Haunted by a Living Ghost: Skeleton Key: Cómo Poner Una Clave Maestra En El Domain Controller En Windows Server 2016 Y Controlarlo Una Vez Hackeado

Who Are The Living Ghosts?

A living ghost is a 'disgusting' but perhaps accurate term applied to a person who has come to the UK to claim asylum and been unsuccessful http://www.church-poverty.org.uk/campaigns/li..

Once this happens, and if his/her appeal fails then there is an expectation that the individual will return voluntarily to his/her country of origin, and if this does not happen he or she will lose all access to public support i.e. no rights to accommodation, no rights to seek employment, no rights to claim government benefits, no rights to social care and the most basic rights to medical care.

In this situation, a person becomes virtually invisible hence the term 'Living Ghost'. Nobody really sees the living ghost except when crime is committed or when the housing shortage hits an all time high. This is the time when the living ghost is most noticed.

I have always found this to be particularly odd as the living ghost has no entitlement to housing and if he/she has no access to employment or benefits how is he/she meant to survive?

I have to say however, that the people I know in this situation have never been involved with the criminal justice system, in fact they are terrified of the police. In their countries, if you get arrested, you are usually out cold by the time you reach the patrol car or dead.

Now you might wonder how the hell a person in this situation actually manages to survive? How do they eat? Where do they sleep? Do they sleep? What happens if they become ill? and please don't forget that many people seeking asylum in the UK have often fled their own countries in fear for their lives, they may have been detained & tortured, raped or lost family members as a result of war, the list is endless.

It shouldn't be so difficult to survive though should it? I mean, they take our jobs (err sorry! no permission to work!) our houses (oops! no permission to access housing) Oh yes!! lets not forget our women because we really have no independent thought processes do we?

Taking into account the atrocities that some of these people have endured in their lives, is it not suprising that people do not return 'voluntarily'?

Now in many cases, the Home Office http://www.ukba.homeoffice.gov.uk/ do not deport people back home, why? because their countries are known to be unsafe, it's just their accounts of what happened that weren't believed.
So when this happens they are left destitute and are living on our streets, in our democratic country in the 21st century how disgusting is that?

Welcome To The United Kingdom!

STOP EXECUTIONS IN IRAN!

According to the United Nations Convention Against Torture 1984, Article I, the term "torture" means any act by which severe pain or suffering, whether physical or mental, is intentionally inflicted on a person for such purposes as obtaining from him or a third person information or a confession, punishing him for an act he or a third person has committed or is suspected of having committed, or intimidating or coercing him or a third person, or for any reason based on discrimination of any kind, when such pain or suffering is inflicted by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity. It does not include pain or suffering arising only from, inherent in or incidental to lawful sanctions.Iran is not signatory of Convention Against Torture but it doesn't give Iranian government any right to torture Iranians.

Surely Things Aren't Really That Bad Are They? Come on, What's for Tea?

Now before you sit down and eat, I'd like you to try a little exercise, anyone can join in and it will only take about 10 minutes maximum. It doesn't matter who you are, whether you are a council worker, a politician, the Prime Minister, homeless, destitute it really does not matter.
Just close your eyes for a moment and imagine this.......

You live in a beautiful country, lets say Iran to keep it simple. Things are hard but your country is amazing, beautiful buildings, warmth, the smell of home cooking and incense wafting by as you relax after a day's hard work. You have always struggled, never really fitted in because your father is Iranian and your Mother Kurdish but nevertheless that's part of life and there are mixed race people everywhere.
Suddenly you are jolted from your relaxation by banging on your door so you rush to see what the problem is.
It must have only taken a few seconds to reach the door but when you get there you see your elderly father being taken by military police handcuffed with a gun to his head.
You stare in horror and then being the eldest son you need to make sure your mum & sister are ok.
In your mum's room you see her crying on the bed and just as you are walking over to her your sister screams so you rush to her room but one soldier is still there so you can't do a thing except witness her rape and torture that seems to last a lifetime. Your mum knows whats happened and she is praying that she will die. Imagine that!
Imagine this is the 5th, 6th 7th or 8th time this has happened?
Your father, well you never saw him again after the first time, your sister could face execution for having sex before marriage and now who will marry her anyway?
Your Mother well she still wants to die but can't quite get there & you! are meant to protect them but you know the interrogators will be back for you because your're half Kurdish and you support independence for Kurdish people and they really don't like that.
Imagine that!! so you flee to protect your own life and also you feel that it may be easier on your family if you aren't there.
You don't know where you will end up when you smuggle yourself onto lorries, boats e.t.c or even if you will get to the other end alive but you do it....you are amazing imagine that!

