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In Hacking the main focus is over gathering the information about victim or victim's machine. Which will help to find out which type of exploit will works according to the given circumstances. Gathering the network and host information means to find out by which network, the which victim's machine is connected and communicating over the network. Moreover, scanning is also performed for gathering information about open and closed ports. After that they'll able to find the vulnerabilities in the target system and try to get access to the system.

Types Of Scan

As a CEH you should know the scan types and uses:

SYN

SYN scan doesn't complete the TCP three way handshake that is why it is known as a half-open scan. An attacker send a SYN packet to the victim machine if SYN/ACK packet is received back to attacker, then it clarify that the port is listening due to the acknowledgment by the victim that it has completed the connection. While if the attacker is received the RST/ACK packet then it assumed that the port is closed or open.

XMAS

XMAS scan works only on target system that has the RFC 793 development of TCP/IP and it doesn't works against any version of windows.
XMAS scan send a packet with by setting up the FIN, URG and PSH flags of the TCP header. The function of this scan is if the port is active there will be no response but if the port is closed the target responds with a RST/ACK packet.

FIN

A FIN scan send a packet by setting up only the FIN flag of the TCP. This scan is similar to XMAS scan. FIN scan receives no response if the port is active while if the port is closed it receives the RST/ACK packet.

NULL

NULL scan is also similar to the XMAS scan. But the only difference is that it sends a packet without setting up the any flag of TCP header. NULL scan receives no response if the port is open but if the port is closed it receives the RST/ACK packet.

IDLE

It is just like spoofing an IP address by sending a SYN packet to the victim's machine to find out which services are available over the system. This scan is completed with the help of another system called as "Zombie" (that is not receiving or transmitting any information).

This story is about a bug generated by g++ and clang compilers (at least)
The condition_variables is a feature on the standard library of c++ (libstdc++), when its compiled statically a weird asm code is generated.

Any example on the link below will crash if its compiled statically:
https://en.cppreference.com/w/cpp/thread/condition_variable

In this case the condition_variable.wait() crashed, but this happens with other methods, a simple way to trigger it:

If this program is compiled dynamically the crash doesn't occur:

Looking the dissasembly there is a surprise created by the compiler:

Compilers:
g++ 9.2.1+20200130-2
clang++ v9

Both compilers are generating the "call 0x00"

If we check this call in a dynamic compiled:

The implementation of condition_variable in github:
https://github.com/gcc-mirror/gcc/blob/b7c9bd36eaacac42631b882dc67a6f0db94de21c/libstdc%2B%2B-v3/include/std/condition_variable

The compilers can't copile well this code in static, and same happens on other condition_variable methods.
I would say the _lock is being assembled improperly in static, is not exacly a null pointer derreference but the effects are the same, executing code at address 0x00 which on linux is a crash on most of cases.

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Create a vulnerable active directory that's allowing you to test most of active directory attacks in local lab.

Main Features

Randomize Attacks
Full Coverage of the mentioned attacks
you need run the script in DC with Active Directory installed
Some of attacks require client workstation

Supported Attacks

Abusing ACLs/ACEs
Kerberoasting
AS-REP Roasting
Abuse DnsAdmins
Password in AD User comment
Password Spraying
DCSync
Silver Ticket
Golden Ticket
Pass-the-Hash
Pass-the-Ticket
SMB Signing Disabled

Example

# if you didn't install Active Directory yet , you can try 
Install-ADDSForest -CreateDnsDelegation:$false -DatabasePath "C:\\Windows\\NTDS" -DomainMode "7" -DomainName "cs.org" -DomainNetbiosName "cs" -ForestMode "7" -InstallDns:$true -LogPath "C:\\Windows\\NTDS" -NoRebootOnCompletion:$false -SysvolPath "C:\\Windows\\SYSVOL" -Force:$true
# if you already installed Active Directory, just run the script !
IEX((new-object net.webclient).downloadstring("https://raw.githubusercontent.com/wazehell/vulnerable-AD/master/vulnad.ps1"));
Invoke-VulnAD -UsersLimit 100 -DomainName "cs.org"

TODO

Add More realistic scenarios
Click close issue button on github

Download vulnerable-AD

via KitPloit

On Pins and Needles

Sunday, August 30, 2020

Webkiller Tool | Information Gathering | Github

CEH: Gathering Network And Host Information, Types Of Scan

Types Of Scan

SYN

XMAS

FIN

NULL

IDLE

Related posts

C++ Std::Condition_Variable Null Pointer Derreference

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Saturday, August 29, 2020

Vulnerable-AD - Create A Vulnerable Active Directory That'S Allowing You To Test Most Of Active Directory Attacks In Local Lab

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