Tag Archives: WannaCry

An endless stream of SMB vulnerabilities …

11 June 2020

SMBleed, SMBLost, and SMBGhost/CoronaBlue are the vulnerabilities detected in the Microsoft SMB V3 protocol this year.

Critical SMB Vulnerabilities

Critical SMB Protocol Vulnerabilities

SMBleed/SMBGhost can be used to compromise a company network by attacking a system in the DMZ with port 445 open to the internet. Fortunately, SMBleed and SMBGhost impact only the latest Windows 10 versions. The number of Windows 10 systems directly accessible from the internet is still small.

Vulnerable Windows 10 1909 Pro Systems

Vulnerable Windows 10 1909 Pro Systems

Like EternalBlue, SMBLost impacts all Windows versions but is less critical because authentication (PR:L) is required.

The good news is that patches were available at the time the vulnerabilities were published. But it takes some weeks to implement them. During this time companies remain vulnerable against cyber-attacks.

Vulnerability management / priority patching is the standard approach to this kind of vulnerabilities. IT staff is kept busy, IT security solution and service providers make a good bargain, but the company’s resilience against cyber-attacks stays low. Companies can only hope that also the next SMB vulnerability is disclosed after a patch is available.

From an entrepreneurial point of view the obvious solution is to remove such systems from the internet. A risk assessment is imperative to evaluate the potential loss of sales and the costs of recovering from a cyber-attack. If the recovery costs exceed the potential loss of sales the system should be removed. This will slightly reduce IT costs but increase the resilience against such kind of cyber-attacks.

It is high time to evaluate IT[-security solutions] from an entrepreneurial point of view, in terms of Loss of Sales and Loss of EBIT.

Have a great weekend.

How to get the best ROI for investments in cyber security?

28 September 2019

During a workshop this week we had a discussion on risk management and investment in cyber security. Risk is the product of likelihood of occurrence (LoO) and severity of impact (SoI). So, to reduce the risk we can either try to reduce the SoI, or the LoO, or both.

We do risk management because we have limited resources. The big question is always: Where shall I spent my resources?  Or, where can I gain the best ROI? Shall I reduce the likelihood of occurrence or the severity of the impact? Or both?

The Cyber Kill Chain is a great model to study this.

Cyber Kill Chain - Risk Management - Cost

Cyber Kill Chain – Risk Management – Cost

We can reduce the likelihood of occurrence starting during the delivery phase up to the command & control phase. Once the attacker crosses the red line the LoO is 100 %.

The severity of impact can be reduced starting at the midst / end of the exploitation phase. WannaCry, for example, started the encryption immediately during installation of the malware and contacted in parallel its command & control server. Once the attacker crosses the red line, the impact and thus the costs for recovery are high.

The big problem with reducing the likelihood of occurrence is that we have in the best case only some seconds to minutes until the attacker crosses the red line. For efficient use of this time we need to invest in preventive or proactive means.

Cyber security awareness training, for example, is a very efficient preventive measure to reduce the LoO during the delivery and exploitation phase, because the exploitation of about 35% (Data NIST NVD, CVSS V3, UI:R) of vulnerabilities published in 2018 requires user interaction. Priority patching is another preventive measure with can stop an attacker early.

Backup and emergency recovery are great means to reduce the severity of impact. But the latest attack on Norsk Hydro makes clear that, even with the best crisis management, the recovery of some thousand systems from scratch takes some time.

When used in context with the existing security controls, the Cyber Kill Chain provides support in setting priorities in cyber security investment. The Mitre ATT@CK framework, which is based on the Cyber Kill Chain, brings the required methodology in the planning process. Give it a try.

Have a great weekend.

Critical Wormable Vulnerability CVE-2019-0708 patched. Is the world a safer place now?

19 May 2019

Microsoft released (1) a patch for the critical Remote Code Execution vulnerability CVE-2019-0708 (2) in Remote Desktop Services on May 14th, 2019. The vulnerability is wormable. A malware that exploits the vulnerability can spread from vulnerable computer to vulnerable computer in a way WannaCry did in 2017. Fortunately, only Windows XP, Windows 2003 Server, Windows 7 and Windows 2008 Server are impacted.

How big is the problem?

A Shodan search shows that about 30% of the Windows 2008 server systems directly connected to the internet are impacted. The Windows 2003 problem is much larger although Microsoft stopped the extended support for this version in July 2015.

Table 1: CVE-2019-0708 Impacted Systems. Source: Shodan. Data generated: 5/19/2019 7:30 pm

How to mitigate?

