Technical Info

Viewing .crt and .pem certificate files & elliptic curve technology

Usually interacting with a web site certificate requires clicking through the certificate tabs and fields that can be slow. This article describes how to export the certificate and view the .crt or .pem file.

supportmicrosoftcom

Click ‘Export’ to download the .crt and .pem files from the web site. In our example we have used one from Microsoft:

https://support.microsoft.com

The CertUtil is built into MS Windows and is available at the command prompt. From the MS Windows start menu launch “cmd” to get a command prompt and type the following:

C:\>certutil supportmicrosoftcom.crt > supportmicrosoftcom.txt

View the text file and it looks like this:

X509 Certificate:
Version: 3
Serial Number: 200002287cdc13c03ed292a74300000002287c
Signature Algorithm:
Algorithm ObjectId: 1.2.840.113549.1.1.11 sha256RSA
Algorithm Parameters:
05 00
Issuer:
CN=Microsoft IT TLS CA 2
OU=Microsoft IT
O=Microsoft Corporation
L=Redmond
S=Washington
C=US
Name Hash(sha1): 881a4a74feff4652f354bb510fd3a4eeefe0a1c8
Name Hash(md5): 310cd0eb139f28ab9f55bce673112357

NotBefore: 28/02/2018 10:56 AM
NotAfter: 28/02/2020 10:56 AM

This pipes the output into a text file. It can be useful to view the anatomy of the Microsoft certificate, including:

  • Certicate valid from / to dates.
  • Certificate authority that issued the certificate.
  • Whether it is a wildcard certificate for *.sanitysecurity.com or just for http://www.sanitysecurity.com
  • Public key algorithm is RSA.
  • Public key length is 2048 bits.

We can compare the Microsoft certificate with a certificate from Google for Gmail:

https://mail.google.com

Again, we perform the same command using CertUtil to output the contents:

C:>certutil google-mail.cer > google-mail.txt

We notice the following differences:

  • Public key algorithm is ECC using ECDSA_P256.
  • Public key length is 256 bits.

We can take guidance on key algorithms and key length from NIST in the NIST Special Publication 800-57 Part 3: Recommendation for Key Management. The publication contains the table below that indicates the comparable key lengths for the different key lengths.

Key Type Algorithms and Key Sizes
Digital Signature keys used for
authentication (for Users or Devices)
RSA (2048 bits)
ECDSA (Curve P-256)
Digital Signature keys used for
non-repudiation (for Users or Devices)
RSA (2048 bits)
ECDSA (Curves P-256 or P-384)
CA and OCSP Responder
Signing Keys
RSA (2048 or 3072bits)
ECDSA (Curves P-256 or P-384)
Key Establishment keys
(for Users or Devices)
RSA (2048 bits)
Diffie-Hellman (2048 bits)
ECDH (Curves P-256 or P-384)

Unfortunately, since the disclosures from Edward Snowden on the activities of the NSA there have been some discussion regarding whether Elliptic Curve algorithms can be trusted. The issue is about the source of the seed number that the Elliptic Curve algorithms rely upon. Some background information on elliptic curve technology can be found below. As is often the case with cryptography, the strength of the protection relies upon the encryption algorithm and how it is used.

We hope this helps, @SanitySecurity

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Technical Info

Signing-Out of Google Chrome

Google’s change to the Chrome has forced some information security specialists to reassess their use of the web browser due to concerns about user privacy and trust. Here is one article from that describes why the cryptographic engineer won’t be using Chrome going forward.

The real purpose of the feature seems unclear, we prefer it when our web browsers don’t know who we are. For this reason we do not sign-in to Chrome or use the pocket feature in FireFox. Perhaps the motives of Googleare innocent enough. But Google logs you in automatically when you login to Google services like Gmail, meaning that you opt-out to avoid the feature. Whereas you opt-in to use the pocket feature in FireFox.

As of Chrome browser version 70 you can now opt-out of automatic Chrome login. You can do this from the “Settings” and search for “Allow Chrome sign-in”:

ChromeSettings.png

chrome://settings/?search=allow+chrome

You need to restart the web browser for the changes to take effect. Before restarting you might also want to clear you Google cookies. Navigate to Google, and press either CTRL+SHIFT+I or F12 to open the Developer tools. Select Application > Cookies and clear all cookies.

ChromeCookies.png

We really hope that Google decides to disable the feature by default, making this article irrelevant. Alternatively, they could remove the feature altogether.

We hope this helps, @SanitySecurity
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Technical Info

How To Find The Checksum Of A LibreOffice Download On Microsoft Windows

Open source software products like LibreOffice or Apache provide a checksum. This article describes how to use the checksum to verify the integrity of the software you download.

