.
4. Secure Hash Algorithm 3 (SHA-3): Options include a digest between 224 bits and 512 bits.

Hashed Message Authentication Code (HMAC)
– Instead of using a hash that anyone can calculate, it includes in its calculation a secret key of some type.
– Then only the other party who also knows the secret key can calculate the resulting hash that can correctly verify the hash.
– An attacker who is eavesdropping and intercepting packets cannot inject or remove data because he does not have the key or keys used for the calculation.
When you sign something, it often represents a commitment to follow through, or at least prove that you are who you say you are. In cryptography a digital signature provides three core benefits:

1. Authentication
2. Data Integrity
3. Nonrepudiation
Key management deals with:
– Generating keys
– Verifying keys
– Exchanging keys
– Storing keys
– at the end of their lifetime, destroying keys
3.3 Public Key Infrastructure

PKI and Public and Private Keys
A key pair is a set of two keys (a private and a public key) that work in combination with each other as a team.
The public key may be shared with everyone, but the private key is not shared with anyone.
Certificate Authorities
A certificate authority (CA) is a system that creates an issues digital certificates.

Inside of a digital certificate is information about the identity of a device, such as:
– its IP Address
– Fully Qualified Domain Name (FQDN)
– The public key of that device

Root and Identity Certificates
A digital certificate can be thought of as an electronic document that identifies a device or person.
– A root certificate contains the public key of the CA server and the other details about the CA server.
– An identity certificate is similar to a root certificate, but it describes the client and contains the public key of an individual host (the client).


3.4 Putting the Pieces of PKI to Work

1. Authenticate CA Server by downloading “Root Cert” from the CA server to Client
2. Client can request its own identity certificate, CA server generating the public and private key pair. ID certificate can be for a device or a person, the client can be a PC/firewall/router.

Simple Certificate Enrollment Protocol (SCEP) is used to generate the ID certificate. SCEP is most popular certification method.

Certificate Revocation:
Certificate revocation List (CRL): list of certificate which should be no longer trusted.
Online Certificate Status Protocol (OSCP): Newer certification revocation method. Revoked – irreversible or Hold status – temporary.



CCNA Security 210-260: Module 1: Fundamentals of Network Security, Lesson 2: Common Security Threats

Source: Safaribooksonline training, https://www.safaribooksonline.com/library/view/ccna-security-210-260

Lesson 2: Common Security Threats
2.1 Network Security Threat Landscape
2.2 Distributed Denial of Service (DDoS) Attacks
2.3 Social Engineering Methods
2.4 Man-in-the-middle Attacks
2.5 Malware Identification Tools
2.6 Data Loss and Exfiltration Methods


Explores different types of threats discussed in CCNA Security.

2.1 Network Security Threat Landscape

Facts learnt in Lesson 1:
“Over 75% of attackers start extracting data within minutes”
“Over 50% of attacks are left undetected for months, if at all”

Current threat landscape
– Custom malware is being created and deployed at the victim’s side
– Multiple bad actors are present simultaneously
– Attacked infrastructure is a platform for the next attack
– Many are blind to network malfeasance
– Some are conceding loss of control
– denial of Service can be a precursor to damage
– Undetected communication to embargoed countries

Motivations behind threat actors
– Financial
– Disruption – several reasons:
– To protest the actions, decisions, or behaviors of a given organization
– To serve as a distraction while the malicious actors plant something within the network to be leveraged at a future point in time
– To gain media attention

– Geopolitical – nation states (Referred to as “The cyber war”)

2.2 Distributed Denial of Service (DDoS) Attacks

DDoS is when the attack source is more than one and often thousands of IP Addresses and hosts.
E.G.) Attack on a web site: The main intent of DDoS attack is to consume all the network resources to deny services to legitimate users to the site.

3 General Categories of DDoS attacks

Direct   Reflected   Amplification
The source of the attack generates the packets, regardless of protocol, application that are sent directly to the victim.
As explained in above example.
The sources of the attack are sent spoofed packets that appear to be from the victim, and then the sources become unwitting participants by sending the response traffic back to the intended victim.

UDP is often used as the transport mechanism because it is more easily spoofed due to the lack of a three-way handshake.

Example: NTP

A form of reflected attacks in which the response traffic (sent by the unwitting participants) is made up of packets that are much larger than those that were initially sent by the attacker (spoofing the victim).

Example: DNS Amplication Attacks

2.3 Social Engineering Methods

What is Social Engineering?
– Bad actors use social engineering by relying on the human element to steal information and/or create holes in the victim’s organization
– Social engineering is evolving so rapidly that technology solutions, security policies, and operational procedures alone cannot protect critical resources.
Not a technical attack but attacking human weakness.