This exercise wasn't made up, it was based upon real life history. A close friend of mine who I will call S experienced this and more on a regular basis. S is a man who was detained, raped and tortured systematically by the Iranian regime. Other examples include.......

Thousands face mass eviction from homes and market stalls in Zimbabwe
Up to 200 people from an informal settlement in the Harare suburb of Gunhill in Zimbabwe face being forcibly evicted without being given adequate notice or any consultation or due process. Thousands of vendors across Harare also face forcible removal from their market stalls. The majority of those to be affected are poor women whose principal source of livelihood is selling fruits, vegetables and other wares at market stalls like Mbare Musika and Mupedzanhamo in Harare.The Deputy Mayor of the Harare City Council stated in July 2009 that the city authorities are considering evicting people from "illegal settlements and market places to restore order." He claimed that the targeted people pose a health hazard and violate the city's by-laws.
www.hrw.org/ (Human Rights Watch 2009)

Iranian girl prisoners systematically raped before execution
The Iranian practice of raping girl prisoners before execution has been reported previously, but perhaps never with such clear documentation. "Progressives" who support this regime should keep it in mind. It is unlikely that there will be any investigation by the UN or a human rights group.

Ami Isseroff

'I wed Iranian girls before execution'
Jul. 19, 2009SABINA AMIDI, Special to The Jerusalem Post , THE JERUSALEM POST
In a shocking and unprecedented interview, directly exposing the inhumanity of Supreme Leader Ali Khamenei's religious regime in Iran, a serving member of the paramilitary Basiji militia has told this reporter of his role in suppressing opposition street protests in recent weeks.
He has also detailed aspects of his earlier service in the force, including his enforced participation in the rape of young Iranian girls prior to their execution.
He said he had been a highly regarded member of the force, and had so "impressed my superiors" that, at 18, "I was given the 'honor' to temporarily marry young girls before they were sentenced to death."
In the Islamic Republic it is illegal to execute a young woman, regardless of her crime, if she is a virgin, he explained. Therefore a "wedding" ceremony is conducted the night before the execution: The young girl is forced to have sexual intercourse with a prison guard - essentially raped by her "husband."
"I regret that, even though the marriages were legal," he said.
Why the regret, if the marriages were "legal?"
"Because," he went on, "I could tell that the girls were more afraid of their 'wedding' night than of the execution that awaited them in the morning. And they would always fight back, so we would have to put sleeping pills in their food. By morning the girls would have an empty expression; it seemed like they were ready or wanted to die.
"I remember hearing them cry and scream after [the rape] was over," he said. "I will never forget how this one girl clawed at her own face and neck with her finger nails afterwards. She had deep scratches all over her."

Still hungry?

Oh Mr. Brown! (Gordon) you are an exception enjoy your tea!

(THIS IS THE UNITED KINGDOM)

The United Kingdom is a Country of Democracy, Equality and Values the Protection of Human Rights.

So you have arrived in the United Kingdom tired, hungry, traumatised and dehydrated but nevertheless grateful to be in a country where you know you will not be executed..(there's a good start).

Despite your frail state however you manage with the help of an interpreter to complete a lengthy document stating your claim for asylum and why you were forced to flee your beautiful country with the wonderful history and the smell of home cooking e.t.c. for a country you know absolutely nothing about....You are amazing!

Asylum is given under the 1951 United Nations Convention Relating to the Status of Refugees http://www.asylumrights.org.uk/convention.htm.

To be recognised as a refugee, you must have left your country and be unable to go back because you have a well-founded fear of persecution because of your:
.race;
.religion;
.nationality;
.political opinion; or
.membership of a particular social group.

In 2007, 19 out of every 100 people who applied for asylum were recognised as refugees and given asylum.

Eventually you are offered accommodation with the support of NASS National Asylum Support Service (NASS) just until a decision is made about whether you will be granted leave to remain in the United Kingdom. You are also provided with vouchers so that you can eat.
www.asylumsupport.info/nass.htm

Things seem to be a little easier now and you can relax and recover from your ordeal in the knowledge that you will be safe but you can't look for a job to support yourself or access a house independently not yet! not until you become a British Citizen so you'll just have to hope for the best for now and wait until you get your UK leave to remain.