Since CVE-2019-0708 is a remote code execution vulnerability patches or other mitigating measures should be applied directly.

Microsoft provided patches with the May 2019 patch set, even for Windows 2003 Server and Windows XP, to prevent similar effects to that of WannaCry on the global economy. As an immediate step, Microsoft recommends deactivating RDP access to the impacted systems.

Is the world a safer place now?

Far from it. A brief analysis shows that many of the impacted systems provide applications based on a WAMP technology stack (Windows, Apache, MySQL, PHP). And in many cases remote code execution vulnerabilities in Apache or PHP are not patched. With this, the overall security level remains as bad as before Microsoft released the patches.

Without vulnerability and application life cycle management such problems cannot be solved. Apache, MySQL and PHP can be operated on top of an outdated Windows OS, but critical vulnerabilities in these components must be patched directly to avoid a large financial impact in the worst case.

The Equifax data breach from 2017 is just one example. In this case an unpatched remote code execution vulnerability in the Apache Struts framework opened the door for the attackers. Equifax (3) estimates that it has spent $1.4 billion so far to recover from the breach.

Have a great week.

References

  1. MSRC Team. Prevent a worm by updating Remote Desktop Services (CVE-2019-0708) – MSRC [Internet]. 2019 [cited 2019 May 19]. Available from: https://blogs.technet.microsoft.com/msrc/2019/05/14/prevent-a-worm-by-updating-remote-desktop-services-cve-2019-0708/
  2. NIST NVD. NVD – CVE-2019-0708 [Internet]. 2019 [cited 2019 May 19]. Available from: https://nvd.nist.gov/vuln/detail/CVE-2019-0708
  3. Olenick D. Equifax data breach recovery costs pass $1 billion [Internet]. SC Media. 2019 [cited 2019 May 19]. Available from: https://www.scmagazine.com/home/security-news/data-breach/equifax-data-breach-recovery-costs-pass-1-billion/

Windows 10 Lean – Microsoft’s essential step (back) to the future?

29 April 2018

The report “Windows 10 Lean: Latest build offers first glimpse of Microsoft’s new cut-down OS” (1) published by Liam Tung on 24 April 2018 at ZDNet made me really curios.

Why is the industry in desperate need of a cut-down Windows OS? To answer this question we need to dig into the history of computing.

Tandberg TDV 1200 Terminal. Picture Credits (2)

Tandberg TDV 1200 (2)

In the nineteen sixties and seventies IT business was largely based on host-based computing. Usually the end-user devices were character based terminals with very restricted functionality. Business reports or letters were a real challenge on a Tandberg terminal with IBM ISPF. Individual changes to the user interface were usually limited to the change of the highlight colors and the function key assignment.

Apollo Domain DN330 Workstation

Apollo Domain DN330 (3)

The introduction of server-based computing in the nineteen seventies was a significant benefit for the end users. Graphics-based workstations, often diskless, opened up new fields of application, e.g. desktop publishing, CAD or CAPE. Here, too, the users had only limited options to customize the user interface or to install applications.

With the introduction of Windows NT AS 3.1 in 1993 everything changed. For the first time an operating system had an easy to use graphical user interface, was easy to operate through this GUI , and had easy to use inbuilt peer-to-peer networking capabilities. This was the Wild West for the users.

Unfortunately, very often the Wild West ended up in chaos. With Windows 2000 everything was under control again. Server-based computing was the standard again, peer-to-peer networking capabilities were hardly used.

SAAS, e.g. O365, OneDrive, Sharepoint Online, Box for Business or Google’s G Suite, takes us eventually back to host-based computing: The cloud is the new host.

Once the industry has adopted SAAS every interaction with the cloud is based on the HTTPS protocol. SMB and all the client-server and peer-to-peer networking capabilities of Windows are no longer needed. Even for printing the IPP protocol can substitute SMB.

Thus it is time to eliminate these networking capabilities from the OS. And with this, we eliminate all this EternalBlue, EternalRomance, WannaCry and NotPetya stuff because lateral movement depends heavily on the Windows Peer-to-Peer networking capabilities.

Chrome OS is Google’s answer to this trend. Will Microsoft follow with Windows 10 Lean?

From Liam Tung’s report we learn:

“Windows 10 Lean was revealed on Twitter by Windows enthusiast Lucan, who noted the heavily cut-down OS has no wallpaper and is missing apps like Registry Editor and Microsoft Management Console, as well as drivers for CD and DVD drives.”