Social Engineering Tactics
Phishing: elicits secure information through an e-mail message that appears to come from a legitimate source such as a service provider or financial institution. The e-mail message may ask the user to reply with the sensitive data, or to access a website to update information such as a bank account number.
Malvertising: malicious ads on trusted websites, which results in users’ browsers being inadvertently redirected to sites hosting malware.
Phone scams: not uncommon for someone to call up an employee and attempt to convince employees to divulge information about themselves or others withing the organization. An example is a miscreant posing as a recruiter asking for names, e-mail addresses, and so on for members of the organization and then using that information to start building a database to leverage for a future attack, reconnaissance mission, and so forth. Another example is a job interview.

Defenses against Social Engineering
Security policies and procedures take the guesswork out of operations and help employees make the right security decisions.

* Education A huge part depending against Social Engineering. SE is not a technical attack, it targets human behaviors.
* Password Management Use complex password and password guidelines.
* Two-factor Authentication
* Antivirus/Antiphishing Defenses
* Change management
* Information Classification Refer to Lesson 1 discussion.
* Physical Security
2.4 Man-in-the-middle Attacks

A man-in-the-middle attack results when attackers place themselves in line between two devices or people that are communicating, with the intent to perform reconnaissance or to manipulate the data as it moves between them.

2.5 Malware Identification Tools

Packet Captures – collect, store and analyse traversing the network
Netflow – does not provide the same level of information as packet capture but is a great tool for malware identification tools, extracting information to traceback the packet.
Cisco Advanced Malware Protection (AMP) – provides visibility and control to protect against highly sophisticated attacks such as zero day, persistent advanced malware threats in the network.
Cisco Firepower Next-generation Intrusion Prevention System (NGIPS) – provides multi-layer advanced protection that can help identify and mitigate malware attacks in the network.


2.6 Data Loss and Exfiltration Methods

Data Loss and Exfiltration

There are several types of data that are particularly attractive to the miscreants:
– Intellectual Property (IP)
– Personally Identifiable Information (PII)
– Credit/debit cards

Examples of Data Loss and Exfiltration techniques:
– HTTP(s) tunneling
– DNS tunneling



CCNA Security 210-260: Module 1: Fundamentals of Network Security, Lession 1: Networking Security Concepts and Common Principles

Source: CCNA Security 210-260, https://www.safaribooksonline.com/library/view/ccna-security-210-260/

Lesson 1: Networking Security Concepts and Common Principles
1.1 Understanding Network and Information Security Basics
1.2 Confidentiality, Integrity, and Availability
1.3 Classifying Assets
1.4 Types of Security Vulnerabilities
1.5 Classifying Countermeasures
1.6 Attack Methods & Vectors
1.7 Applying Fundamental Security Principles To Network Design
1.8 Understanding the Security Attack Surface in Different Network Typologies


1.1 Understanding Network and Information Security Basics
– Attacks are more targeted and sophisticated
– Custom malware created even at the victim’s site
– More organized attack campaigns

Every organization, individual or system is a target. Doesn’t matter the size/country/who.
You are a target, attackers are always target to steal:
– Intellectual Property
– Personal Information
– Distributed Development (source code)

Recent evolution of threats:
– Custom malware is being deployed
– Multiple bad actors are present simultaneously
– Attached infrastructure is a platform for the next attack
– Many are blind to network malfeasance
– Some are conceding loss of control
– Denial of Service can be a precursor to damage
– Undetected communication to embargoed countries

Today’s reality:
– Over 75% of attacks start extracting data within minutes.
– Over 50% of attacks are left undetected for months, if at all
– Detection and response capabilities must change
Security professionals must understand what they are trying to protect… and from WHOM?
We need to think like actors and bad guys, try to understand all the threats happening now days.

The Industrialization of hacking: Cyber crime as a business. Often the criminals know about your network that you know.
Threats grow more sophisticated every day.
1990 – 2000 Viruses
1997 – Phishing, low sophistication,
2000 – 2005 Worms
2005 – Hacking becomes an Industry
2005 – today: Spyware and rootkits
2015 – APTs cyber ware
2016 – Sophisticated attacks, attack as service
2020 – ???

“Criminals know more about your network than you do”
Initial malware may remain dormant for months to learn vulnerabilities and network custom malware developed to attack after learning your vulnerabilities.

Typical stages of a data breach:


What is a vulnerability?
A vulnerability is an exploitable weakness in a system or its design. Vulnerabilities can be found in protocols, operating systems, applications, and system designs.