This means that it will be almost impossible to learn English Language at the moment because you don't really have the chance to mix in with British people as most of them congregate in places like 'Workplaces' or 'Housing Communities' all the places you can't go.

I guess you could go to social places like clubs or pubs but you don't have any money to do that and they don't accept vouchers sorry! but I guess you have freedom of choice don't you?

Beyond What is Visible

You were once a stranger to me but now I know you,
Not all of you, that could never be
Always a part of you that no one will ever see, not even me.

Once a stranger with beautiful brown eyes, the most beautiful eyes I have ever seen,
Eyes that felt nothing, no emotion nothing in between, this life and beyond.

We were once strangers but then we touched,
Not in the way some might think, not too much.
The touch we shared was deep and true,
Not physical but you did touch me and I did touch you.

You were once a stranger to me but now I know you,
Not all of you, that could never be.
Sometimes there's a moment when your eyes melt me,
So warm and compassionate, oh such a change in time, or is it?
Maybe I was blind.

We dont have words but thats fine,
I don't speak your language and you don't speak mine
But when you touched me I understood what you needed to say, it just needed time.

The Decision.........Dont worry!! Help is at hand. This is the United Kingdom.

So today is the day! the letter has arrived and with anticipation you open it.
You don't understand.............
You told the truth, explained why you had to flee your country, about the rape the torture why have they refused your application?
Why?
Quickly you must try and lodge an appeal against this decision.
The Home Office have stated that certain things are untrue or overstated but you know you told the truth.

You admit and acknowledge that when you lodged your claim, you were traumatised, tired, hungry and dehydrated and had travelled for thousands of miles in appalling conditions but you told the truth.
So you lodge your appeal and this fails too so what now?

Another letter arrives... you breath a sigh of relief as this could be to say that they made a mistake, they were wrong but no, its from NASS to say that in 28 days you must leave your home and return voluntarily to your country as you are now not permitted to remain in the UK. In 28 days time your vouchers will cease also.

So far you have managed alone with your memories of what happened to you and your family, tormented and unable to sleep you have paced the floor, even turned to alcohol which in your country is prohibited but you coped now its different. Who can you turn to? where can you get help when you don't even speak English?
Maybe the nurse in the hospital will understand as you wake up with both your wrists bandaged.

Relax! This is the United Kingdom there is always a way forward.

In the UK there is something called Section 4 support

Section 4 support

Applying for support

This page explains how you may qualify for short-term support if your application for asylum was unsuccessful, you are unable to return to the country you came from and would otherwise be homeless or without the money to buy food (we call this 'destitute').
If your asylum application has been rejected, you must return to your country of origin as soon as possible. However, you may be able to receive short-term support while you are waiting to return to your country. This is known as section 4 support because it is given under the terms of section 4 of the Immigration and Asylum Act 1999.
There are strict requirements you must meet in order to qualify for section 4 support. You must be destitute and satisfy one of the following requirements:
you are taking all reasonable steps to leave the United Kingdom or placing yourself in a position where you can do so;
you are unable to leave the United Kingdom because of a physical barrier to travel or for some other medical reason;
you are unable to leave the United Kingdom because the UK Border Agency believes there is no safe route available;
you have either applied for a judicial review of your asylum application in Scotland or applied for a judicial review of your asylum application in England, Wales or Northern Ireland and been given permission to proceed with it; or
accommodation is necessary to prevent a breach of your rights, within the meaning of the Human Rights Act 1998.

http://www.ukba.homeoffice.gov.uk/asylum/support/apply/section4/

So What is Section 4 all about?

Now Section 4 of The Asylum and Immigration Act 1999 is a magical piece of legislation put in place by the Home Office to help you so please trust them and do not listen to anyone who tells you otherwise.

Yes thats right! The Home Office were the people who looked at your asylum claim and refused it.

Lets take a closer look at Section 4 and what you must do to get it....

1- You must be willing to leave the UK and you must be putting yourself in a position to do so.

Oh but wait! you came to the UK fleeing for your life so this wont work.

2-You cannot leave the UK because you are unable to travel due to physical barriers.

Hmmm at the moment you are not registered as having these kinds of problems and even if you had, who would be aware of it? You have no access to anything and in any case you can't speak English.

3- you are unable to leave the United Kingdom because the UK Border Agency believes there is no safe route available;

Well your asylum claim was refused so the Home Office obviously believe it is safe.

