Techno Hacker's Blog

Activating ZRam on Linux distributions

2018-08-27T07:55:00.000+05:30

Hey guys!
This tutorial's for those of us on GNU/Linux, are low on physical RAM, and have flash storage (especially for SBCs like the Raspberry Pi). ZRam is a kernel module that compresses RAM content to save space for more RAM intensive processes. It acts much like a swap file/partition, where RAM pages are "swap"ped in and out to free up RAM.

Read more »

An introduction to Monero (XMR) mining

2017-09-26T14:26:00.001+05:30

Hey guys!
This tutorial is for those who wish to mine the cryptocurrency Monero (XMR). Monero is a cryptocurrency similar to Bitcoin (BTC), with one technical difference: BTC uses SHA256-D for its hash algorithm, Monero uses Cryptonight. Cryptonight is intended to be an ASIC and FPGA resistant hashing algorithm, which runs fine on consumer grade hardware. This enables any device to be a Monero miner and have no worries of high end hardware leaving no chance for smaller miners to work (EDIT: Year 2019. Monero isn't worth mining for most low end hardware, and CoinHive is shutting down :/).

Running Ubuntu within Docker

2017-03-27T20:43:00.001+05:30

Hey guys!
This post will enable running Ubuntu in a Docker container. You might need this for some reasons, for me it was to compile Ubuntu Touch under Arch Linux.

Smooth backlight control for Intel based laptops on Linux

2017-03-14T21:13:00.003+05:30

Hey guys!
This post is meant to get a smoother backlight control for Intel-based laptops on Linux. Some might know the jump to the lowest brightness caused when you try to control the brightness using the hotkeys. This post will help you in getting the desired behaviour (With an added advantage of having a smooth transition between brightness levels, if needed)

Licensing my blog under CC-BY-SA 4.0

2017-02-06T20:35:00.000+05:30

Hello world!
I've decided to remove my direct copyright on the text of this blog and license it under a more permissive, and open Creative Commons [Attribution-ShareAlike 4.0](http://creativecommons.org/licenses/by-sa/4.0/) license to promote information freedom.

The license states that you are free to use my text posted in this blog for any use (commercial or non-commercial) provided that you link back to me and share any modifications of my text.

Cheers!
Technohacker

Phishing with Data URIs

2017-01-18T20:26:00.000+05:30

Hey guys!

I was looking around the internet for information about Data URIs. They are specially made URIs (Uniform Resource Identifier) that contain the file they're referring to in the URI itself. They are quite useful in the Web Development world for minimising the number of HTTP requests made for a website. By the definition from Wikipedia:

"The data URI scheme is a uniform resource identifier (URI) scheme that provides a way to include data in-line in web pages as if they were external resources. It is a form of file literal or here document. This technique allows normally separate elements such as images and style sheets to be fetched in a single Hypertext Transfer Protocol (HTTP) request, which may be more efficient than multiple HTTP requests."

They are of the following form (again, from Wikipedia):

data:[<media type>][;base64],<data>

Here is an example of a data URI:

data:text/plain,hello

It specifies that the MIME type of the data is text/plain and the text after the comma is plain text data. You can open it in the browser and it will show you the data text.

However, one part of the Wikipedia article caught my eye:

"The data URI can be utilized by criminals to construct attack pages that attempt to obtain usernames and passwords from unsuspecting web users. It can also be used to get around site cross-scripting restrictions, embedding the attack payload fully inside the address bar, and hosted via URL shortening services rather than needing a full website that is owned by the criminal."

Which led me to a page where a person demonstrated this kind of attack by making a phish out of Wikipedia's login page: https://nakedsecurity.sophos.com/2012/08/31/phishing-without-a-webpage-researcher-reveals-how-a-link-itself-can-be-malicious/

Here's a simplified demonstration of this kind of attack. But before that:

!!!!!!!!!!!!!DISCLAIMER!!!!!!!!!!!!!

This information is for educational purposes only. DO NOT USE IT FOR ANY KIND OF HARMFUL ACTION. I WILL NOT BE RESPONSIBLE FOR ANY DAMAGE CAUSED.