What is a threat?
A threat is any potential danger to an asset. If a vulnerability exists but has not yet been exploited or, more importantly, it has not yet publicly known, the threat is not yet realized.
If someone is actively launching an attack against your system and successfully accesses something or compromises your security against an asset, the threat is realized.

What is a countermeasure?
A countermeasure is a safeguard that somehow mitigates a potential risk. It does so by either reducing or eliminating the vulnerability, or at least reduces the likelihood of the threat agent to actually exploit the risk.


1.2 Confidentiality, Integrity, and Availability

CIA concept:


Confidentiality means that only the authorized individuals/systems can view sensitive or classified information. This also implies that unauthorized individuals should not have any type of access to the data.

Integrity applies to systems and data. For data means that changes made to data are done only by authorized individuals/systems. Corruption of data is a failure to maintain data integrity.

Availability also applies to systems and to data. If the network or its data is not available to authorized users the impact may be significant to organizations and users who rely on that network as a business tool. The failure of a system, to include data, applications, devices, and networks, generally equates to loss of revenue.


1.3 Classifying Assets

What is an Asset?

An asset is an item that is to be protected and can include property, people and information/data that have value to the company.

This includes intangible items such as proprietary information or trade secrets and the reputation of the company.

The data could include company records, client information, proprietary software, and so on.

Asset classifications:

Type of classification Calssification
Governmental classifications * Unclassified
* Sensitive but unclassified (SBU)
* Confidential
* Secret
* Top secret
Private sector classifications * Public
* Sensitive
* Private
* Confidential
Classification criteria * Value
* Age
* Replacement cost
*Useful lifetime
Classification roles * Owner (the Group ultimately responsible for the data, usually senior management of a company)

* Custodian (the group responsible for implementing the policy as dictated by the owner)

* User (those who access the data and abide by the rules of acceptable use for the data)

1.4 Types of Security Vulnerabilities

Understanding the weaknesses and vulnerabilities in a system or network is a huge step toward correcting the vulnerability or putting in appropriate countermeasures to mitigate threats against those vulnerabilities.

Different types of security vulnerabilities

  • Policy flaws
  • Design errors
  • Protocol weaknesses
  • Misconfiguration
  • Software vulnerabilities
  • Human factors (weakest link, social engineering)
  • Malicious software
  • Hardware vulnerabilities
  • Physical access to network resources


Buffer overflows

  • Buffer
    • Data Container
  • Buffer overflow:
    • Stuffing too much data into a data container
    • Data written beyond the container overwrites other data and/or control information


Instruction Pointer (EIP)

  • Holds address of next instruction to execute
  • Is impacted by jumps, branches and returns
  • Is only valid if pointing to an executable memory region


What is the stack?

  • Holds all local variables and parameters used by any function
  • Remembers the order in which functions are called so the function returns correctly
  • When a function is called, local variables and parameters are “pushed” onto the stack
  • When the function returns, these locals and parameters are “popped” off of the stack


What does main’s frame look like on the stack?

What happens when we put more than 512 bytes in mybuffer[]?

What does main’s frame look like on the stack? We overwrite saved EBP, EIP, and more.


Target: EIP

Goal: Control execution flow

  • locate saved EIP
  • place a favorable address in the saved EIP
  • Don’t crash


Cross Site Scripting (XSS)

  • XSS is the ability to execute Javascript code within the Browser’s Document Object Model (DOM)
    • In non-web-tech-speak: Run scripts in the user’s context
    • The web application does not “taint” the data before it is stored and/or reflected back to the end user
  • Stored SSX:
    • Web application stores the attack in the database for later display
    • Common to attack multiple users on forums, etc
  • Reflected XSS:
    • Immediately attack the user based on input
    • Typically performed with social engineering when an XSS vulnerability is discovered on a trusted website

What is the threat from XSS?

  • Cookie stealing
  • Browser control
  • Forced actions (CSRF)
  • Enhanced social engineering


XSS “Cousin”: CSRF

  • Cross site request forgery
  • Exploits the trust a site has in a users browser
    • Typically uses social engineering or XSS to lure a user
  • Some mitigation:
    • Don’t allow “blind submissions” — Use a secret token
    • Check the refer header

<img src=”http://bank.example.com/withdraw?account=Alice&amount=1000000&for=Mallory”&gt;


SQL Injection

  • Dynamic web applications require database back ends
  • Developers don’t always sanitize user input before using it in SQL Queries


Additional Vulnerability categories



1.5 Classifying Countermeasures

        Classifying controls & countermeasures


Administrative Controls

  • These consist of written policies, procedures, guidelines and standards
    • Examples:
      • written acceptable use policy (AUP)
      • change control process that needs to be followed when making changes to the network
  • Administrative controls could involve items such as background checks for users


Physical Controls

Physical security for the network servers, equipment, and infrastructure.


