Fast Flux Domains

by Süleyman Petek 30. Kasım 2015 12:25
According to Wikipedia : "Fast flux is a DNS technique used by botnets to h

According to Wikipedia : "Fast flux is a DNS technique used by botnets to hide phishing and malware delivery sites behind an ever-changing network of compromised hosts acting as proxies." When a domain of a fast flux network is resolved, it returns more than one IP addresses. These domains continuously changes the IP address order that the domains are returned, this technic is called round-robin. The HoneyNet project provides a deep information about this issue : Know Your Enemy (http://www.honeynet.org/papers/ff)

It will be more effective to realize fast flux networks otherwise you will just waste your time blocking each IP address for them. Instead, blocking  the domain would be much more intelligent.

The fast flux domains will return several IP addresses when you resolve them or may return only one address but change it frequently.

How can we catch it ? 

A German security company BFK will help us at first step : http://www.bfk.de/bfk_dnslogger_en.html The BFK query page will allow us to query for passive DNS services.It is obvious that passive DNS search results will return many IP addresses for a fast flux network domain. If your search results contains dozens of different IP addresses, you can say that the domain you searched is a member of a fast flux domain.

We have another way  to check the status, that is checking the TTL value. If the TTL value is very low and the hostname is changing the IP address very quickly, it can be said that a fast flux domain. The value of TTL is zero means DNS server are not caching the IP addresses. You can use "dig" in Linux to find the TTL value of a domain.



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IT Security | Awareness | Malware | Malware Analysis | Web Defense

Secure Software Development Lifecycle

by Süleyman Petek 13. Temmuz 2015 23:00
Security should be a part of your DNA while building  a software system.

Security should be part of your DNA while building a software system. Here below a short list for acronyms.

Information Security Risks: The probability that a particular threat-source will exercise a particular information system vulnerability and the resulting impact if this should occur.

Software Security: A way to defend against software exploits by building software to be secure.

Application Security: A way to defend against software exploits  after deployment is complete.

Return Of Security Investment in Security (ROSI): The total amount of money that an organization is expected to save in a year by implementing a security control.

The core components of Secure SDLC process are:

  • Clear and detailed requirements of business
  • Security requirements 
  • Threat modelling (Early in the security design phase, threat modelling should be done in order to identify the potential threats that exist specific to the application.)
  • Design
  • A policy for secure coding
  • A framework for secure coding (OWASP may be a resource here)
  • Segregation of environments (Dev/Test/Staging/PreProd/Prod)
  • Static and Dynamic Analysis of the code
  • Change management
  • Release management

To mitigate the probability of writing insecure code, a few steps should be included in the SDLC. Since writing secure code is vital for minimizing the occurrence of vulnerabilities, it is worth elaborating on this topic for the benefit of executives. This step in development is too often misunderstood or deemed to be of secondary importance compared with production deadlines. It is worth to review the basic steps of writing secure code and at some point it may look as an attractive return on investment.

Secure coding needs some key factors:

  • Top level management buy-in
  • Security architect engagement
  • Segregation of duties
  • Backups
  • Monitoring and logging of events
  • Patch management
  • Password management (authentication-authorization)
  • Session management
  • Input validation
  • Output encoding
  • Exception management (Fail safely)
  • Developer training (Create awareness, educate)
As you see the cost of a bug during SDLC, the security issues should be considered and fixed as early as possible.



What can you lose if you don't ?
  • Reputation
  • Data
  • Money
  • Time
And never forget that risks are for managers, not for developers !


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IT Security | Awareness | Secure Coding | Web Security | Web Attack | Web Defense

Web Application Security 101

by Süleyman Petek 11. Temmuz 2015 14:25
Since the proliferation of internet nearly for 20 years, the usage of internet in our daily basis ha

Since the proliferation of internet nearly for 20 years, the usage of internet in our daily basis has been increasing day by day. At first we adopted to read newspapers from web, then we started to make our basic financial operations over web from our banks' web sites. The shopping a.k.a "e-commerce" madness followed these. Buying your plane tickets, betting, dating etc. there has been a huge cyber world over there. This is nice until here however you should be aware of your security and privacy in this cyber world. Nowadays mobile applications are very popular, we can not say they will replace web applications but we should notice the power of mobile also. 


Web applications have brought with them a new range of security vulnerabilities. There is a rising awareness that security is an important issue for web applications. Most of web sites say that they are secure because they use SSL. Increasingly, organizations also cite their compliance with Payment Card Industry (PCI) standards to reassure users that they are secure.  In real life, unfortunately the majority of web applications are insecure, despite the widespread usage of SSL technology and the adoption of regular PCI scanning. Here is an example saying that "Half of firms hit by web application security breaches".

There is a non-profit world wide organization called OWASP (Open Web Application Security Project). There are many materials there to learn about application security. Especially OWASP Top 10 may be a very meaningful start for the newbies. It is about the most critical web application security flaws. The latest one was released in 2013.


Web applications face a fundamental problem in order to be secure. The client is outside the application’s control, users can submit arbitrary input to the server side application. The application owners/coders must assume that all input is potentially malicious. The majority of attacks against web applications involve sending crafted input to the server to cause some unexpected event.

Unfortunately SSL can not stop an attacker from submitting crafted input to the server. If the application uses SSL, this simply means that other users on the network cannot view or modify the attacker’s data in transit. 

Some key factors to the problems are

The developers are not aware of the issue, they should be educated for secure coding.

  • The executive management generally care on the dead-lines, not the security of the application. So the developer just try to be as fast as he can do, bypassing the security issues.
  • The resources and the time is limited, the market is too aggressive, executives are somehow right. But security is not an issue  to underestimate. The company can lose money and prestige because of insecure applications.
  • The threats are evolving rapidly.
  • To sum up;

    World Wide Web has evolved from basic static information repositories into highly functional applications that process sensitive data and perform powerful actions with real-world consequences. Most web applications face the core security problem that users can submit arbitrary input. Every aspect of the user’s interaction with the application may be malicious and should be regarded as such unless proven otherwise. All the signs about the current state of web application security shows that although some aspects of security have indeed improved, entirely new threats have evolved to replace them. The overall problem has not been resolved on any significant scale. Attacks against web applications still present a serious threat to both the organizations that deploy them and the users who access them. 


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    IT Security | Awareness | Secure Coding | Web Security | Web Attack | Web Defense

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