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ms08-067 exploitation to hack Windows XP

Hello aspiring ethical hackers. In this article, we will see how to exploit ms08-067 vulnerability to hack Windows XP. As our readers may already know by now, ms08-067 is a vulnerability in Windows 2000, Windows Server 2003 and Windows XP. It is a critical vulnerability that allows remote code execution on the target Windows system by sending a specially crafted RPC request to it.

This vulnerability doesn’t require any authentication or even user interaction on the target side. That’s the reason why it is ubiquitous in any ethical hacking course. We have exploited this vulnerability recently in our February 2021 Issue. But that was done using without Metasploit.

In this article, we will do this with Metasploit. For this, we have chosen our target as Windows XP SP2 and our Attacker system as Kali Linux. Most of the Antivirus ended their support to Windows XP SP2 (Windows XP SP3 is the minimum supported version. Even Real world systems running Windows XP SP2 are running without Anti Virus.)

So Nmap scan revealed a Windows target as shown below.

Start Metasploit and load the ms08_067 module.

Set all the required options and use check command to see if the target is indeed vulnerable.

The target is indeed vulnerable. Now, execute the module as shown below.

ms08-067

As readers can see, we successfully got a meterpreter session with SYSTEM privileges.

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Beginners guide to Packet sniffing

Hello, aspiring Ethical Hackers. In this blogpost, you will learn about packet sniffing. Data doesn’t get hacked when it is sitting on a computer or a hard disk. It also gets hacked when it is in transit between one system and another system over internet. For example, in 2008, the Heartland Payment Systems which is one of the world’s largest credit card payment processors was hacked by two Russian hackers. After gaining access, they placed sniffers within the Heartland system. Using these sniffers, they collected 130 million credit card credentials.

What is Packet Sniffing?

Packet sniffing is an act or method of monitoring, gathering or collecting data or information while it is in transit from one system to another system (usually from client to server). Since data or information is transferred over internet in the form of small network packets, it is known as Packet sniffing.

Types of Sniffing

Sniffing can be classified into two types. They are Passive sniffing and Active sniffing.

1. Passive Sniffing:

In this type of sniffing, we just observe or monitor the traffic going around the network. There is no need of injection of any additional traffic into the network. To do this, we should be able to view the traffic belonging to all the devices in the network. This is only possible when all the devices in the network are connected through a Network hub. In a network connected by a hub, all the devices can see the traffic sent to all other devices on the network.

2. Active Sniffing:

In this type of sniffing, additional traffic has to be injected into the network to begin sniffing. This type of sniffing is performed in network connected by a switch.

What is a Sniffer?

Packet sniffing can be performed using either software or hardware. The software or appliance used to perform sniffing is known as a sniffer.

Examples of software sniffers include Wireshark, Tcpdump, Windump, Ettercap, dsniff, Kismet, Driftnet and Network miner etc.

Examples of Sniffing attacks

1. Password Sniffing:

This is the simplest form of sniffing attack as in this type of sniffing, sniffers just collect the data in transit silently. Although, sniffers are looking to sniff on credentials. any data that is not encrypted before being transmitted between two devices can be sniffed on. For example, protocols like FTP, Telnet and HTTP etc. transmit all data including credentials in clear text. Learn more about password sniffing attack here.

2. DNS Cache Poisoning:

Also known as DNS poisoning or DNS spoofing, this attack involves poisoning the cache of a DNS server. A Domain Name Server (DNS) resolves host names to the IP addresses and vice versa. So, if a DNS cache is poisoned with malicious entries, any user trying to visit a genuine website may be redirected to a fake malicious website.

3. MAC Flooding:

In this type of sniffing attack, attacker sends a large amount of traffic to the network switch to fill the MAC address table using fake MAC addresses. When the MAC address table is full, the network switch behaves like a hub.

4. MAC Spoofing:

Also known as ARP spoofing or ARP poisoning, in this attack, the attacker tries to spoof the MAC address of another device like a switch. This results in all the devices on the networks thinking that attacker-controlled computer is the switch and start sending traffic to it.

5. TCP Session Hijacking:

In this sniffing technique, also known as Session Hijacking, attacker steals the user’s session ID and impersonates as that user.

6. JavaScript Card Sniffing:

In this type of sniffing attack, hackers take control of a website and make changes to the javascript by adding malicious lines of code to it. These changes are done to collect any valuable information, like credentials, credit card numbers and other information.

7. DHCP attacks:

In this attack, DHCP server is flooded by the attacker with fake DHCP requests to use all the allocated IP addresses for that network.

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CVE-2022-25636 : Linux Privilege Escalation

Hello aspiring Ethical Hackers. In this article you will learn about another Linux Privilege Escalation vulnerability tracked as CVE-2022-25636 and its exploitation. I am saying another because this vulnerability comes immediately after recently discovered Linux Dirty Pipe vulnerability.

CVE-2022-25636 is a vulnerability that affects the Linux Netfilter component. What is netfilter? It is an open source framework provided by the Linux kernel that allows various networking-related operations to be implemented in the form of customized handlers. Its functions include packet filtering, network address translation and port translation. All Linux Firewall utilities i.e Iptables, nftables, ufw etc use Netfilter in their operations.

Exploitation of this vulnerability can give attackers root privileges on the target system, allow them to escape containers and in worst case induce a kernel panic. This vulnerability affects Linux kernel versions 5.4 to 5.6.10. The target OS include Ubuntu, Debian, RedHat etc.

However, there’s no clarity on which kernel versions are actually vulnerable. In my testing, this failed to work on Ubuntu 21.10 kernel version 5.13.0-10 but worked every time on Ubuntu 21.10 with kernel version 5.13.0-30 (without giving any panic). Let’s have a look at how the exploitation worked for me.