  • Door locks, gates, badge access
  • Cameras
  • a redundant system like an uninterruptible power supply


Logical Controls

  • These consist of passwords, firewalls, intrusion prevention systems, access lists, VPN tunnels, and so on.
  • Logical controls are often referred to as technical controls.


1.6 Attack Methods & Vectors

Attack methods

Most attackers do not want to be discovered and so they use a variety of techniques to remain in the shadows when attempting to compromise a network.

Attack methods: Reconnaissance

Used to find information about the network and the victim: Passive or Active

  • Passive: Studying user behaviors, social media etc.
  • Active: scans of the network to find out which IP addresses respond, and further scans to see which ports are open and what vulnerabilities are present.

This is usually the first step taken, to discover what is on the network and to determine potential vulnerabilities.

Attack methods: Social Engineering

  • Targets the weakest link: the user.
  • If the attacker can get the user to reveal information, it is much easier for the attacker than using some other method of reconnaissance.


  • Phishing presents a link that looks like a valid trusted resource to a user. When the user clicks it, the user is prompted to disclose confidential information such as usernames/passwords.
  • Pharming is used to direct a customer’s URL from a valid resource to a malicious one that could be made to appear as the valid site to the user. From there, an attempt is made to extract confidential information from the user.

Attack methods: Privilege Escalation

The process of taking some level of access (whether authorized or not) and achieving an even greater level of access.

Example: an attacker who gains user mode access to a router and then uses a brute-force attack against the router, determining what the enable secret is for privilege level 15 access.

Attack methods: Backdoors

An application can be installed to either allow future access or to collect information to use in further attacks.

Many back doors are installed by users clicking something without realizing the link they click or the file they open is a threat. Back doors can be also be implemented as a result of a virus or a worm (often referred to as malware).

Attack methods: Remote code execution

  • One of the most devastating actions available to an attacker is the ability to execute code within a device.
  • Code execution could result in an adverse impact to the confidentiality (attacker can view information on the device), integrity (attacker can modify the configuration of the device), and availability (attacker can create a denial of service through the modification of code) of a device.

Attack methods: Man-in-the-Middle Attacks

  • A man-in-the-middle attack results when attackers place themselves in line between two devices that are communicating, with the intent to perform reconnaissance or to manipulate the data as it moves between them.
  • This can happen at Layer 2 or Layer 3.
  • The main purpose is eavesdropping, so the attacker can see all the traffic.

Attack methods: Denial-of-service (DoS) and Distributed Denial-of-Service (DDoS) Attacks

  • When numerous or hundreds/thousands of systems send traffic to a victim and this produces a denial of service condition where the genuine users cannot access the site and unable to use the service. Covered in depth in lesson 2.

Attack methods: Botnet & Command & Control (CnC)

  • A botnet is group of private computers that are infected by malware and controlled by attacker, performing malicious activities. Some activities include, sending spams, carry on denial of service attacks from these private computers.
  • Bots are controlled by CnC (Command & Control) server. Historically the CnC control is operated over IRC (Internet Relay Chat), in recent times, CnC control can be done through TLS/SSH/IPSec tunnels. Also, twitter is used for CnC control environment. Infected machines are controlled by the bad actors to carry out specific attacks. Sending spam or steal information from victims.


1.7 Applying Fundamental Security Principles To Network Design

Examples of guidelines for secure network architecture:

  • Rule of least privilege – give a user or a system just enough privilege to carry out certain tasks
  • Defense in depth –  a layer approach on how to apply security within an organization
  • Separation of duties – a concept of having more than one person completing a task to prevent fraud, malicious activities or errors


Improving Security Posture:



1.8 Understanding the Security Attack Surface in Different Network Typologies

  • We need to understand security attack surface in different network typologies and environments, including BYOB (Bring Your Own Device), firewalls, Mobile device Management (MDM), Identity Management Systems (IDS) and other devices within security network environment. Different technologies covered in detail in later chapters.
  • DC environment – it is also important to understand different types of threats in DC’s. Example, The North-South traffic is the traffic carried to and from the data center and other parts of the network. On the other hand, the East-West traffics is referred to as lateral movement within the data center. Whenever there is a security compromise, it is important to know how traffics flow as often the traffic from the compromised machine traverses both from/to North-South and East-West directions.