From my point of view that’s not enough to deal with the IT security challenges the industry faces today.

Have a great week.

  1. Tung L. Windows 10 Lean: Latest build offers first glimpse of Microsoft’s new cut-down OS [Internet]. ZDNet. 2018 [cited 2018 Apr 24]. Available from: https://www.zdnet.com/article/windows-10-lean-latest-build-offers-first-glimpse-of-microsofts-new-cut-down-os/

  2. Picture credits: Telemuseet, Wikipedia, https://digitaltmuseum.no/011025208286/datautstyr

  3. Picture credits: Jim Rees, Wikipedia, https://commons.wikimedia.org/wiki/File:Dn330.jpg

Why is the industry such vulnerable against WannaCry and NotPetya style attacks? Part II.

16 July 2017

In part one of this post I discussed the impact of the aging IT infrastructure on the industry’s vulnerability against WannaCry and NotPetya style attacks. Part II deals with the OS basics.

Built-in features of the Windows operating system

Windows is the hacker’s paradise. Not because of the endless stream of vulnerabilities. I my opinion, Microsoft does a good job in managing this.

But because Windows is designed to support the efficient administration of networks with thousands of windows workstations, servers, users and applications.

The authorization subsystem (Active Directory) allows the assignment of fine grained permissions to users and groups to whatever resources, and the authorization check before access to resources in near real-time. It is highly scalable to support a single office LAN as well as a segmented global network.

Built-in utilities like Admin Shares, WMI (Windows Management Instrumentation), netsh, ipconfig, and the net command enable administrators to query and to change workstation, server and user settings across the network and to support efficient software distribution and troubleshooting. Windows Server Update Service (WSUS) supports the administrators in keeping the known vulnerabilities patched.

Everything is of course scriptable with the Windows Command Shell, Powershell and VBScript. All utilities can be leveraged up to a certain extent by every user and fully by administrators.

And of course, also by malware or cyber-criminals. Once a cyber-criminal managed to get on your network with e.g. a RAT (Remote Access Toolkit), he can walk across your network and do his malicious work with just the built-in tools. A download of utilities from a C&C (command and Control) server is not necessary. With this, the cyber-criminal is nearly invisible and he will stay nearly invisible for a long time if he makes no errors.

The Principle of least privilege is implemented in Windows at all levels of the OS stack. This is ensured by the Secure Development Lifecycle (SDL), which is the mandatory Microsoft development policy since 2004. Thus, under normal conditions, the Windows built-in security features would limit the impact of a malware.

Unfortunately, software failures cannot be avoided by the SDL because they are systemic errors – we build them during development right into the software. Once a process state triggers such a systemic error and someone finds a method to reproduce the error condition, the error becomes a vulnerability, e.g. MS017-10. This is no problem unless an exploit is published which allows a cyber-criminal to leverage the vulnerability for e.g. privilege escalation. With this, he gets full access to all the built-in tools and to all processes, including the authorization subsystem.

But even if exploiting a vulnerability leads not to a privilege escalation only some patience is needed. Just probe the network until a user is found who works with permanent administrative privileges. If such a session is hijacked, a cyber-criminal gets full access to all tools and the authorization subsystem on the computer.

With administrative privileges the attacker or malware can dump the authorization subsystem on the computer and extract either the password hashes or the clear text passwords. The example below shows an extract created by MIMIKATZ on a Windows 7 Enterprise Editon Workstation.

C:\Program Files (x86)\mimikatz\x64>mimikatz
.#####.   mimikatz 2.1.1 (x64) built on Jun 18 2017 18:46:28
.## ^ ##.  "A La Vie, A L'Amour"
## / \ ##  /* * *
## \ / ##   Benjamin DELPY `gentilkiwi` ( benjamin@gentilkiwi.com )
'## v ##'   http://blog.gentilkiwi.com/mimikatz             (oe.eo)
'#####'                                     with 21 modules * * */
....