4-
you have either applied for a judicial review of your asylum application in Scotland or applied for a judicial review of your asylum application in England, Wales or Northern Ireland and been given permission to proceed

Your asylum claim and appeal was refused (Not doing too well here)

5-
accommodation is necessary to prevent a breach of your rights, within the meaning of the Human Rights Act 1998.

Damn!! They just took your accommodation.

On a positive note, your local authority (The city where you live) know about this so they should help shouldn't they?
Let's hear what they have to say,and what they are planning to do about it..............

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MCC Manchester News
News, events and activities in the life of the Metropolitan Community Church, Manchester (UK).
May 30, 2009
Support for refused asylum seekersPosted by Steve Gray under Social action Tags: Amnesty International, Asylum seekers, Destitution, Refused asylum claims, Still Human Still Here Campaign Leave a Comment

Refused asylum seekers left destitute in the UK
Background information

No doubt you will have heard or read reports about how the UK is meant to be a “soft touch” for asylum seekers. Yet, in reality, the level of support provided to asylum seekers is far lower than that of income support and is usually withdrawn altogether if a claim is refused.

Many refused asylum seekers are, in fact, unable to return to their home countries due to the risks they would face because of, for example, armed conflicts, generalised violence and repressive regimes. As a result, many refused asylum seekers from countries where such problems are rife (including Zimbabwe, Iran, Iraq, Sudan, Afghanistan, Somalia, the Democratic Republic of Congo and Eritrea) are being forced into destitution, as they are not permitted to work here.

To make matters worse, it appears as though this could be part of a deliberate strategy on the part of the UK Government. Certainly, this is the view of the Joint Committee on Human Rights, which recently reviewed the treatment of asylum seekers in the UK and reached the following conclusion:

“We have been persuaded by the evidence that the Government has indeed been practising a deliberate policy of destitution of this highly vulnerable group.

We believe that the deliberate use of inhumane treatment is unacceptable. We have seen instances in all cases where the Government’s treatment of asylum seekers and refused asylum seekers falls below the requirements of the common law of humanity and of international human rights law”.
In light of this, we are calling on you to support the Still Human Still Here Campaign, which is fully endorsed by Amnesty International and many other reputable organisations (http://stillhumanstillhere.wordpress.com/).

The Still Human Still Here Campaign is dedicated to highlighting the plight of tens of thousands of refused asylum seekers who are destitute in the UK.

Supporters of the campaign believe that the denial of any means of subsistence to refused asylum seekers as a matter of government policy is both inhumane and ineffective.
Its supporters are calling on the Government to:
End the threat and use of destitution as a tool of Government policy against refused asylum seekers

Continue financial support and accommodation to refused asylum seekers as provided during the asylum process and grant permission to work until such a time as they have left the UK or have been granted leave to remain

Continue to provide full access to health care and education throughout the same period

What can I do?

We are asking you to write to your local MP in order to highlight the issue and ask for his or her support. Please feel free to use the model letter below (preferably adapting it, where possible) for this purpose. If you don’t know who your

MP is, you can find out at http://www.theyworkforyou.com/.

Then, all you need to do is send your letter (addressed to your own MP) to:
House of CommonsLondonSW1 0AA
If you receive a reply from your MP, please send a copy to The Human Rights Action Centre, 17-25 New Inn Yard, London, EC2A 3EA

Well, they have been persuaded so theres a good thing, but it looks like they are going to do absolutely nothing!

Please Don't Be The Next Living Ghost

The inspiration for this blog has been given to me by some truly amazing people who I have been fortunate to meet along life's journey. Unfortunately, although it would be an honour to use their full titles I am only able to identify them by initials.
Some of the mentioned people have fled their countries in fear of their lives, and some sadly did not make it.

I would like to take this opportunity to thank these people from the bottom of my heart for allowing me to be a part of their journey and for being courageous enough to come forward with their stories.

I hope that after visiting my blog you will share some of your own experiences and be proactive in writing letters and doing whatever it takes to make changes to the current asylum laws.

This can be done, it just takes time and determination and most of all a willingness to stand in unity.

S.M -A courageous and amazing man of Kurdish-Iranian origin. Having experienced torture & detention for political reasons he fled to the UK in fear for his life. This man has diagnosed Post Traumatic Stress Disorder and needs close monitoring due to five previous and serious suicide attempts. Initial asylum claim failed and now in the process of appeal. If returned to Iran he faces definite execution.
This man lives in Manchester England.