The checksum is a way of verifying that the product you have downloaded onto your computer is the same as the product published on the vendor’s website. In other words, the attacker has not managed to inject malware or other nasties into the software product on the vendor’s website or while you downloaded it. Verifying the checksum is a part of good computer hygiene that will help to protect your computer.

To verify the checksum you calculate the hash value of the software product downloaded on to your computer. The MD5 and SHA1 hash algorithms gives some confidence about the data integrity of the download, as they can be subverted by an attacker. The SHA256 hash algorithm gives more confidence about the data integrity of the download, as it is a cryptographically stronger hashing algorithm.

1. First navigate to the target website and download the software product to your computer, like this:

LibreOfficeDownload.png

https://www.libreoffice.org/download/download/

2. Click on the ‘Info’ link below the ‘Download’ button. The ‘Info’ web page displays the checksums of the current version of LibreOffice.

LibreOfficeChecksum.png

https://download.documentfoundation.org/libreoffice/stable/6.1.2/win/x86_64/LibreOffice_6.1.2_Win_x64.msi.mirrorlist

3. From the Microsoft Windows Command Prompt, navigate to the download and use the “certutil” command to calculate the hash value. No other software is required, it is already built in to Microsoft Windows.

Microsoft Windows [Version 10.0.17134.376]
(c) 2018 Microsoft Corporation. All rights reserved.

C:\>cd Downloads

C:\Downloads>certutil -hashfile LibreOffice_6.1.2_Win_x64.msi sha256
SHA256 hash of LibreOffice_6.1.2_Win_x64.msi:
ddd4cf674cc2543f7d5f375562853386793fc6003fe70fa270baf905af7f00fe
CertUtil: -hashfile command completed successfully.

4. Copy the SHA256 value and search for the value in the ‘Info’ web page. If the SHA256 value is highlighted in the ‘Info’ web page gives us confidence about the data integrity of the download.

LibreOfficeChecksumSearch.png

We hope this helps,
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Technical Info

Review of 3 (ISC)2 CISSP Exam Preparation Books

At SanitySecurity we strive towards a high degree of knowledge of information security, both in the theory and application, this includes becoming (ISC)2 CISSP certified.

In this article we described three books that we have recently used to prepare for the (ISC)2 CISSP exam. The books are reviewed in sequence of thickness. All three books we reviewed are recommended but for very different readerships.

Here are some general comments on all three books:

  • We found that all three books failed to describe updated law changes, such as US Privacy Shield, EU General Data Protection Regulation (GDPR), or AU Notifiable Data Breaches (NDB). The third Australian law will become more significant as countries implement similar laws. From the three updated law changes, we noticed that even newer editions of the ‘For Dummies’ book only covers EU GDPR.
  • The syllabus for the (ISC)2 CISSP exam was changed in April 2018. Updated versions of these books that reflect the syllabus changes will be published before the end of 2018. All three books we reviewed were published before the April 2018 syllabus changes were published.
  • We found that all three books focus heavily on the first 3 domains but are light on detail for the later 5 domains. This is fine if you are familiar with these later 5 domains, otherwise you might need to do more reading for yourself.

Full disclosure: SanitySecurity has no commercial relationship with any publisher at the time this article was published. If a publisher would like to deliver a truck full of scotch and cash then please contact us for the delivery address.

Eleventh Hour CISSP: Study Guide

‘Eleventh Hour CISSP: Study Guide’ by Joshua Feldman, Seth Misenar, Eric Conrad
Recommended for: Last minute revision before the exam.
Publication date January 2017, the ‘middle-child’ of the three books.
This book is short an sweet, and makes good points quickly. The authors cut to the core of points not addresses in the other two books that are much thicker. This makes it a great book for last minute revision before the exam.
A few points seem to be incorrect. For example, page 28 describes NIST 800-30 and a nine step risk analysis process. NIST 800-30 actually describes 4 steps for a risk assessment.
Test material: The only test questions are the ‘top five toughest questions’ at the end of each chapter. There is no material explictly associated with the book. After a little digging we found some online test material directly from the Elsevier / Syngress publisher. We have been unable to use the test material as we faced difficulties with the required version of Adobe Flash.
Elsevier online practice tests
Conclusion: We found this book to be accessible and can be read from cover to cover.