Authentication Id : 0 ; 315690 (00000000:0004d12a)
Session           : Interactive from 1
User Name         : kjochem
Domain            : WIN-2OLSA000OLM
Logon Server      : WIN-2OLSA000OLM
Logon Time        : 16.07.2017 21:31:24
SID               : S-1-5-21-3248755352-2707638487-1840279341-1000
msv :
[00000003] Primary
* Username : kjochem
* Domain   : WIN-2OLSA000OLM
* NTLM     : dd94b116548a739e24ad775193c2d13b <--- Password hash
    ….. 
wdigest :
* Username : kjochem
* Domain   : WIN-2OLSA000OLM
* Password : #Not very12strange! <--- Clear text password
kerberos :
* Username : kjochem
* Domain   : WIN-2OLSA000OLM
* Password : (null)
ssp :
credman :

The extracted passwords can be used for direct login to further systems, the password hashes in Pass-the-Hash attacks on further nodes. In any case the chance of detection is low since the attacker behaves like a normal user.

This is the way NotPetya works and other malware worked in the past and will work in future.

Windows is highly optimized to allow cost effective operation of networks of thousands of computers. This leads automatically to misconfigurations, e.g. through domain based technical accounts with high privileges on all workstations and servers. In combination with users working with permanent administrative privileges the cyber criminal’s life is simplified.

What are mitigating measures?

The selection below makes no claim to be complete.

Migration to Windows 10.

Drop all old-style transportation and authentication protocols during this process. Migration to Windows 10 is the first choice because baseline security in Windows 10 is higher than in Windows 7. For example, the issue with the plain text passwords in the authorization subsystem is gone. But this is not helpful in industry because we must deal for at least 5 to 10 years with Windows 7 or Windows 2008 server and old-style protocols.

Short and mid-term mitigation measures.

  • Reduce the number of users working with permanent administrative rights to zero. This is a leadership task!
  • Implement priority patching of critical systems, especially for those on the perimeter to the production networks.
  • Review all firewall rules. Focus on required connections, limit the use of the SMB protocol as far as possible.
  • Review all technical users. Limit their functionality to the local systems and lowest possible privileges, if possible.
  • Roll out a security incident detection tool (SIEM) to all clients and servers. For example, dumping of processes in memory of a workstation or server is a clear indicator for a hacking attempt. Immediate action upon such events is required.
  • Implement privileged account and session management, in the best case with one-time passwords which are changed after the session ends.
  • Apply the measures to mitigate Pass-the-Hash attacks to all Windows networks. For details please see https://www.microsoft.com/en-us/download/details.aspx?id=36036.

Long-term measures.

  • Microsoft should build a production friendly Windows with limited functionality. This Windows should have a much smaller attack surface than the standard multi-purpose Windows systems of today.
  • The dependency on the SMB protocol for exchange of data between the office and the production networks should be reduced, in the best case to zero.

Have a great week!

Some thoughts on “Ransomware a real risk for SCADA networks”

5 June 2017

“By now the ‘Air gapping’ myth should be expunged from every ICS/SCADA manager on earth.” I really like this statement from Daniel Cohen-Sason, published on 23 May 2017 in the CYBERBIT blog.

From my point of view, the ‘Air Gap’ era ended with the introduction of portable engineering stations about 30 years ago.

Modern OT networks are often designed on the basis of the ISA 95 Standard with network zones and security devices, e.g. firewalls, to control the communications flow between the process control and SCADA systems across the zones. Modern production requires a lot of Machine-to-Machine (M2M) communication between the production networks zones and between the production network and the business network. Besides this M2M communication Human-to-Machine (H2M) communication is required, e.g. for operator access from the business network and for remote maintenance.

For M2M and H2M interaction communication channels must be opened on the firewalls. With this, there is always a chance that malware can spread across such required connections. Furthermore, cyber attackers can gain access, e.g. through remotely exploitable vulnerabilities, after they hijacked a M2M communications endpoint in the business network. We dealt with this very effectively in the past 20 years.

Many of the required connections use the SMB protocol for exchange of data. That’s no problem per se. The problem is, that we still use Windows 7 and Windows Server 2008 in the manufacturing industry which cannot work with the latest versions of the SMB protocol for data exchange.

Since WannaCry exploited a vulnerability in SMB version 1.0, it was only a matter of time before WannaCry would find its way across a required connection from the business network to the production network.

How to deal with the problem?

  • Priority patching.

The systems at the border between the business network and the production network must me patched with highest priority. Although this is somewhat tricky to achieve in WSUS, it’s worth to deal with this WSUS feature. In addition to the operating system components, all application components must be patched as well. The same applies to Linux based systems.

  • Deactivating SMB.

Is a great means in the case of an emergency, and part of a long-term data exchange strategy.

  • Set up asset and vulnerability management.

At least all systems at the endpoints of required M2M and H2M connections must be included. This enables you to evaluate the scale of the problem in the case of a new vulnerability.

