Category: Security

Computer Security

How to obtain a digital certificate for free
A digital or SSL certificate consists of two encryption keys, one public and one private, a very common use for digital certificates is to encrypt data exchanges in between a user Internet browser and any e-commerce website but it can also be used to sign documents, encrypt and digitally sign email messages and identify yourself online. Once a digital certificate has been installed in your Internet browser or email client, it is easier to use than encryption software, many users are not even aware they are using it, if the SSL certificate is personalized a password might be asked before using it.

Typical digital certificates will contain a serial number, signature algorithm, issuing authority, valid from and expiry date, public key and a hashed number to guarantee that the key has not been tampered with.

Places to obtain a free digital certificate

CAcert: To be issued an SSL X.509 standard certificate you are asked you to join the CAcert community filling in an online form, in between others you can use CAcert certificates to secure websites, digitally signing or encrypting emails and files.

GetaCert: Not a Certificate Authority (CA), GetaCert appears to be a website using OpenSSL to create a digital certificates online, they can be issued for use with email and websites, all of their certificates are valid for 10 years and wildcards are supported.

StartSSL: Issuing free Class 1 (for individuals) SSL certificates valid for one year, renewable after expiration, security is as good as StartSSL paid for digital certificates but with some limitations like no wildcards allowed and it doesn’t hold identification details.

InstantSSL: Fast and easy to obtain digital certificate from Comodo, it only takes seconds to install and can be used to encrypt and digitally sign your email messages. The private encryption key can be chosen in between high or medium grade depending on needs.

Types of basic digital certificates
- Personal certificate: It works as a digital ID guaranteeing that the person is not someone else, a personal certificate can be used to identify yourself over the Internet with a company or Government agency, digitally sign an email message or a PDF file, a password will normally be asked when carrying out these tasks, using the something you have and something you know security model.
Diagram digital certificate encryption
- Server certificate: It identifies a user when establishing a connection before transmitting any information, email and Usenet servers use a server certificate when authentication takes place via SSL.
- Software certificate: It verifies software before installing it in your computer by checking the code digital signature making sure the program has not been replaced by malware having been signed by a genuine developer, useful when downloading software from the Internet.
Unrecognised digital certificates warnings

All Internet browsers come with digital certificates installed, these are issued by certification authorities like VeriSign or GeoTrust, when the browser comes across a website using a digital certificate which public key is not found in the browser you will get a not recognized certificate warning, this does not mean the site is not safe, it only means one of the key pairs has not been stored in the browser.

It is impossible to have every single company SSL certificate stored in the browser, when you get this kind of warning you should check the digital certificate making sure it is not a man in the middle attack by looking at its properties, when satisfied that everything looks correct, install it, after that you will not get any more security warnings when visiting that site.

Digital certificate security warning

When you install software you could find Windows warning you that the driver has not been digitally signed, Microsoft charges a huge amount for this ‘”privilege” and not all developers can’t afford it, it doesn’t necessarily mean the software is dangerous, it only means it has not been approved by Microsoft.

How to make your own SSL certificate

An alternative to companies issuing free SSL certificates is to create your own Certificate Authority or self-signed digital certificate using OpenSSL, an open source implementation of SSL and TLS, any decent Linux distribution will come with OpenSSL installed, you will need some basic Unix knowledge, go to the command line generate an RSA private key, generate a Certificate Signing Request (CSR) and generate a self-signed certificate, for the necessary commands to do this type man openssl at the Linux command prompt.

You can use OpenSSL and other Unix utilities in Windows using Cygwin, a Unix framework for Windows, it is beyond the scope of this article to explain how Cygwin works.
31 August, 2011
The best emergency antivirus recovery live CDs

If a computer has been infected with a virus and refuses to boot or when it does malware kicks in stopping you from running a virus scanner,using an antivirus live CD will bypass the need to boot the operating system helping you to remove any callous rootkit. There are various Linux based live CDs that allow for data recovery, the antivirus live CDs below have specifically been designed to remove persistent viruses and they are user friendly, meant to be used as a last resort when everything else fails or to save you time if you are a computer administrator.

To use an emergency recovery disk all you have to do is to burn the .iso to blank media, insert the CD rom inside the optical drive, reboot your computer making sure CD-drive is the first booting device in the BIOS and you are in, the live CD will scan your computer for viruses once it boots.

Dr Web live CD: When you boot the CD it detects all disk drives automatically without the need to mount them, you can select a folder or disk to be scanned, the included Midnight Commander file browser allows you to copy any file to an external device and help is available from Dr. Web by email. This live CD lets you check your RAM memory for errors with the Memtest86+ utility making sure that your problem is not a hardware fault.