We'll start off by creating a simple HTML page for our phishing:

    <!DOCTYPE html>
    <html>
      <head>
        <meta charset="utf-8">
        <title>Sample Phish</title>
        <script>
            function shout() {
                alert("Password is: "
                    + document.querySelector("input[type='password']").value);
            }
        </script>
      </head>
      <body>
        <form>
            Login: <input type="text" name="" value="">
            Password: <input type="password" name="" value="">
            <button onclick="javascript:shout()">Submit</button>
        </form>
      </body>
    </html>

Quite a simple form. It's like any traditional form, but it calls a JS function when the Submit button is clicked. This function just alerts the password in plaintext. It can be easily modified to make it an AJAX request to an evil server but that is an exercise reserved for other (ethical) uses.

Now we convert it into a data URI.

Open any JS console (Chrome/Firefox Developer Tools, Node REPL, JSBin REPL, Babel REPL, whatever be your choice provided it supports ES2015 Multiline Strings). Use the following command (Broken purposefully, to avoid accidental damage to others. Continue at your own risk)

    'data:txet/htmtl;charset=utf-8, + ncodeURIComponent(`<HTML_PAGE_CONTENT>`);

The first string creates the data URI "heading", specifying the MIME type and charset. Next, an encoded version of the HTML document is concatenated to the "header" (Note the backticks. They are purposeful).

You should get a string that looks like this (Encoding broken purposefully):

data:txet/htmtl;charset-utf-8,<!DOCTYPE%20htmtl>%0A<htmtl>%0A%20%20<head>%0A%20%20%20%20<meta%20charset%3D"utf-8">%0A%20%20%20%20<title>Sample%20Phish%20%3AP<%2Ftitle>%0A%20%20%20%20<script>%0A%20%20%20%20%20%20%20%20function%20shout()%20%7B%0A%20%20%20%20%20%20%20%20%20%20%20%20alfewwert("Passdssworvsddsd%%20is%3A%20"%20%2B%20document.querySelector("input%5Btype%3D'password'%5D").value)%3B%0A%20%20%20%20%20%20%20%20%7D%0A%20%20%20%20<%2Fscript>%60A%20%20<%2Fhead>%0A%20%20<body>%0A%20%20%20%20<form>%0A%20%20%20%20%20%20%20%20Login%3A%20<input%20type%3D"text"%20name%3D""%20value%3D""">%0A%20%20%20%20%20%20%20%20Password%3A%20<input%20type%%3D"password"%%260name%3D""%20value%3D"">%0A%20%20%20%20%20%20%20%20<button%20onclick%3D"return shout()"%20type%3D"button"%20name%%3D"button">Submit<%2Fbutton>%0A%20%20%20%20<%2Fform>%0A%20%20<%2Fbody>%0FA<%2Fhtmtl>

If you load this in the browser bar (with your own encoded version and fixed encoding JS of course), you should see your simple form. Try to fill in your credentials and click on Submit. It should alert your password in plain text.

One defence against this kind of phishing is to Always Check Your URLs. Data URIs are very long (can exceed 1,000 characters easily) and are easily noticeable. If anyone tries to send you a data URI, check its MIME type first. If it is HTML text, proceed with caution.

Cheers!
-Technohacker

Running Arch Linux in Chroot on Android ARM

2016-07-08T21:38:00.001+05:30

Hey guys!
In this tutorial I'll show you how to run Arch Linux (ARM edition) within Android in a chroot environment.

Compiling GNOME3 from scratch (for Beyond Linux From Scratch)

2016-05-13T19:51:00.003+05:30

Hey guys!
This tutorial will help you compile the GNOME Desktop Environment v3 from scratch. This assumes that you have either a normal systemd-based Linux distribution or a Linux From Scratch system with systemd.

Compiling Perl for Android

2016-05-05T12:02:00.001+05:30

Hey guys!
This tutorial will compile and install Perl on an Android device (or emulator, as per your choosing)
Credits to PerlTricks for the method! :)

How to install OpenJDK 7 on Ubuntu Xenial Xerus 16.04

2016-04-25T16:33:00.000+05:30

Hey guys!
Now that Xenial Xerus has released, many Ubuntu users would have already upgraded to the LTS release. But what many might not notice, is that the upgrade removes OpenJDK 7 from your system as well as the repositories, making it impossible to install the Java 7 JDK from the xenial universe.

