Tag Archives: Pass-the-Hash

Adobe Reader Vulnerability Disclosed

Updated: 26th February 2019
After the update was issued by Adobe; the original researcher who disclosed it found a bypass and again reported it to Adobe. The bypass was assigned another CVE number; CVE-2019-7815

It has now been addressed by a further update made available by Adobe last Thursday. If you use Adobe Acrobat or Reader, please ensure it is up to date:

Thank you.

Original Post
Yesterday; the security firm 0patch released a micropatch for a vulnerability that was publicly disclosed (defined) in late January.

Why should this vulnerability be considered important?
The vulnerability allows for the extraction/disclosure of the NTLMv2 hashes (defined) associated with your Windows login account to be sent to an attacker when you open a specifically modified PDF document, The information is sent via the SMB protocol (defined) to the attacker essentially allowing the document “to phone home” to them.

Adobe Reader DC (2019.010.20069 and earlier) are affected. This vulnerability is similar to a now patched vulnerability from last year namely; CVE-2018-4993, The new vulnerability is caused by the fact that while a user is warned via a dialog box when opening an XML style sheet via the HTTP protocol; when using the SMB protocol and while following a UNC (defined) link; no such warning appears.

How can you protect your organisation and yourself from this vulnerability?
Please apply the update made available by Adobe earlier today. If for any  reason you cannot update right now, please consider the micropatch from 0patch. A YouTube video of the micropatch in action is available from the following link:

The micropatch does not require a reboot. The patch does not need to be uninstalled once you later install the update from Adobe.

Thank you.

April 2018 Update Summary

Update: 5th April 2018:
On the 3rd of April, Microsoft released an out of band security update for the Microsoft Malware Protection Engine. Further details are available in this separate blog post.

Other updates made available by Microsoft for the Spectre Variant 2 vulnerability are:



If any of the above updates apply for your version of Windows, please install them. If the updates are already present or are not required; the installation will not proceed when you manually attempt it.

Separately Microsoft have since issued an update, KB4099950 to resolve the issue detailed below affecting the network adapter on Windows 7.

The new update KB4099950 must be installed before KB4088875 and KB4088878 (I assume if this is not the case that KB4088875 and KB4088878 could be uninstalled first?)

If you were experiencing any of the following issues on Windows 7 or Windows Server 2008 R2, please install the above update to resolve them:

A new Ethernet Network Interface Card (NIC) that has default settings may replace the previous NIC and cause network issues.

Static IP address setting are lost.

These symptoms may occur on both physical computers and virtual machine that are running VMware.

Thank you.

Update: 1st April 2018:
Microsoft have issued an out of band update for Windows 7 SP1 64 bit and Windows Server 2008 R2 SP1 64 bit to resolve a regression (an un-intentional coding error resulting in a previously working software feature no longer working, alternative definition here) which introduced an additional elevation of privilege (defined) security vulnerability in the kernel (defined) of these Windows version, please see my new post for further details.

This post has also been updated with further software releases (please see below).

If you have already checked for updates and are not seeing any being offered for your Windows 7 or Windows 8.1 system, please ensure your anti-malware software is up to date. This article explains why this change was implemented by Microsoft. It also provides recommendations of how to resolve the issue of no updates being available. Windows 10 is not affected by this issue.

A known issue of a second network adapter appearing within Windows 7 has also been documented. If this occurs for you with March’s updates, this news article may be of assistance in resolving it. It is anticipated that Microsoft will resolve this issue in this month’s upcoming security updates.

Thank you.

Original post:
On Tuesday, 10th April Microsoft made available their scheduled security updates to resolve 63 vulnerabilities assigned to the same number of CVEs (defined). Microsoft have provided further details are provided within their Security Updates Guide.

There are 3 knowledge base articles detailing potential issues (some of which are pending resolutions) you may experience upon installing these updates. They are listed below for your reference:





Alongside these updates; Adobe released updates for the following products:

Adobe ColdFusion (priority 2, 5x CVEs)

Adobe Digital Editions (priority 3, 2x CVEs)

Adobe Experience Manager (priority 3, 3x CVEs)

Adobe Flash Player v29.0.0.140 (priority 2, 6x CVEs)

Adobe InDesign CC (priority 3, 2x CVEs)

Adobe PhoneGap Push Plugin (priority 3, 1x CVE)

Non-Microsoft browsers should update automatically e.g. Google Chrome should release a browser update in the coming days or will use their component update feature. Microsoft issued a security advisory containing details of their updates

As always; you can monitor the availability of security updates for most your software from the following websites (among others) or use one of the utilities presented on this page (since Secunia PSI will be phased out on the 20th of April):
US Computer Emergency Readiness Team (CERT) (please see the “Information on Security Updates” heading of the “Protecting Your PC” page):


A further useful source of update related information is the Calendar of Updates. News/announcements of updates in the categories of General SoftwareSecurity Software and Utilities are available on their website. The news/announcements are very timely and (almost always) contain useful direct download links as well as the changes/improvements made by those updates (where possible).

