Tag Archives: Security

Microsoft Exchange Vulnerability affects all Exchange versions

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CVE-2020-0688 | Microsoft Exchange Validation Key Remote Code Execution Vulnerability

Security Vulnerability

Date of Publishing: February/11/2020

Microsoft has announced a vulnerability has been found in all Exchange Server 2010 through 2019 versions, The vulnerability allows an attack to send a specially crafted request to the affected server in order to exploit it.

When could this happen?

A remote code execution vulnerability exists in Microsoft Exchange Server when the server fails to properly create unique keys at install time.

Knowledge of a the validation key allows an authenticated user with a mailbox to pass arbitrary objects to be deserialized by the web application, which runs as SYSTEM.

The security update addresses the vulnerability by correcting how Microsoft Exchange creates the keys during install.

Affected Versions:

  • Microsoft Exchange Server 2010 Service Pack 3 Update Rollup 30
  • Microsoft Exchange Server 2013 Cumulative Update 23   
  • Microsoft Exchange Server 2016 Cumulative Update 14   
  • Microsoft Exchange Server 2016 Cumulative Update 15   
  • Microsoft Exchange Server 2019 Cumulative Update 3   
  • Microsoft Exchange Server 2019 Cumulative Update 4

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Solution:

Until now Microsoft has not provided any solution or work around to cover this vulnerability.

Mitigations

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

NOTE:

Keep an eye on the below link for any change

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0688

Microsoft Windows 10 security updates KB4532695 and KB4528760 causes TPM driver to fail and results in windows 10 BSOD

Update: For the solution scroll to the end of the page.

Windows 10 Update :

Yesterday and today Microsoft released KB4532695 and KB4528760 causes TPM 2.0 driver to stop functioning and causes BSOD with error “Memory Management” Issue.

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Windows Hello Face Authentication

In the first KB Microsoft says they have improved the accuracy of Windows Hello Face authentication however this would cause your PIN to be reset, TPM driver stop functioning and BitLocker to change in Pause state.

Check KB Article here

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The BSOD will generate an event ID 1001 stating the bugcheck code and saves a dump. ( I haven’t analyzed that yet).

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After Uninstalling the updates it was a no go but at least the Memory Management BSOD stopped..

Interesting thing is that not just TPM stopped, now even Virtual Box says no Virtualization Capabilities supported on my Device which I had over 20 VMs on it and was working fine also before these updates.

The TPM is indeed firmware as it’s fixed on the board..

In the event viewer related to Device Manager (Trusted Platform Module 2.0) I see couple of errors sourced from Kernel-PnP and UserPnp

KernelPnp error

Device ACPI\MSFT0101\1 had a problem starting.

Driver Name: tpm.inf
Class Guid: {d94ee5d8-d189-4994-83d2-f68d7d41b0e6}
Service: TPM
Lower Filters:
Upper Filters:
Problem: 0xA
Problem Status: 0xC0000001

—-

Device ACPI\MSFT0101\1 was configured.

Driver Name: tpm.inf
Class Guid: {d94ee5d8-d189-4994-83d2-f68d7d41b0e6}
Driver Date: 06/21/2006
Driver Version: 10.0.18362.267
Driver Provider: Microsoft
Driver Section: Tpm2BaseInstall
Driver Rank: 0xFF0002
Matching Device Id: *MSFT0101
Outranked Drivers: tpm.inf:ACPI\MSFT0101:00FF0001
Device Updated: true
Parent Device: ACPI_HAL\PNP0C08\0

—-

UserPnp (Informational event) happens after Kernel-Pnp fail

Driver Management concluded the process to install driver tpm.inf_amd64_aaaa339206cb706e for Device Instance ID ACPI\MSFT0101\1 with the following status: 0x0.

Solution:

After two days of struggling I managed to find the solution.

Disable Device Guard from Group Policy and PowerShell.

  • To disable from PowerShell you’ll need to download the Device Guard and Credential Guard hardware readiness tool which contains a script that would disable/enable Device Guard.
  • Use the following cmdlet .\DG_Readiness_Tool_v3.6.ps1 -Disable after extracting the the DG readiness tools from the link below

https://www.microsoft.com/en-us/download/details.aspx?id=53337

  • From Run type gpedit.msc and launch Group Policy then navigate to Computer Configuration > Administrative Templates > System > Device Guard and set “Turn On Virtualization Based Security” To Not Configured.

Once this is done, Restart your Computer and Press F3 to disable Device Gaurd twice. When restarting the Computer will restart again and you’ll see that your TPM is back to normal.

Warning for millions of Windows 10 users

The “Windows List” website, which follows the news of the famous operating system “Windows 10“, issued a warning to the users of the Operating system after it monitored a new security update for the operating system, which is “KB4528760” causing serious problems, noting that the problem “appears to be widespread now.”

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In its interpretation of the sequence of events, the site says that this update initially fails to install on the device, issuing “a number of general error messages” that do not provide any indication of the cause of the problem, then the problem escalates as the next time you restart the computer it fails to boot .

“The recent update KB4528760 for Windows 1909 (the Windows build version number) appears to cause problems with some computers and prevents them from Starting up, causing the oxcooooooe error code. The number of devices affected by this problem has increased after installing this update,” says a user on the official Microsoft Community Forum. .

