Bypassing Client-Side Filtering

When a user input something in the website such as adding a comment or uploading a file, these things can be verified for the validity and authenticity by using two methods. Client-Side or Server-Side filtering. When it is Client side, the filtering happens in the browser itself. Where as in Server side, the user input is sent back to the Server and then the server will validate the user input. Based on that, the user can successfully input something in to the website.
Server side filtering are comparatively harder to figure out as the code won't be passed to the end user. But when in comes to Client side filtering, the user/attacker can easily find out the filtering methods and may bypass the filtering using various methods.

There are four major ways to bypass the client-side file upload filter:

Turn off JavaScript in your browser . Most of the filtering check is accomplished by using a java script. So disabling the JavaScript in your browser may disable any kind of checks. But this may not be mostly successful as the JavaScript may possess additional features that affects the site functionality.
Intercept and modify the incoming page. When the page is loaded, there will be additional scripts to verify the uploading file. The script can be in java, which will look for the file extension, or magic number, file size etc. If any of these conditions doesn't met, then the file uploaded might be unsuccessful. An easier way is to delete such filtering from the scripts or sometimes, deleting the entire script might work as well.
Intercept and modify the file upload.When the file is uploaded, intercept the packet and edit the parameters such as MIME, so that the file filtering can be bypassed. You can perform this using tools such as Burp Suite.
Send the file directly to the upload location. If you are able to find out the upload location, you can perform a POST function to upload the file directly to the site location.

RUST error: linker `link.exe` not found

While compiling Rust program in a windows environment, you may encounter the error : linker `link.exe` not found. This is because of the absence of the C++ build tools in your machine. For compiling Rust programs successfully, one of the prerequisites is the installation of the Build Tools for Visual Studio 2019. Download the Visual Studio 2019 Build tools from the Microsoft website. After the download, while installing the Build tools, make sure that you install the required components (highlighted in Yellow) This will download around 1.2GB of required files. Once everything is successfully installed, reboot and re-run your rust program and it will compile successfully. Read More on RUST Hello World Rust Program : Code explained RUST Cargo Package Manager Explained Data Representation in Rust.

Cisco ASA: Disable SSLv3 and configure TLSv1.2.

For configuring TLS v1.2, the ASA should run software version 9.3(2) or later. In earlier versions of ASA, TLS 1.2 is not supported.If you are running the old version, it's time to upgrade. But before that i will show you the config prior to the change. I am running ASA version 9.6.1 Now ,set the server-version to tlsv1.2, though ASA supports version tlsv1.1, its always better to configure the connection to more secure. Server here in the sense, the ASA will be act as the server and the client will connect to the ASA. #ssl server-version tlsv1.2 set the client-version to tlsv1.2, if required. #ssl client-version tlsv1.2 ssl cipher command in ASA offers 5 predefined security levels and an additional custom level. #ssl cipher tlsv1.2 high we can see the setting of each cipher levels using #show ssl cipher command. Now set the DH group to 24, which is the strongest offered as of now in the ASA. #ssl dh-group group24 An

Download Microsoft Office 2019 offline installer.

When you do malware analysis of documents or office files, it is important to have Microsoft Office installed in your Lab machine. I am using flare VM and it doesn't comes with MS Office. Since Microsoft is promoting Microsoft 365 over the offline version, finding the offline installer is not that easy. Here is the list of genuine Microsoft links to download the office .img files. Download Microsoft Office 2019 Professional Plus : https://officecdn.microsoft.com/db/492350F6-3A01-4F97-B9C0-C7C6DDF67D60/media/en-US/ProPlus2019Retail.img Download Microsoft Office 2019 Professional : https://officecdn.microsoft.com/db/492350F6-3A01-4F97-B9C0-C7C6DDF67D60/media/en-US/Professional2019Retail.img Download Microsoft Office 2019 Home and Business : https://officecdn.microsoft.com/db/492350F6-3A01-4F97-B9C0-C7C6DDF67D60/media/en-US/HomeBusiness2019Retail.img Download Microsoft Office 2019 Home and Student : https://officecdn.microsoft.com/db/492350F6-3A01-4F97-B9C0-C7C6DDF67D60/media/en-U

How to Install Netmiko on Windows?

Netmiko, developed by kirk Byers is an open source python library based on Paramiko which simplifies SSH management to network devices and is primarily used for network automation tasks. Installing Netmiko in linux is a matter o f one single command but if you need to use Netmiko in your Windows PC, follow this process. 1) Install the latest version of Python. 2) Install Anaconda, which is an opensource distribution platform that you can install in Windows and other OS's (https://www.anaconda.com/download/) 3) From the Anaconda Shell, run “ conda install paramiko ”. 4) From the Anaconda Shell, run “ pip install scp ”. 5) Now Install the Git for Windows. (https://www.git-scm.com/downloads) . Git is required for downloading and cloning all the Netmiko library files from Github. 6) From Git Bash window, Clone Netmiko using the following command git clone https://github.com/ktbyers/netmiko&#8221 7) Once the installation is completed, ch