S.G.T- A courageous and amazing man of Kurdish Iranian origin, having fled his country for political reasons he still awaiting the outcome of his asylum claim to remain in the UK. A member of the PKK (Kurdish Independence Party) he will definitely face execution by hanging if returned.
This man lives in Manchester England.

S.H - A courageous and amazing Iranian man who fled Iran following his relationship with a girl of Jewish origin. The Basij police cut her throat in front of him and beat him so badly that he sustained a 7" scar on his head from a machete type blade (His father was one of Basij). In the UK he became a 'living ghost' and eventually returned to Iran as he could take no more pain and hopelessness from his destitute situation. He was subsequently executed by hanging, accused of espionage.

A.A -An amazing and couragious man who fled his home country of Iran because of political reasons. He is currently destitute on the streets of Manchester UK having failed his asylum application and appeal. He is now a living ghost.

F.A -Also a courageous and amazing man from Iran who was picked up and detained following a protest in the UK against the Ahmadinejad regime in his home country in which his family are stuck. This man faces deportation back to Iran where he is likely to be executed as an opposer of the Ahmadinejad government.
This man lives in Manchester England

A.R.Z -A courageous and amazing man from Afghanistan currently in the UK.
This man has his leave to remain in the United Kingdom but is so mentally affected by the atrocities and torture he endured in his country, he is unable to ever feel safe. He is dependent upon opium and living in Manchester England

M.M- A courageous and amazing young man of Iranian origin. Having fled his country because of sexuality reasons he came to the UK.
Homosexuality in Iran is punishable by the death penalty and his partner was hung at the age of just 23yrs.
This man failed in his application for asylum and in his appeal against the decision. He is now a living ghost in Manchester England.

M. An amazing and courageous young man from Eritrea who fled to the UK in fear for his life after all his family, mother, father, 2 brothers and his baby sister were slaughtered in front of his eyes by militia.
He escaped by hiding in a cupboard. He is awaiting the outcome of his appeal for asylum in the UK. He currently resides in accommodation provided by NASS due to his young age.

A.S An amazing and courageous man from Iran who has been deeply affected by the aftermath of the Iran Iraq war in which he served as a soldier. This man has serious mental health problems and the need for counselling but cannot access it having no access to support after his asylum claim and appeal were refused in the UK. Recently he stitched his own mouth and went on hunger strike just so someone would listen. He lives in Manchester.

MB, An amazing and Courageous Angolan man who was detained in Yarl's Wood with his 13-year-old son, was found hanged in a stairwell on the morning of his 35th birthday.
M's last words to his son were 'be brave, work hard, do well at school'

EN, An amazing and Courageous 26-year-old Zimbabwean man who was found drowned after his asylum claim and appeal to remain in the UK had failed.

HN-An amazing and Courageous man from Iran who was found with a gunshot wound two weeks after his asylum claim was refused.
H, was homosexual and fled Iran in March 2000 after being imprisoned for three months for his sexuality and sought sanctuary in the UK. He feared being executed if he was returned to Iran - where homosexuality is a 'crime' punishable by death.

Please Check out the following links and make a difference: Additionally, please contact me at:
morgana.1@hotmail.co.uk

http://stllhumanstillhere.wordpress.com/
http://www.church-poverty.org.uk/campaigns/li..
http://www.irr.org.uk/2005/september/ha000021.html
http://www.redcross.org.uk/.
http://www.torturecare.org.uk./
http://www.refugee-action.org.uk/manchester.
http://www.sareli.org.uk./
http://www.samaritans.org./
http://www.woodstreetmission.org.uk./

http://www.qva.org.uk/

http://www.immigrationboards.com

Tuesday, 19 May 2020

Skeleton Key: Cómo Poner Una Clave Maestra En El Domain Controller En Windows Server 2016 Y Controlarlo Una Vez Hackeado

La técnica que hoy se muestra en el artículo no es nueva, pero podemos decir que para muchos será desconocida. Este técnica tiene grandes frases cómo: "Todas las puertas de tu Active Directory quedan abiertas con la técnica Skeleton Key". Al principio el tema puede parecer complejo, pero viendo en qué se basa, la idea es sencilla. Podemos hablar de que Skeleton Key te da persistencia, pero realmente es parcial, ya que en el momento que se reinicie el DC o Domain Controller se acabó la persistencia. El tema es que un DC no se reinicia todos los días, por lo que podemos hablar de cierto grado de persistencia.