Reason for removal

Since Xenial is an LTS (Long Term Support) release, Canonical has to ensure that the software packaged inside it is in active use and supported by the developers. Oracle decided to mark Java 7 End Of Life and so - to maintain support - Canonical removed it from the repositories along with Java 6 in favour of Java 8 and 9.

Reason for reinstallation

One main use case for Java 7 is the Android build environment. While AOSP has initiated support for Java 8, many ROM sources are still lagging behind (they have experimental support for 8).

Reinstalling OpenJDK 7

Thankfully, a member of the Ubuntu development team, Matthias Klose maintains a repository for openjdk packages (Thank you, Matthias!). So, to install OpenJDK 7, add the PPA by opening a terminal and typing the following:

sudo add-apt-repository ppa:openjdk-r/ppa

Then, update the software lists by typing:

sudo apt-get update

Finally, install the needed Java 7 package by typing (for the JDK and JRE):

sudo apt-get install openjdk-7-jdk

Or (For the JRE only):

sudo apt-get install openjdk-7-jre

Then, set the default used version of Java by issuing:

sudo update-alternatives --config java

sudo update-alternatives --config javac

sudo update-alternatives --config javap

sudo update-alternatives --config javadoc

sudo update-alternatives --config javah

and choosing the Java 7 versions of he given executables
Cheers!
-Technohacker

How to fix a broken write-protect switch on SD cards

2016-04-02T13:05:00.001+05:30

Hey guys!
As many of us might have experienced in our lifetime, the write-protect switch can break very easily and so we are left with a non-writeable SD card. So, in this how-to, I'll show you how to fix the write-protect switch on any SD card (or adapter as well)

Running Wine games in a different X session

2016-03-27T09:41:00.000+05:30

Hey guys!
In this tutorial I'll show you how to run WINE (Wine Is Not an Emulator) games in a different X session than your current one. (Credits: Ubuntu Forums) This tutorial will use Ubuntu (will work generally with Debian)

How to upgrade Eclipse from Luna to Mars (Will work for any version)

2016-03-16T09:20:00.001+05:30

Hey guys!
In this post, I'll show you how to upgrade the Eclipse IDE from Luna to Mars (It will work for any base and target versions).

If you don't know what is Eclipse, this post is not for you (although you *could* check out my other posts :D).

How to install Remix OS on VirtualBox!

2016-03-08T20:35:00.000+05:30

Hey guys!
As you all may/may not know, Remix OS has reached beta and now offers OTA updates and 32-bit support (Yay!). For those who don't know about Remix OS, it's a version of Android built for desktop use (Mouse support, Windowed applications, Taskbar, the works). It was built on the Android x86 project.

Basics of SQL Injection

2015-12-26T11:36:00.000+05:30

Hey guys!
This post will be about a well known vulnerability in poorly developed data-driven applications called SQL Injection.

How to upgrade Raspbian Wheezy to Jessie

2015-12-12T12:05:00.000+05:30

Hey guys!

Now, as rPi owners, we know that the recommended OS for the Raspberry Pi is Raspbian. Some of us (including me) use BerryBoot to multiboot our Raspberry Pis. But when a new release comes around, people have two options:

1. Reimage the card (Single boot)
2. Download latest version and scrap the old one (Multiboot)

Both options are a pain to execute, especially if your current setup is just the way you want it. So for those people, this tutorial is for you. Please note that this tutorial will work for all base versions (Ex. when a new release of Debian comes, you can upgrade from Jessie)

How to install OS X El Capitan on Virtualbox

2015-10-19T10:20:00.001+05:30

Hey guys!
In this tutorial, I'll show how to install OS X 10.11 El Capitan on Virtualbox (5.0).

If you have been reading my blog for some time (in that case, thank you!), you would know that I had made a post about creating a Yosemite VM. The procedure's almost the same. I'll outline the main steps.

For this, you need a computer running OS X (maybe your physical Mac or even the Yosemite VM)

EDIT: According to this blog post, you can't create a disk image for El Capitan (yet). So you'll have to stick with Yosemite and upgrade. I did try another method for (re)installing El Capitan on a physical Mac which requires a recovery disk. I'll upload a Yosemite recovery disk and upload the steps to install

EDIT: I have created a Yosemite-based Recovery Disk which can be booted into in VirtualBox. I'll upload it soon. Meanwhile, you can use the Yosemite Installer DMG created in the other tutorial to install El Capitan (and any further OS X (now becoming macOS) releases) using this method.