PrintNightmare (CVE-2021-1675) PoC exploit Walkthrough

I am not an exploit developer but was interested to see how this vulnerability can be exploited. So i tried to replicate the infamous PrintNightmare vulnerability using the following PoCs ( https://github.com/cube0x0/CVE-2021-1675 ) and ( https://github.com/rapid7/metasploit-framework/pull/15385 ) However i had trouble with the new metasploit module (auxiliary/admin/dcerpc/cve_2021_1675_printnightmare) and i couldn't able to exploit the machine successfully. So i tried the second PoC from cube0x0. This one has done the magic. I just followed the guidelines with couple of tweaks. First of all, i installed the impacket (cube0x0 version) which will install the required modules and files. After that i set up a samba share with an anonymous login. This is required for hosting the dll file. I edited the smb.conf with the following settings. [global] map to guest = Bad User server role = standalone server usershare allow guests = yes idmap config * : backend = tdb s

Google Cloud : Basic Cloud Shell commands

Google Cloud resources can be managed in multiple ways. It can be done using Cloud Console, SDK or by using Cloud Shell. A few basic Google Cloud shell commands are listed below. 1) List the active account name gcloud auth list 2) List the project ID gcloud config list project 3) Create a new instance using Gcloud shell gcloud compute instances create [INSTANCE_NAME] --machine-type n1-standard-2 --zone [ZONE_NAME] Use gcloud compute machine-types list to view a list of machine types available in particular zone. If the additional parameters, such as a zone is not specified, Google Cloud will use the information from your default project. To view the default project information, use gcloud compute project-info describe 4) SSH in to the machine gcloud compute ssh [INSTANCE_NAME] --zone [YOUR_ZONE] 5) RDP a windows server gcloud compute instances get-serial-port-output [INSTANCE_NAME] --zone [ZONE_NAME] 6) Command to check whether the server is ready f

Unable to locate package linux-headers / E: Unable to locate package linux-headers-5.10.0-kali5-amd64

While compiling programs, you may encounter this particular error. E: Unable to locate package linux-headers-5.10.0-kali5-amd64 I encountered this while compiling a C code. To fix this, i first updated my Kali machine (v2020.2a). sudo apt update -y && apt upgrade -y && apt dist-upgrade Rebooted. Then installed the headers. sudo apt install linux-headers-$(uname -r)

Difference between Azure management groups, Subscriptions and Resource groups

image courtesy : https://docs.microsoft.com Azure management groups help you manage your Azure subscriptions by grouping them together. If your organization has many subscriptions, you might need a way to efficiently manage access, policies, and compliance for those subscriptions. Azure management groups provide a level of scope above subscriptions. Azure subscriptions help you organize access to Azure resources and determine how resource usage is reported, billed, and paid for. Each subscription can have a different billing and payment setup, so you can have different subscriptions and plans by office, department, project, and so on. Resource groups are containers that hold related resources for an Azure solution. A resource group includes those resources that you want to manage as a group. You decide which resources belong in a resource group based on what makes the most sense for your organization. reference : https://docs.microsoft.com

What is a Gratuitous ARP? How is it used in Network attacks?

Many of us encountered the word "Gratuitous" while exploring the network topic on ARP, The Address Resolution Protocol. Before explaining Gratuitous ARP, here is a quick review on how ARP works. ARP provides IP communication within a Layer 2 broadcast domain by mapping an IP address to a MAC address.For example, Host B wants to send information to Host A but does not have the MAC address of Host A in its ARP cache. Host B shoots a broadcast message for all hosts within the broadcast domain to obtain the MAC address associated with the IP address of Host A. All hosts within the same broadcast domain receive the ARP request, and Host A responds with its MAC address. We can see the ARP entries on our computers by entering the command arp -a . So, back to the topic on what is a Gratuitous reply, here is a better explanation. Gratuitous arp is when a device will send an ARP packet that is not a response to a request. Ideally a gratuitous ARP request is an ARP request packe

Recovery Procedure: Alcatel-Lucent Omni-Switch not booting AOS: Going to Mini-boot prompt.

Problem: Switch not booting AOS; Going to Mini-boot prompt. Model: Alcatel-Lucent OS6850 [Note:The same procedure might be applicable for different models of Omni-Switches, However, for this illustration, i have used OS-6850 ] Reason: This problem may occurs due to corrupt AOS image files or misconfigured boot parameters. Hence switch cannot boot the images properly and will go to Mini-boot prompt. Work Around: [Note: This zmodem procedure consumes a lot to time to finish the process.] 1.) Power off your OS6850 2.) When you switched it back on, stop it before the Miniboot (there is some counter counting down from 4). Press Enter to break. 3.) You will have the following prompt " => " 4.) Enter " setenv baudrate 115200 ”. Increasing baudrate helps to increase the data transfer speed using zmodem. 5.) Enter " saveenv " 6.) Enter " boot " 7.) The switch should run now in baud rate 115200 (so you have to change your clients ter