Figura 1: Skeleton Key: Cómo poner una clave maestra en el Domain
Controller en Windows Server 2016 y controlarlo una vez hackeado

Antes de hablar en qué consiste esta técnica y ponerla a prueba vamos a hablar de que hay varios métodos para comprometes cuentas de Active Directory con el objetivo de escalar privilegios y crear persistencia. ¿De dónde viene esta técnica? Fue vista en malware orientado a dominios de Active Directory, el cual permitía el secuestro de cualquier cuenta. ¿Cómo? Esta pieza de código se inyectaba en el proceso lsass.exe y creaba lo que llamaremos una contraseña maestra, la cual funcionaría para cualquier cuenta del dominio. La idea mola.

Figura 2: Libro Windows Server 2016: Administración, Seguridad y Operaciones

Lo curioso de la técnica es que las contraseñas existentes también siguen funcionando, por lo que es complejo saber si el ataque se ha llevado a cabo. Más adelante hablaremos de la mitigación o el cómo darse cuenta o tener indicios de que Skeleton Key ha sido ejecutada en nuestro DC. Para entender bien esta técnica, cuantos más conocimientos tengas de Windows Server 2016:Administración, Seguridad y Operaciones, mejor que mejor, así que te recomiendo la lectura de este libro de 0xWord que explica muchos de los conceptos que vamos a utilizar hoy. Y si tienes tiempo, puedes hacerte el VBook de Windows Server 2016.

Requisitos antes de comenzar

Los requisitos del ataque Skeleton Key son los siguientes:

- Solo es aplicable a los Domain Controller.

- El pentester tiene que ser admin del dominio.

- Cuando la máquina reinicia, el DC eliminará el Skeleton Key y deberá ser desplegado de nuevo si se quiere optar a tener los privilegios que se consiguen con Skeleton Key.

¿En qué consiste? Este ataque se aplica sobre dos métodos de autenticación: NTLM y Kerberos. Cuando se realiza la autenticación NTLM se inyectará el hash NTLM de la contraseña maestra, si lo hacemos con Mimikatz, ésta será "mimikatz". El hash se inyecta en el proceso lsass.exe y no se comprobará contra la SAM. De esta forma, cuando hagamos login con el usuario X y la contraseña correspondiente al hash que hemos inyectado, se logrará autenticar en el controlador de dominio.

Figura 3: Máxima Seguridad en Windows Gold Edition

El cifrado de Kerberos sufrirá un "downgrade" a un algoritmo que no soporte "salt": RCA_HMAC_MD5 y el hash que se recupera del AD es reemplazado por el hash generado con la técnica Skeleton Key. El hash que corresponde con la contraseña maestra es validado en el lado del servidor, por lo que se consigue una autenticación exitosa, tanto en NTLM como en Kerberos.

Skeleton Key 'on fire'

Antes de empezar a jugar vamos a proponer un escenario sencillo, pero real. A continuación se muestra:

- Metasploit (en cualquier máquina o contenedor de Docker que tengáis a mano). Intentaremos que sean últimas versiones. Yo he realizado un msfupdate antes de ejecutarlo.

- Máquina Windows Server 2016 con dominio de pruebas HC (de mi querido hackersClub).

- Máquina con un Windows cliente para conectarse con la clave maestra, una vez hecho el proceso.

Para entrar en el Domain Controller vamos a simular el acceso con el módulo web_delivery de Metasploit. Tras comprometer el Domain Controller habría que lograr escalar privilegios en el sistema, ya que sin ello no se podría hacer uso de Skeleton Key. En la siguiente imagen se puede visualizar la configuración del módulo web_delivery de Metasploit con el uso de un Meterpreter inverso. Ese código Powershell es el que utilizaremos para simular la intrusión.

Figura 4: Ataque con módulo web_delivery

Una de las cosas que me ha sorprendido de las últimas versiones y las modificaciones que ha ido sufriendo el código Powershell que se genera con Metasploit es que primero envía un código de bypass de AMSI y, posteriormente, se ejecuta el resto del payload.

Figura 5: Pentesting con Powershell 2ª Edición

Es decir, primero se deshabilita AMSI en el proceso de Powershell y luego se ejecuta el resto del script que proporcionará un Meterpreter en memoria. Ya hemos comentado en el blog que esto, hoy en día es fundamental, ya que AMSI puede detectaros un gran número de herramientas, entre las que se encuentra nuestra querida iBombshell: La estrategia es, primero quito AMSI, luego ejecuto herramienta.