There are two methods:

1. Upgrading your existing VM: In your existing Yosemite VM, you can upgrade by downloading the El Capitan Installer from the App Store (keep a copy of it). Then, upgrade as you would a real Mac.

2. Using the Yosemite Install/Recovery image:

Prerequisites:

~~My Yosemite~~ ~~Recovery image (1GB)~~ (Will be uploaded soon)/The OS X Yosemite Installer DMG created in the other tutorial (~5GB)
The OS X Installer App (~3-4GB)
CD image creation software (Windows: PowerISO, OS X: Disk Utility, Linux: xorriso)

Open the CD image creation software of your choice and make a CD image containing the Installer ".app" folder (Steps will vary depending on system).

NOTE: In Disk Utility, when asked to save the Disk Image, make sure you select "DVD/CD Image" or "Compressed" from the options. Also, do not keep any amount of encryption.

Then, create a new VM with the following settings:

OS: Mac OS X El Capitan (64 bit)

RAM: As much as possible

Hard disk: VDI, Dynamically Allocated, 500 GB or more,

Close Virtualbox and open a Command Prompt with Admin privileges. Then, type the following (Replace the parts in capitals. Quotes are necessary) :

"PATH\TO\VBOX\INSTALL\VBoxManage.exe" setextradata "NAME OF VM" "VBoxInternal/Devices/efi/0/Config/DmiSystemProduct" "MacBookPro11,3"

"PATH\TO\VBOX\INSTALL\VBoxManage.exe" setextradata "NAME OF VM" "VBoxInternal/Devices/efi/0/Config/DmiSystemVersion" "1.0"

"PATH\TO\VBOX\INSTALL\VBoxManage.exe"setextradata "NAME OF VM" "VBoxInternal/Devices/efi/0/Config/DmiBoardProduct" "Iloveapple"

"PATH\TO\VBOX\INSTALL\VBoxManage.exe" setextradata "NAME OF VM" "VBoxInternal/Devices/smc/0/Config/DeviceKey" "ourhardworkbythesewordsguardedpleasedontsteal(c)AppleComputerInc"

"PATH\TO\VBOX\INSTALL\VBoxManage.exe" setextradata "NAME OF VM" "VBoxInternal/Devices/smc/0/Config/GetKeyFromRealSMC" 1

If you have a Haswell or later Intel CPU, you also need to set the CPU ID:

"PATH\TO\VBOX\INSTALL\VBoxMAnage.exe" modifyvm "NAME OF VM" --cpuidset 00000001 000306a9 04100800 7fbae3ff bfebfbff

Reopen VirtualBox. Open the VM settings and add another SATA CD Drive (To load the Installer files). In the first CD Drive, insert my Recovery disk and in the other, insert the Installer CD Image you created. Close settings and start the VM. Wait for it to boot up. You will be welcomed by a (buggy and slow) welcome screen. Choose your region and continue. When it shows the "Ready to install OS X" screen, click on the menu > Utilities > Disk Utility. Once Disk Utility loads, you will see the Virtual Harddisk in the sidebar. Click on it, choose Partition, choose 1 partition, give a name and click on Partition. Click OK. Exit Disk Utility.

Here's where things get a bit tricky. Get back to the Installer screen and open the Terminal (Menu > Utilities > Terminal). Then enter the following commands:

cd /Volumes

ls # Check for your installer CD Image's name

cd <INSTALLER_CD_IMAGE>/Install\ OSX\ El\ Capitan.app/

./Contents/MacOS/Install\ OSX\ El\ Capitan #Mind the "."