AVG Rescue CD: It comes with antivirus and antispyware, it defines itself as a portable version of AVG antivirus inside a Linux distribution, you can use it to move files to an external device, test RAM memory, edit registry keys and ping network devices to see if they are reachable, everything is free and it comes with the latest virus signatures database.

AVG antivirus live CD

PCTools live CD: Officially named Alternate Operating System Scanner, this antivirus live CD will detect and remove rootkits and other difficult to delete malware, it uses the Spyware Doctor antivirus engine to scan your files and Windows registry, if it finds something it cleans it up warning you of the location and the virus name.

F-Secure Rescue CD: A customized Knoppix Linux distribution made by F-Secure to remove persistent malware, any virus you have in your operating system will be useless against F-Secure Rescue CD, first of all because it runs on Linux and secondly because the operating system in your main hard drive will not be active, the live CD can be used for data recovery too.

F-Secure emergency recovery live CD

Avira Rescue System: Linux based live CD to scan your computer for viruses, Avira antivirus database is updated several times a day, this is a good live antivirus CD to catch the latest exploit, once malware has been detected the live CD will automatically remove it saving yourself time reinstalling the whole operating system.

29 August, 2011
CloseTheDoor lists all UDP/TCP open ports

Most trojans and malware are remotely controlled by opening a port in your computer, this can be a non used port number or a disguised port normally used for something else, e.g. FTP. Firewalls should protect you from applications opening undesired ports but in reality firewalls give so many warnings that it is easy for a user to mistakenly authorise a connection. Some sites like Shields Up can scan your computer online and report on open ports, this is a good way to test your firewall quality, CloseTheDoor could be used to detect malware after an online port scanner comparing results to make sure that nothing awkward is going on.

CloseTheDoor lists computer open ports

This lightweight open source network tool will help you detect computer backdoors if they already exist, and prevent remote attacks on your machine, CloseTheDoor will listen on UDP/TCP ports in IPv4 and IPv6 and list what programs are associated with each connection displaying the listening port, protocol, PID and associated service, a right click on one of the connections gives the choice to locate the executable file that has opened the port and terminate the process or search Wikipedia and Google for more information on what the process does.

Visit CloseTheDoor homepage

21 August, 2011
RAMMap lists RAM memory processes

Knowing what is running on RAM memory when the system is live not only helps you find out computer load and what programs are taking up most of your expensive limited RAM memory, it also helps to spot malware, which often runs in RAM memory.

RAMMap RAM Memory Analyser

RAMMap is a 27Kb freeware from Microsoft Sysinternals that will give you exhaustive information on processes, priorities, physical pages and file details, everything is orderly displayed and classified in tabs, its advanced memory usage analysis is a little geeky, experts will love the detailed data reports that include memory load and path, newbies will benefit of this software by gaining a good understanding on how Windows manages and allocates RAM memory, if you are troubleshooting computer problems this program might be a convenient tool, memory snapshots can be saved as .rmp, a proprietary file extension unique to RAMMap.

Visit RAMMap Sysinternals homepage

Note: It only works in Windows Vista and higher.

17 August, 2011
Remotely monitor your home with a webcam using UGOlog

You can use a remote webcam to watch your pets at home, set up a virtual baby monitoring system or just for home surveillance while you are away, this is a good and cheap way to secure your house setting up a spy webcam and have it to activate on motion detection without the need for expensive cabled CCTV that can be spotted a mile away.

After signing up for a UGOlog account you will need to register your webcam with them, this is easy to do, any brand will work even IP webcams, there is no need for software downloads the setup process is carried out in UGOlog servers, once it is done you will be able to monitor your home or business in real time and record everything or schedule your webcam to start recording at a certain time or if the webcam has a motion sensor set it up to detect intruders, its RSS feed able to notify you of webcam changes can be the alarm warning you that someone just entered your home.

UGOlog provides you with a simple to use web browser interface to access the webcam broadcasting, recording and settings, the interface can manage more than one webcam and it includes a timeline and history archive which is stored at UGOlog servers, this can be accessed from any PC with internet access all you need is your UGOlog username and password.

Remote webcam surveillance UGOlog

It is possible to take webcam screenshots instead of continuous video surveillance recording, taking screenshots will save hard disk space when storing them. The free service is capped in data storage, with paid for options giving you more space allowing for more webcam snapshots to be taken per hour and more cameras to be connected.