Figura 6: Bypass de AMSI y ejecución de payload

Tras obtener la sesión de Meterpreter en Windows Server 2016, vamos a mostrar algunos detalles importantes.

Figura 7: Información del sistema contrtolado

Como se puede la máquina se llama HC-SERVER, la arquitectura es de 64 bits, tanto en máquina como el Meterpreter, y vemos que tenemos privilegios para impersonar a SYSTEM, por lo que entonces lo hacemos. Aquí ya hemos simulado esa escalada de privilegios, tendríamos el control del Domain Controller. Y desde aquí podríamos planear todos los ataques del Hacking Windows que quisiéramos.

Figura 8: Libro de Hacking Windows

Ahora, se puede hacer de varias formas. Podemos generar un Mimikatz y subirlo, pero debemos tener en cuenta que no nos lo "caze" el AV. Podemos cargar el módulo Kiwi que tiene Meterpreter y ejecutar la sentencia de Mimikatz sobre Skeleton Key. Para ello, haremos uso de "load kiwi" y cargamos la extensión. Es importante que el payload sea de 64 bits, ya que aquí podemos encontrarnos un punto de fallo. Por otro lado, la sentencia a ejecutar para cargar Skeleton Key es: "kiwi_cmd misc::skeleton".

Figura 9: Cargando kiwi

Como se puede ver, todo ha ido bien y tenemos el "patch" listo. Ahora, vamos a ir a la máquina cliente, la cual puede ser nuestra u otra máquina que se haya comprometido en el pentesting. Antes de nada, hay que indicar que con la herramienta Mimikatz, desde su propia consola, hay que ejecutar lo siguiente:

- Privilege::debug

- Misc::skeleton

Con estas dos instrucciones tendríamos la Master Key ya en memoria y todo preparado para que desde el equipo cliente que sea, se pueda acceder a los recursos del DC.

Figura 10: mimikatz

Hay que fijarse en la contraseña utilizada "mimikatz". El usuario va con el dominio explícito y, como se puede ver, funciona. Para ver un poco más en detalle, deshacemos la instrucción anterior y comenzamos de nuevo.

Figura 11: Autenticación remota con password "mmikatz"

Ejecutando "dir \\hc-server\c$" vemos que no se puede acceder, pero en cuanto hacemos uso de net use para autenticarnos por SMB y poder utilizar un recurso remoto con la contraseña "mimikatz" se logra el acceso, tal y como se puede ver en la imagen.

Mitigación

En muchas ocasiones nos importa saber cómo se protege uno o cómo puede mitigarse el ataque. El uso de la técnica genera algunos eventos en el sistema que pueden ser buscados:

- ID 7045

- ID 4673 (En este "Audit Privilege Use" debe estar habilitado)

- ID 4611 ("Audit Privilege Use" debe estar habilitado)

En Powershell se puede ejecutar:

Get-WinEvent -FilterHashtable @{Logname='System';ID=7045} | ?{$_.message -like "Kernel Mode Driver"}

Ó si queremos buscar solo mimidrv:

Get-WinEvent -FilterHashtable @{Logname='System';ID=7045} | ?{$.message -like "Kernel Mode Driver" -and $.message -like "mimidrv"}

Si lsass.exe se ha ejecutado en modo proceso protegido o "protected process", fozará a un atacante o pentester a cargar "kernel mode drive". Se puede verificar lsass:

New-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Control\Lsa -Name RunAsPPL -Value 1 -Verbose

Verificar después del reinicio:

Get-WinEvent -FilterHashtable @{Logname='System';ID=12} | ?{$_.message -like "protected process"}

Tenéis más información sobre lo que se puede comprobar en este genial artículo sobre Skeleton Key y su mitigación.

Saludos,

Autor: Pablo González Pérez (@pablogonzalezpe), escritor de los libros "Metasploit para Pentesters", "Hacking con Metasploit: Advanced Pentesting" "Hacking Windows", "Ethical Hacking", "Got Root", "Pentesting con Powershell" y de "Empire: Hacking Avanzado en el Red Team", Microsoft MVP en Seguridad y Security Researcher en el equipo de "Ideas Locas" de la unidad CDCO de Telefónica. Para consultas puedes usar el Buzón Público para contactar con Pablo González