CISSP For Dummies

‘CISSP For Dummies’ by Lawrence C. Miller and Peter H. Gregory
Recommended for: Information security professionals that have experienced in some domains but would like a book that covers all 8 domains.
Publication date May 2016, the oldest of the three books.
This book is also to the point, but provides additional explanation on points without going into too much detail.
There are lots of useful references to other web sites and other ‘For Dummies’ books. The book contains mixed messaging regarding whether they cover the entire syllabus, sometimes “yes” and sometimes “no, read more”.
The book makes interesting points about the application of information security, for example regarding safety for security professionals living in an IoT world.
Test material: The book includes access to an extensive online test suite available from the Wiley Test Bank website. Simply create an account and register your books using details contained in the print or ebook.
Conclusion: We found this book to be accessible and can be read from cover to cover. It provides a useful level of depth and is our faourite of the three books.

CISSP All-in-One Exam Guide

‘CISSP All-in-One Exam Guide’ by Shon Harris and Fernando Maymi
ISBN13 9780071849272
Recommended for: Professionals that are new to information security, such as those professionals without the 4 to 5 years of experience and aim to become (ISC)2 CISSP Associates.
Publication date January 2018, the most recent addition of the three books.
Despite having been published relatively recently, the book fails to mention US-EU Privacy Shield or GPDR. Instead, the book just describes that Safe Habor is no longer in place. The book contains other out of date points, such as referring to OS X not macOS High Sierra.
The book contains great detail about the the theory and application of information security in the business world, as well as hard-won lessons from difficult experiences. For example: how information security is driven by and integrates with business decisions and business risk.
This book paints a much bigger picture, but some of the language is unclear making for opaque patches. We also disagree with some points. For example: 339pg states that Polish cryptographers broke the Enigma code and gave Britain insight into Germany’s attack plans and military movement, although Polish cryptographers certainly played a key role. We think that this statement misses out on the work performed by the team at Bletchley Park.
Test material: The book includes a CD-ROM that includes an extensive testing software. We successfully installed the software on MS Windows, not Apple macOS or Linux. This means that you might have limited access to the testing software, depending on your access to the computer containing the installed software. In other words, if you use a tablet and smartphone then you might have very limited access.
Conclusion: We found this book is too thick to read from cover to cover but the level of detail makes it a great resource to dive into for specific subjects. It will almost certaintly provide more comprehensive information that what you will likely find on Wikipedia or from a Google search.

We hope this information is useful to information security professionals who are currently considering taking the (ISC)2 CISSP exam.

Matt SanitySecurity

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Technical Info

Finding the Hash Value of a File on Microsoft Windows

Many vendors provide a hash value along with the file download itself. These hash values were previously generated using SHA1 or MD5 hash algorithms, but these hash algorithms have become weaker as computers have become faster and vulnerabilities have been identified in the hash algorithms. For these reasons hash values are typically generated using SH256 or stronger hash algorithms.
The idea is to generate the hash value on your computer using the file downloaded and compare it against the hash value published on the vendor’s web site. This validates that the file downloaded has not modified while it was in-transit over the Internet. In other words, have you downloaded the same file onto your computer that the vendor has published on their web site? There are two tools to generate the hash value of a downloaded file on Microsoft Windows. Both FCIV and CertUtil are available from Microsoft for free and are command line utilities.
Of course, an attacker could modify both the file download and the hash value published on their website. In this case there is no indication that the file download and the hash value have been compromised. For example, this happened to Linux Mint in February 2016 in a ‘supply chain’ style attack:

FCIV

FCIV stands for ‘File Checksum Integrity Verifier’ and was released in May 2004. It is a separate utility that can be downloaded from Microsoft. The ‘fciv.exe’ file then needs to be made available through the system environment variables in Microsoft Windows.
FCIV is a short, concise command. However, it can only compute SHA1 and MD5 hash algorithms. This makes it unsuitable for modern hash values that use stronger hash algorithms.
Example:
fciv [hash_algorithm] [hash_file]

C:>fciv -sha1 "./hello-world.txt"
//
// File Checksum Integrity Verifier version 2.05.
//
b6fe6281d53e8a66d6ab47e0a39a809dad901a0e ./hello-world.txt

CertUtil

CertUtil is a powerful command included in Microsoft Windows as part of Certificate Services. No download or modification of the system environment variables is required. More information about the command is available here:
CertUtil is a longer command. However, it supports MD2, MD4, MD5, SHA1, SHA256, SHA384, and SHA512. It also seems to receive updates by Microsoft.
Example:
certutil -hashfile [hash_file] [hash_algorithm]

C:>certutil -hashfile "./hello-world.txt" sha1
SHA1 hash of ./hello-world.txt:
b6fe6281d53e8a66d6ab47e0a39a809dad901a0e
CertUtil: -hashfile command completed successfully.
We hope this helps,
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