If you like and use it, please also consider supporting that entirely volunteer run website by donating.

For this month’s Microsoft updates, I will prioritize the order of installation below. A useful list of all CVEs for this month is present here:

Microsoft Edge and Internet Explorer (similar to last month multiple versions of Edge and IE affected with many of the CVEs affecting the Microsoft Scripting Engine))

Microsoft Graphics Component consisting of the following 6 CVEs:







Microsoft Wireless Keyboard 850 Security Feature Bypass Vulnerability : described in more detail here.


Separately AMD have issued microcode (defined) updates for Windows 10 Version 1709 to enhance the protection of their customer’s against variant 2 (CVE-2017-5715) of the Spectre vulnerability. Further details of these updates are available within these KB articles: KB4093112 and KB3073119

Please install the remaining updates at your earliest convenience.

As usual; I would recommend backing up the data on any device for which you are installing updates to prevent data loss in the rare event that any update causes unexpected issues. I have provided further details of updates available for other commonly used applications below.

Thank you.


Apple Security Updates:
In late April Apple released updates for Safari, macOS and iOS:

Apple iOS v11.3.1

Apple Safari v11.1

Apple macOS High Sierra v10.13.4


Please see these links from Apple for advice on backing up your iPhone and iPad.

As always; further details of these updates are available on Apple’s dedicated security updates page.

For advice on how to install updates for Apple devices, please see the steps detailed at the end of this Sophos blog post as well as this link (from my “Protecting Your PC” page).

7-Zip 18.05
In late April; version 18.05 of 7-Zip was made available resolving one security vulnerability in it’s RAR packing code. Further details are provided in this linked to blog post.

Other highlights include the inclusion of ASLR on the 32 bit version and high entropy (HE)(defined here and here) ASLR (defined) on the 64 bit version. While the above blog post mentions HEASLR is not enabled, when I tested it with Process Explorer it was showing HEASLR as enabled. That blog post also describes how to add Arbitrary Code Guard (ACG) (defined) protection for 7-Zip on Windows 10. Version 18.01 and later also come with Data Execution Prevention (DEP)(defined here and here).

While 7-Zip is extremely popular as a standalone application; other software such as Malwarebytes Anti-Malware, VMware Workstation and Directory Opus (among many others) all make use of 7-Zip. If you use these software applications or 7-Zip by itself, please update these installed applications to benefit from the resolved vulnerability and the new mitigations.

Wireshark 2.4.6 and 2.2.14
v2.4.6: 10 security advisories

v2.2.14: 8 security advisories

The security advisory wnpa-sec-2018-24 applicable to both of the above versions resolves 10 memory leaks (defined).

As per standard process Linux distributions can obtain this update using the operating systems standard package manager (if the latest version is not installed automatically using the package manager you can instead compile the source code (v2.4.6) or v2.2.14). This forum thread and this forum thread may also be helpful to you with installing Wireshark on your Linux based system.

For Mac OS X and Windows, the update is available within the downloads section of the Wireshark website. In addition, a detailed FAQ for Wireshark is available here.

Wireshark 2.6.0
While this update is not listed as a security update; it is the latest version of Wireshark within the Stable release channel. The older 2.4.x version did not receive a further update. It is very likely version 2.6 will be required to receive future security updates. Further details are available in the release notes of version 2.6. If possible, please consider upgrading to this version in the near future.

Further installation tips are provided above (as per version 2.4.6 and 2.2.14).

Oracle issued updates to resolve 254 vulnerabilities. Further details and installation steps are available here. 14 vulnerabilities affect the Java runtime. 12 of these are remotely exploitable without an attacker needing to obtain a user’s username and password (their credentials).

If you use any of the Oracle products listed here, please install the appropriate security updates as soon as possible.

In mid April; the OpenSSL Foundation issued updates for OpenSSL to address 1x low security vulnerability detailed in this security advisory. To resolve this please update your OpenSSL installations to 1.1.0i or 1.0.2p (as appropriate).

FTP mirrors to obtain the necessary downloads are available from here.

Downloadable Tarballs (compressed/packaged code made for distribution) are available from here.

It should also be possible to use the package manager of a Linux/Unix operating system to update your OpenSSL installation as mentioned within the section titled “Installing updates for Linux distributions” on the “Protecting Your PC” page of this blog.

A Closer Look at CVE-2018-0950
While Microsoft have addressed the vulnerability designated as CVE-2018-0950 (defined) this month; Will Dormann, a security researcher with the CERT Coordination Center has demonstrated further mitigations (defined) you may wish to take. These mitigations (listed at the end of his in-depth discussion) will better defend your system(s) against a variant of this vulnerability which still remains relatively easy for an attacker to exploit.

Thank you.