Visit UGOlog homepage

9 August, 2011
Open source password generator Cryptnos

Cryptnos is a small open source program to create pseudo-random passwords out of cryptographic hashes (MD5, SHA-1, SHA-256, SHA-384, SHA-512, RIPEMD-160, Whirlpool and Tiger 1995 original), it associates a website domain name with the passphrase of your choice and combines it with a hashing algorithm with as many iterations as you like, to create a unique password as randomly as it is possible using software, the user is able to specify what characters the created password can contain, i.e. numeric, alphanumeric, and specify the password length.

Open source password generator CrypNos

Generated passwords are never stored and the parameters used to create them are kept encrypted with AES256 making it easy to securely export and import the settings to another computer, a platform independent Java version of Cryptonos is in future plans, at the moment you can use a Windows installable version that gives you help tooltips hoovering the mouse over the input boxes, an Android phone version without support for SD cards due to security reasons, and a webpage with configurable settings to decide on how to create your random passwords online without needing to install anything and on the go.

The program download page includes the software digital signature, a good practise that not many software distribution sites use, of use to check if anyone has modified the program you are about to download and changed it with another version full of malware.

BTW: The lion in the background is my desktop wallpaper and not part of the program 🙂

Visit Cryptnos homepage

7 August, 2011
3 methods to renew your computer IP Address

The most common way to access the Internet for home users is through DHCP (Dynamic Host Configuration Protocol) a standard protocol ( RFC 1531 ) that assigns dynamic (changing) IP addresses to the host, this is done automatically and saves the ISP the need for human intervention, a computer can get a new IP address every time it reconnects to the network, DHCP keeps a central database with the IPs that have been assigned to avoid giving the same IP to different devices which would cause network problems with data packets not knowing what way to go.

Just because your old IP has been given away to someone else this doesn’t mean that your activities have not been logged and you are not traceable, a database with the customer ID linking him to the leased IP with times and dates at which that particular IP was assigned to the customer will be kept, either for troubleshooting or legal reasons, some ISPs could keep this information for years, possibly no more than two as data retention laws, where they exist, do not go that far.

Renew a computer IP disconnecting your router

A DHCP allocated address can be renewed wherever your ISP configuration servers decide it needs to be renewed, even while you surf the Internet (unconventional), or you can force your ISP to give you a new IP. Disconnecting the router (on/off button) for a couple of minutes will finish the IP lease,you are likely to get a new IP when you reconnect to the network and your old IP will have been assigned to someone else.

If you do not get a new IP address after disconnecting and reconnecting your router from the network, try to leave your router disconnected for longer, a few hours to make sure, best done overnight, your chances of being given a new IP by your ISP (DHCP) will improve the longer your device has been disconnected.

Renew a computer IP to using Windows cmd

To renew your computer’s IP address in Windows launch cmd, go to Windows search and type in cmd or command.com, make sure to run cmd as administrator otherwise you won’t be able to get a new IP.

Windows cmd command launch

At the command prompt type: ipconfig (click Enter) if you have more than one device connected to your router (wireless and Ethernet) type ipconfig /all (Optional step to see your current IP address)

ipconfig /all shows all connected media

At the command prompt type: ipconfig /release (click Enter)>>>>This step will disconnect you from the network and your computer IP address will show as “Media disconnected”

ipconfig release disconnect IP

At the command prompt type: ipconfig /renew (click Enter) >>>>Now exit (type exit and click Enter) wait a couple of minutes for a new IP to be assigned to your computer

Windows ipconfig /renew gets new IP

Renew computer IP using the router interface

Login into router administration launching your browser and typing in the router IP (normally http://192.168.1.1/), the router user and password could be admin:admin or something else depending on brand, enter your router brand on an Internet searcher to find out the default password.

Once inside the router management interface release your IP, every manufacturer has a different way to do this, there is no golden rule about where to find this setting, when you have found it, turn off the router, switches and all network cards, leave it off overnight and switch it back on the next day remembering to enter the router management interface once again to renew your computer IP.

Renew computer IP troubleshooting

Some ISPs assign IPs based on a device MAC address, in those cases the only for you to get a new IP will be changing your network card or using special software to fake your computer MAC address.

If you type ipconfig at the command prompt and see that your IP starts with 169.254.*.* then you are not connected to the Internet, Windows will assign you a 168.254.*.* IP when the computer can not connect to a DHCP server, this IP is called an APIPA address (Automatic Private IP Addressing).

If after disconnecting your router from the network overnight and reconnecting next day in the morning you still get the same IP call your ISP and ask them how long do you need to be disconnected in order to renew the computer IP.

Try disabling your firewall and antivirus if ipconfig /renew does not work as it can cause problems renewing your IP by blocking ports, in rare occasions it could also be that your network card drivers need to be updated.

3 August, 2011