  • Faster innovation cycles.

At least for the systems at the perimeter of the production network we must allow for shorter innovation cycles. With Windows 8, Windows 10, and Windows Server 2012, new versions of the SMB protocol are used which are not affected by WannaCry. Don’t forget to deactivate the SMB V1.0 compatibility in the this versions.

This includes the technology used for data exchange. For example, the widely used Robocopy fosters the spreading of WannaCry because it is based on the SMB protocol.

  • Increase the level of isolation.

Start with challenging the required M2M and H2M connections. Eliminate every connection without a business purpose. For the remaining, check whether the best available security technology is used.

Take care!

SambaCry – Keep Calm and Carry on

28 May 2017

Actually, it was only a matter of time until Samba, the popular implementation of the Windows SMB services on Linux and Unix, was hit by a WannyCry akin malware. All version of Samba from 3.5.0 onwards are vulnerable to CVE-2017-7494 or SambaCry.

The good news is that this vulnerability is complex to exploit: An attacker must upload a shared library with the malicious code to a writable samba share and then cause the server to load and execute it. Patches are available for the major Linux distributions.

How large is the problem? Shodan finds 471,578 systems which are exposed to the Internet.

SambaCry Shodan Map

SambaCry Shodan Map. Click to enlarge.

90% of the systems are operated in 3 countries, United Arab Emirates, Argentina, and Italy by the major telecommunication providers in these countries. Since an older version of Samba is used on this internet routers they are not vulnerable against SambaCry.

Most of the work has to be done in the United States and Germany. Although only 2 % of the affected systems are operated there, many organizations are affected.

Don’t panic! Even though many systems are affected by SambaCry this does not mean, that they are vulnerable against the exploit. Remember, you have to upload the malicious code to a writable Samba share on a server first. Under normal conditions, Linux admins don’t open Samba shares writable to everyone on servers exposed to the internet.

Thus, the best approach to reduce the risk is to check the Linux systems at the network perimeter with publicly available Samba shares and to close the writable, if any. As always, it is good to have an up-to-date system inventory in place. This will reduce the amount of work dramatically.

Take care! And don’t forget to check the network perimeter to your production networks.

WannaCry, Rumsfeld and Production Firewalls

21 May 2017

Today, Firewalls are the preferred means to separate a production network from a company’s intranet. Firewall configuration is performed by the Rumsfeld Conundrum: Block everything you don’t know!

Rumsfeld Conundrum for firewall configuration

Rumsfeld Conundrum for firewall configuration

For production management and IT and OT operations, we need some communication between systems in the company intranet and the production network. These required (known) connections are defined in the firewall rule base. The firewall allows communication between these known systems, and blocks any other connection attempts.

As long as the SMB V1.0 protocol is not used for communication across the firewall, the Rumsfeld Conundrum works pretty well.

Unfortunately, the SMB protocol is frequently used to implement required connections between Windows-based computers in the company intranet and the production network, e.g. for the exchange of manufacturing orders. With this, production systems become vulnerable to WannaCry although a firewall is in place because the firewall does not block communication across required connections. In the worst case, if WannaCry spreads across required connections to systems in the production network, this may result in loss of production.

Immediate action is required. The firewall rule base is a good starting point to determine how big the problem is, and to identify the systems that must be immediately patched or otherwise secured, if patching is not possible due to technical or regulatory restrictions.

Firewalls are an indispensable part of a defense in depth concept, but plain packet filtering is no effective means against attacks like WannaCry.

Have a good week, and take care of you production networks.

You may Wanna Cry on Monday morning if your Anti-Phishing Training was no success

14 May 2017

In the past days WannaCry was making the headlines. I found a really well written post on Binary Defense which explains the basics of the initial infection as well as the propagation method.

WannaCry does not use any heavy sophistication methods for delivery. It first uses a password protected zip file, which has a document inside.

Packaged this way anti-malware solutions cannot scan the attachment because they can’t enter the password for opening the attachment, although it is stated in the email body. Even APT (Advanced Persistent Threat) solutions may fail if they are not properly configured.

If your Anti-Phishing Awareness Training was successful, the chance of an infection is small.

In addition, it makes sense to block incoming mails with zip files, which cannot be inspected by the anti-malware solution. Don’t deliver them to the users junk mail folder, block them on the mail gateway.

This gives you the time to implement patch MS17-010, if you have not yet done so. Or isolate the affected systems from the network, if patching is not possible, e.g. in GxP controlled environments.

Take care!