Windows 10 Credential Guard Bypassed

Despite the demonstrated successes and new security mitigations (specifically Credential Guard) of Windows 10 detailed by Microsoft in the link and PDF document listed below, security researchers from CyberArk have been able to obtain domain admin account (defined) credentials from the Local Security Authority (LSA) Secrets registry hive of Windows 10 using a technique similar to Pass the Hash (PtH)(defined):



Once obtained they injected the credentials into a newly created malicious service to achieve lateral movement (defined) which lead to the compromise of the domain controller (defined). The only requirement of the exploit the researchers developed was obtaining administrator access to a workstation within the domain.

While this could be considered a tall order, a well-designed spear phishing email (defined) with a malicious attachment or a malicious link targeting an unpatched or (zero day, defined) vulnerability on the workstation could be used to achieve privilege escalation (defined) and gain administrative rights (defined). Social engineering (defined) in combination with a malicious USB flash drive could also be a potential way of exploiting this. The methodology of how the CyberArk researchers carried out this exploit is available within their blog.

They also provide a list of mitigations for this exploit, many of which are well known and/or best practice. Microsoft responded to the team’s disclosure of this vulnerability that there will not be a fix since the system must already be compromised for it to succeed.

Thank you.

Disclosed Microsoft Zero Day Under Attack By APT Group

Update: 8th November:
The Microsoft zero day vulnerability discussed in this post has now been patched. Please refer to this post for the appropriate information and download links.

Thank you.

Original Post:
Earlier this week Google publicly disclosed (defined) details of a new zero day (defined) vulnerability affecting supported versions of Windows up to Windows 10. Fortunately, the disclosure only included minimal details.

Why Should These Issues Be Considered Important?
The vulnerability disclosed by Google could result with an attacker being able to elevate their privileges (defined) on an affected system. However, when used in combination with a previously patched Adobe Flash Player vulnerability (reference previous post) this could result in a Windows system under your responsibility or in your ownership to have a backdoor (defined) installed.

Some good news is that this new exploit primarily targets organisations that operate in the following sectors (thus all other organisations are at somewhat reduced risk): government, intelligence or military organisations.

The nature of the backdoor is the decision of the attacker but would usually include a means of remaining persistent on the system and allowing the attacker to remote access the infected system. This backdoor can then be used to move data of the attacker’s choice off the affected system. The APT group known as STRONTIUM by Microsoft (other aliases used in the wider cyber security industry are APT28, also aka Sofacy aka Fancy Bear aka TsarTeam aka Sednit aka PawnStorm). STRONTIUM is also known for moving laterally throughout the network which they compromise (where the pass the hash (PtH) (defined) technique is the method of choice to do so).

How Can I Protect Myself From This Issue?
While a patch from Microsoft is in progress (scheduled for release on the 8th of November): follow safe email guidelines namely don’t click on unexpected/unsolicited links or open potentially dangerous email attachments to prevent the execution (carrying out of) the exploits actions in the first instance.

If you use the Microsoft Edge or Google Chrome web browsers the exploit for the local elevation of privilege vulnerability will be mitigated. This is due to Chrome’s sandbox (defined) blocking the use of API (defined) calls to the win32k.sys driver (defined). This in addition to its existing mitigations when installed on Windows 10 which I previously discussed.

Microsoft Edge on the other hand implements Code Integrity to prevent the next steps of exploitation.

To protect endpoints within your organisation you could consider utilising the logging capabilities of Microsoft EMET and Systinternals’ Sysmon by processing their logs using a SIEM (defined) and taking action when that SIEM a alerts you to suspicion activity. This is especially true since this exploit can occur from within web browsers, the Java JRE, Microsoft Word and Microsoft PowerPoint (namely that these applications are used to open suspicious/untrusted files).

My thanks to a colleague (you know who you are!) for compiling very useful information for this blog post.

Thank you.

Blog Post Shout Out (mid November 2015)

Late last week, the security firm CyberArk published a blog post summarizing the findings of a report they have written:

What percentage of your Windows network is exposed to credential theft attacks? By Amy Burnis (CyberArk)

This report details the consequences that can result when an attacker compromises a Microsoft Windows based computing device within your organization’s network and then uses the credentials of the person logged into that device to access further Windows devices and data within your network.

If an attacker can use privileged credentials to laterally traverse a network (i.e. move from device to device compromising more and more credentials as they do so), eventually the attackers can obtain the credentials of a Windows Domain Administrator account (used to administer your Windows Server based domain controller (defined)), with these the Windows based devices on your network can be completely taken over by an attacker.

This method of attack used to obtain privileged credentials is known as a Pass-the-Hash (PtH) attack. Mitigations to protect against Windows credential theft attacks are discussed on pages 10 and 11 of CyberArk’s report.

I hope that the mitigations and advice discussed in the report mentioned above assist with hardening your organization against such attacks.

Thank you.