Image result for windows 10 error code oxcooooooe

Some users attribute the problem to Microsoft’s Connect app, which the company has terminated. Although it is not the only scenario of the cause of the problem, the users who installed the app or had it installed and then uninstalled it, have been particularly severely affected. It is only Windows Vista that completely re-installs the Windows 10 operating system.

What increases the importance of the warning issued by “Windows Light” is precisely that Microsoft is not yet aware of this problem. Indeed, until the moment the company states on the support page of the latest update that it is “currently not aware of any problems with this update.”

This is a recurring series of slow responses in recent years, as Windows 10 users have experienced problems caused by system updates, and this is disappointing because it encourages users to continue to download the update that might harm their computers

The good thing here is that Microsoft is working on substantive modifications to improve the updates of “Windows 10”, but the bad thing is that the process of testing the modifications in its entirety is fundamentally flawed, according to the site mentioned

Microsoft exposes a security issue that affects millions of Windows 10 computers, RDP and DHCP on win2008R2

Windows 10 Crypto API Spoofing

Microsoft has released a new security patch for a vulnerability that could affect millions of Windows 10 Users world wide.

A decades old API

The decades old CryptoAPI tool validates and signs packages/software which could be utilized by hackers/developers to sign and execute illegitimate software thus would allow users to run anything without user’s nor Antivirus/Internet Security software’s notice.

Microsoft mentioned that the vulnerability could also allow hackers to change or modify encrypted communications.

It’s important to mention that CryptoAPI is a legacy API that’s being replaced by a new CNG (Cryptography Next Generation API) which also supports CryptoAPI.

CryptoAPI Key Storage Architecture

cryptoapi architecture

Download Patch

Direct Download

https://www.catalog.update.microsoft.com/Search.aspx?q=KB4528760

CVE

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0601

Windows 2008 R2, Windows 7 RDP

A day ago Microsoft released two very important security patches on May 14, 2019.

One of these patches has been detected in the RDP service (CVE-2019-0708) which affects Windows 7 and Windows 2008 R2.

According to MS’s Article a remote code execution vulnerability exists in Remote Desktop Services – formerly known as Terminal Services – when an unauthenticated attacker connects to the target system using RDP and sends specially crafted requests.

No Authentication or Interaction needed

This vulnerability is pre-authentication and requires no user interaction. An attacker who successfully exploited this vulnerability could execute arbitrary code on the target system.

An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

When look at CVE-2019-0708, which is related to the RDP service, we see that attackers are able to run code on systems by sending specially produced packages without any user interaction and authentication and manage to install malware like Ransomware or other execution files.

Download Patch

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0708

Windows 2008R2, 2012R2, 2016 and 2019 DHCP

The other one is in the DHCP service (CVE-2019-0725), and both vulnerabilities are very critical.

A memory corruption vulnerability exists in the Windows Server DHCP service when processing specially crafted packets. An attacker who successfully exploited the vulnerability could run arbitrary code on the DHCP server.

Download Patch

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0725

Sources:

Microsoft, NSA, Other Security Researchers

Powershell script to audit users who authenticated against DC servers

The story:

I have got a request from a client asking to find out which server(s) is using which domain admin or a highly privileged account as a service.

To find this I already wrote a powershell script that does this, Search the non standard/(Domain only users) and show the services and name of the servers where those accounts are configured on utilizing Remote powershell to do so and the use of a Domain Admin user.

You can refer to this link to see this article by clicking here

Creating the script process:

The same client wanted to also know which of those accounts did authenticate and wanted to know from which server/Computer did the request originate from and to which DC did it go.

I have started thinking of the process of doing so by again utilizing remote PowerShell to check against certain security events on AD to check which user among the Domain admin members did authenticate.

After sometime and with the help of some forums I managed to get script ready which looks in all Domain Controllers for users that are members of the Domain Admin groups who triggered an event ID 4624 and from which Computer did this request came from.

The Script :

# Get domain admin user list
$DomainAdminList = Get-ADGroupMember -Identity 'Domain Admins'
# Get all Domain Controller names
$DomainControllers = Get-ADDomainController -Filter * | Sort-Object HostName
# EventID
$EventID = '4624'
#
# Get only last 24hrs
$Date = (Get-Date).AddDays(-3)
# Limit log event search for testing as this will take a LONG time on most domains
# For normal running, this will have to be set to zero
$MaxEvent = 100

# Loop through Dcs
$DALogEvents = $DomainControllers | ForEach-Object {
    $CurDC = $_.HostName
    Write-Host "`nSearching $CurDC logs..."
    Get-WinEvent  -ComputerName $CurDC -FilterHashtable @{Logname='Security';ID=$EventID;StartTime = $Date} -MaxEvents $MaxEvent |`
    Where-Object { $_.Properties[5].Value -in $DomainAdminList.SamAccountName } |`
    ForEach-Object {
        [pscustomobject]@{SourceIP = $_.Properties[18].Value; SamAccountName = $_.Properties[5].Value;Time = $_.TimeCreated;LogonEventLocation = $CurDC}
    }
}
$DALogEvents

How to run:

The Script must be run on DC with a privileged account in order to get the write results, The default time interval is set to 3 days but you can choose to increase that.

You can also change the default group where you want to search for members by changing Domain Admin groups to something else.

Screenshot of the result