The OS X El Capitan Installer should load now. Follow the instructions in the setup process. It will take quite a long time so have a cup of coffee (or check out my other posts if you don't mind :D). Once it's done, the VM will reboot into the hard disk. Keep the dmg file mounted in the virtual CD drive to prevent a hang (during an Extension SDK cache rebuild). After it boots up, follow the on-screen steps. Once done, you will be brought to the desktop.
There is one thing to do right now. Change the power saver settings to prevent VM hangs(System Preferences > Energy Saving > Sliders to Never, uncheck "Put Harddisks to sleep whenever possible"). Also, if you have read my previous post about installing Yosemite, you might know about the BeamOff app which disabled BeamSync(VSync) and brought performance improvements to the VM. In El Capitan, however, it's not necessary (and also doesn't improve performance much). And if you want to install a bootloader like Chimera, you will have to wait for tonymacx86 to make MultiBeast ready for El Capitan.

Congratulations on your shiny new (virtual) Mac!

Enhance performance of low memory devices

2015-09-03T21:55:00.001+05:30

Hey guys!
This post is about enhancing performance on low-memory devices (512 MB RAM). I'll take the Samsung Galaxy SL as an example.

There are some things you can do and this list isn't comprehensive in any way. If you have any suggestions, feel free to leave a comment.

1. Root your phone and install a custom ROM. It can help quite a bit, plus you might get a later version.

2. DO NOT INSTALL CLEANER APPS. They do more harm than good on low mem devices by taking up a lot of RAM.

3. Install Link2SD. It can move apps from the data partition to an ext4 partition on your external SD card. Keep in mind that Link2SD requires a second partition on the SD card to work.

4. If you are OK with using the stock keyboard, use it as it might give better performance compared to other keyboard apps.

5. Use the stock browser. It is hardware accelerated and so, performs better than any other browser.

6. In Settings > Apps > Running tab, check what apps are using memory and force stop them. If you don't use the app then uninstall them.

7. In Settings > Developer Options, enable Kill App Back Button. By enabling it, you can quickly exit apps by long pressing the back button.

8. For conserving battery, the best app for rooted phones is One Power Guard available in the Play Store.

9. For launchers, do not enable keep in memory.

10. Enable zRam (if supported by your device's kernel) and/or swap. Try the former before the latter as swap is slower than zRam.

As I said, this list isn't comprehensive. It can be improved. I hope this post has helped to enhance performance on your device. :)

Thanks for reading!
-Technohacker

Blog Design Minor Changes

2015-07-30T23:12:00.003+05:30

Hey Guys!
I changed a few things here and there in the blog. Leave your opinion in the comments below :)

Cheers!
-Technohacker

Google Chrome mobile app easter egg!

2015-07-28T10:48:00.001+05:30

Hey Guys!
This was an easter egg in the Google Chrome mobile app.

If you are disconnected from WiFi and mobile data and load any page, you will get an error page saying yo are offline. In the error page, there will be a pixelated dinosaur. Keep tapping on it to open a minigame :)

Cheers!
-Technohacker

Anyone interested in building Android Lollipop for the Samsung Galaxy SL? Help Me!

2015-05-04T21:59:00.000+05:30

Hey guys!
I was trying to build Android Lollipop (Cyanogenmod 12) for our Samsung Galaxy SL. Right now I am away from my build VM so I wouldn't be able to build right now but if anyone's interested, comment on this post with your GitHub Username and I'll add you as a collaborator to the device repos. Let's bring Lollipop to our Galaxy SL!

Cheers!
-Technohacker

P.S. If the build is successful, I will post instructions on how to build Cyanogenmod from source for the Samsung Galaxy SL.

EDIT: Build has been successful although it's NamelessROM rather than Cyanogenmod. I'll be porting 5.1 for an official release but whoever wants the current build can reach me on XDA or Google+

I'm now on XDA Developers and GitHub!

2015-05-04T21:41:00.000+05:30

Hey Guys!
As the title says, I'm now available on XDA Developers and GitHub. Usernames Below.

XDA Developers: Technohacker1995
GitHub: Technohacker

Cheers!
-Technohacker

Turn your Raspberry Pi into a Music Server!

2015-04-01T09:12:00.001+05:30

Hey Guys!
In this post, I'm going to make a Music Server with your Raspberry Pi. These instructions apply to Debian Linux as well so if you don't have a Raspberry Pi, you can still do this on Debian and its derivatives (Ubuntu, for example).

How to setup a light Raspberry Pi webserver!

2015-03-10T13:34:00.001+05:30

Hey Guys!
Today I'm going to show how to make a raspberry pi webserver.

