Tag Archives: Cloudflare

September 2019 Update Summary

Today is the 2nd Tuesday of the month, when both Adobe and Microsoft routinely release their scheduled security updates.

Similar to last month Microsoft have released many updates resolving 79 vulnerabilities more formally known as CVEs (defined). It was a light month for Adobe releasing 2 updates resolving 3 vulnerabilities.

Adobe Application Manager: 1x Priority 2 vulnerability resolved (Important severity)
Adobe Flash Player: 2x Priority 3 vulnerabilities resolved (Critical severity)

If you use either of these Adobe products, please install the necessary updates as soon as possible prioritising the Adobe Flash Player update.

This month’s list of Known Issues from Microsoft is available within their monthly summary page and applies to all currently supported operating systems. Almost all issues have workarounds at this time and none appear to be serious issues. The up to date list is available from their summary page.

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:
Microsoft Windows LNK Remote Code Execution Vulnerability: CVE-2019-1280

Microsoft Scripting Engine: CVE-2019-1298

Microsoft Scripting Engine: CVE-2019-1300

Microsoft Scripting Engine: CVE-2019-1217

Microsoft Scripting Engine: CVE-2019-1208

Microsoft Scripting Engine: CVE-2019-1221

Microsoft Scripting Engine: CVE-2019-1237

Windows RDP: CVE-2019-1291

Windows RDP: CVE-2019-1290

Windows RDP: CVE-2019-0788

Windows RDP: CVE-2019-0787

Team Foundation Server/Azure DevOps: CVE-2019-1306

Microsoft Office SharePoint: CVE-2019-1295

Microsoft Office SharePoint: CVE-2019-1257

Microsoft Office SharePoint: CVE-2019-1296

Common Log File System Driver (defined): CVE-2019-1214

Microsoft Windows Elevation of Privilege Vulnerability (defined): CVE-2019-1215


Please install the remaining updates at your earliest convenience.

As per standard best practice; 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.

Mozilla Firefox
On September the 3rd Mozilla released Firefox 69.0 to address the following vulnerabilities and to introduce new privacy features:

Firefox 69.0: Resolves 1x critical CVE (defined), 11x high CVEs, 4x moderate and 3x low CVEs

Firefox ESR 68.1 (Extended Support Release): Resolves 1x critical, 9x high, 4x moderate and 2x low CVEs

Firefox 60.9 ESR : Resolves 1x critical CVE, 7x high CVEs and 1x moderate CVE

Highlights from version 69 of Firefox include:
Blocks 3rd party cookies and cryptominers (using Enhanced Tracking Protection) by default (blocking of fingerprinting scripts will be the default in a future release)

Adobe Flash disabled by default (must be re-enabled if needed)

Separately Mozilla is facing criticism over their plans to gradually roll-out DNS over HTTPS (DoH) later this month since all DNS traffic would go to only one provider, Cloudflare. Google Chrome will implement a similar feature soon (further details are available in the above link also regarding Mozilla).

Details of how to install updates for Firefox are here. If Firefox is your web browser of choice, if you have not already done so, please update it as soon as possible to benefit from the above changes.

Thank you.

DNS Flag Day Aims to Make DDoS Attacks Harder

Since the 1st of February multiple major DNS (defined) resolvers removed resolver workarounds. The resolvers involved in the initiative include ISC, Cloudflare, Facebook, Cisco, Google (among others).

The workarounds were removed to stop DNS queries not compliant with the following official Requests for Comments (RFC) 1035 and 2671 from being completed(resolved). In more depth; the DNS Flag day page explains these workarounds are being removed due to:

The current DNS is unnecessarily slow and inefficient because of efforts to accommodate a few DNS systems that are not in compliance with DNS standards established two decades ago.

To ensure further sustainability of the system it is time to end these accommodations and remediate the non-compliant systems. This change will make most DNS operations slightly more efficient, and also allow operators to deploy new functionality, including new mechanisms to protect against DDoS attacks.

It appears that DNS amplification and DNS flood attacks are the threats attempting to be mitigated with these changes. A full list of the types of DDoS (defined) attacks is available from the following Cloudflare page (at the end of that page):

It will be interesting to see the effect of these changes on the DNS infrastructure when it is again targeted by botnets (defined) (e.g. made up of Internet of Things (IoT)(defined) or compromised systems or by other means. Such botnets can make use a command and control (C2) (defined) infrastructure.

Thank you.

Cloudflare addresses data leak

For 5 days within February this year; an information disclosure issue affected Cloudflare’s infrastructure. This led to their systems inadvertently leaking private session keys, website cookies, encryption keys and passwords.

Why should this vulnerability be considered important?

The scale of the issue was large, affecting an estimated 2 million websites. This flaw was due to a coding error within a parser (defined) (undetected at the time) used to modify HTML webpages and related to how the memory containing buffers (defined) of their NGINX (defined) web server functioned. Google Project Zero vulnerability researcher Tavis Ormandy contacted Cloudflare over Twitter who mitigated the issue in 47 minutes and completed their work in less than 7 hours; an incredibly swift resolution. Cloudflare later noted it would usually take 3 months to resolve an issue similar to this.

How can I protect myself from this vulnerability?

Cloudflare documented their findings of this incident within this blog post. Their analysis shows no evidence of attackers using the leaked information for malicious account access, accessing sensitive information or fraudulent purchases (in the case of exposed credit card numbers).

Cloudflare is continuing to review the leaked information and working to remove it from third party caches. They have committed to a review (both internal and with the assistance of external auditor Veracode) of the parser code which inadvertently lead to this information leakage.

As a precaution I would recommend monitoring any affected accounts for unwanted activity and change passwords and enable 2 factor authentication should any unwanted activity take place. The list of affected websites is here.

Further discussion of the impact of this issue is available from this SANS forum post and this Softpedia news article.

Thank you.