To exploit this privilege escalation vulnerability, anybody needs to have access on the target system with Low User Privileges as shown below.

Once I have a shell on the target, I download the exploit from Github as shown below.

Next, I navigate into the CVE-2022-25636 directory and compile the exploit as shown below.

Then I executed the exploit as shown below.

cve-2022-25636

As readers can see, I successfully got a shell with root privileges.

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Dirty Pipe vulnerability for beginners

Hello aspiring Ethical Hackers. In this article, we will explain you about the Dirty Pipe vulnerability and how it can be exploited to get root privileges. Considered to be more prevalent than the Dirty Cow vulnerability and more simpler to exploit, the Dirty Pipe vulnerability affects Linux kernels since 5.8. To make it worse, this vulnerability affects even Android as its OS is based on Linux. Dubbed as CVE-2022-0847, this vulnerability is fixed in kernel versions 5.16.11, 5.15.25 and 5.10.102.

To understand the Dirty Pipe vulnerability, readers need to understand a few concepts in Linux.

Pipe : A pipe is a data channel that is used for uni-directional inter-process communication in Linux.

Memory Page : Whenever some data is written to a pipe, a page is allocated to it. A page is ring of a struct pipe buffer implemented by the Linux kernel. The first write to any pipe is allocated a page which is over 4 kB worth of data. If the latest data written to a pipe does not fill the page completely, the following data written will be appended to the same page instead of being allocated a new page.

For example, let’s say 2Kb of data is written to a pipe for which a page is allocated. When the subsequent 1KB of data is written to a pipe, this 1KB of data is appended to the same page instead of being allocated a new page. Anonymous Pipe Buffers work like this.

Page Cache : Memory pages are handled by kernel subsystem called page cache. Whenever any file is read or being written, the data is put into the page cache. This is done to avoid accessing disk for any subsequent reads and writes. This data in the page cache remains for some time until the kernel decides it needs that space for a better purpose. A page cache becomes “dirty” when the data inside the cache has altered from what is on the disk. This is where the name of the vulnerability comes from.

Pipe Flag : The status and permissions for the data in the pipe are specified by Pipe Flags. For DirtyPipe vulnerability, a flag named PIPE_BUF_FLAG_CAN_MERGE plays an important role by specifying that the data buffer inside the pipe can be merged.

System Calls : System Calls or syscalls are methods that can send requests to the kernel from the user space (the portion of memory containing unprivileged processes run by a user). System Call is the fundamental interface between an application and Linux Kernel.

Splice() : Splice is a syscall that was introduced since Linux 2.6.16 that can move data between pipes and file descriptors without user space (the portion of memory containing unprivileged processes run by a user) interaction.

Now, since you have been explained the basic concepts that make this vulnerability work, let’s get into the vulnerability itself.

Whenever any data is copied from a file into the pipe using splice() function, the kernel will first load the data into the page cache as already explained above. Then kernel will create a struct pipe_buffer inside the page cache. However unlike anonymous pipe buffers, any additional data written to the pipe must not be appended to such a page because the page is owned by the page cache, not by the pipe.

Since the page cache is run by kernel (high privileges), any user with low privileges can exploit this vulnerability to take an action requiring high privileges. Enough theory. Let’s get into practical exploitation. We are going to try this on Debian 11 with kernel 5.10.0.

I will try to get a root shell by exploiting this vulnerability. For this, I will download a exploit as shown below.

I compile the exploit which is a C script.

Then I execute the exploit as shown below. This will create a new user named “rootz” with root privileges.

dirty pipe

Once you get the message saying “It Worked”, the exploitation is successful. All I have to do is login as the new user (rootz) as shown below.

Voila, I have a root shell. The exploitation is successful.

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AntiVirus Evasion With Exocet

Hello aspiring Ethical Hackers. In this article, you will learn about AntiVirus Evasion with the help of a tool named Exocet. Exocet is a Crypter type malware dropper. A Crypter is a software that is used to make malware undetectable. It performs functions such as encrypting, obfuscating and manipulating the code of the malware to make it undetectable.

EXOCET is one such Crypter-type malware dropper that can be used to recycle easily detectable malware payloads. EXOCET achieves this by encrypting those malware files using AES-GCM (Galois/Counter Mode) and then create a dropper file for a majority of target architectures and platforms.

Written in Golang programming language, the steps involved in making malware undetectable by EXOCET are,

  1. It first takes malware that is easily detectable by Anti Virus engines as input.
  2. It then encrypts this easily detectable malware and produces it’s own Go file.
  3. This Go file can be cross-compiled to 99% of known architectures like Linux, Windows, Macs, Unix, Android and IPhone etc.
  4. Upon execution, the encrypted payload is written to the disk and immediately executed on the command line.

Let’s see how it works. First, we need to install Golang on Kali as Exocet is a Go program.

Once Golang is successfully installed, clone the repository of Exocet. It can be downloaded from here.

We need to install the EXOCET source files in golang. We can do this using the command shown below.

Exocet is successfully installed. Now, let’s test it. We create a reverse shell payload with Msfvenom first.

We copy this payload to our target system which is Windows 10. The Windows Defender easily detects it (obviously) and classifies it as malware.

This is expected. Next, We copy this easily detectable payload to the directory of Exocet.

Then we run the following command using Exocet. This will create a new golang file called outputmalware.go.

Then we run the following command to create a Windows 64 bit payload.

av evasion

Our result is the exocet_payload.exe. We start a Metasploit listener on the attacker system and copy the Exocet payload to the target.

This time the payload goes undetected as shown below.

This is how we perform AntiVirus Evasion with Exocet Tool.