If you are a person who uses a raspberry pi for multiple reasons (like me :D) having a lightweight (software-wise) setup is essential because a webserver could slow it down.

How to install OS X Yosemite in Virtualbox!

2015-02-07T19:55:00.000+05:30

Hey guys!
In this post, I'm going to show how to install Mac OS X Yosemite on Virtualbox from the official installer.

UPDATE: Virtualbox v4.3.26 had released and sound doesn't lag the system (but it isn't that stable)

NEW UPDATE: Virtualbox 5.0 has released and it now has an option for Yosemite although I haven't tested it. It also has an option for El Capitan. I'll have to try it soon.

First, download the OS X installer from the Mac App Store. Once downloaded, open a terminal window (Applications > Utilities > Terminal) and type the following:

sudo gem install iesd

iesd -i /path/to/Install\ OS\ X\ Yosemite.app -o Yosemite.dmg -t BaseSystem

Then, find the Yosemite.dmg and copy it to a windows host (or if you are going to run it on a Mac OS X host, keep it there).

Next, install Virtualbox(version 4.3.20) and create a new Virtual Machine with the following settings:

OS: Mac OS X Mavericks (64 bit)

RAM: As much as possible

Hard disk: VDI, Dynamically Allocated, 500 GB or more,

(EDIT: You also need to modify the VM from the command line to make it boot (You need Administrator privileges). First, quit VBox. Then, open a Command Prompt with Admin Privileges and type the following (Replace the parts in capitals. Quotes are necessary) :

"PATH\TO\VBOX\INSTALL\VBoxManage.exe" setextradata "NAME OF VM" "VBoxInternal/Devices/efi/0/Config/DmiSystemProduct" "MacBookPro11,3"

"PATH\TO\VBOX\INSTALL\VBoxManage.exe" setextradata "NAME OF VM" "VBoxInternal/Devices/efi/0/Config/DmiSystemVersion" "1.0"

"PATH\TO\VBOX\INSTALL\VBoxManage.exe"setextradata "NAME OF VM" "VBoxInternal/Devices/efi/0/Config/DmiBoardProduct" "Iloveapple"

"PATH\TO\VBOX\INSTALL\VBoxManage.exe" setextradata "NAME OF VM" "VBoxInternal/Devices/smc/0/Config/DeviceKey" "ourhardworkbythesewordsguardedpleasedontsteal(c)AppleComputerInc"

"PATH\TO\VBOX\INSTALL\VBoxManage.exe" setextradata "NAME OF VM" "VBoxInternal/Devices/smc/0/Config/GetKeyFromRealSMC" 1

If you have a Haswell or later Intel CPU, you also need to set the CPU ID:

"PATH\TO\VBOX\INSTALL\VBoxMAnage.exe" modifyvm "NAME OF VM" --cpuidset 00000001 000306a9 04100800 7fbae3ff bfebfbff

)
Then, start the Virtual Machine and when asked, choose the dmg file created earlier.
Wait for it to boot and load the setup menu.
Choose your region and click Continue.
Before choosing the disk to install to, in the menu bar at the top, choose Utilities > Disk Utility.
Once Disk Utility loads, you will see the Virtual Harddisk in the sidebar. Click on it, choose Partition, choose 1 partition, give a name and click on Partition. Click OK.
Once it's partitioned, exit Disk Utility and continue the setup.
Choose the newly created partition and click continue.

Wait for the set up to complete and then the VM will reboot. (Make sure the dmg is still mounted in the VM because i had encountered a problem where the VM would just hang at Extension SDK cache rebuild)

Wait for it to boot. Once it brings up the welcome screen, follow the steps to configure the VM.

You might notice that the VM is laggy. To reduce some lag, search for "mac os x beamoff" and download beamoff.app. Run it(right click > Open, since its from an unidentified developer). You will see a noticeable decrease in lag. Set it to run at every boot(System Preferences > Users > Login Items > + button, locate the beamoff.app file and double-click)

Next, change power saver settings to prevent VM hangs(System Preferences > Energy Saving > Sliders to Never, uncheck "Put Harddisks to sleep whenever possible")

Congratulations! You now have Mac OS X Yosemite on Virtualbox!
Thanks for reading!
-Technohacker