Last Update: April 29, 2024 I’ve previously explained how Chromium-based browsers assign a “danger level” based on the type of the file, as determined from its extension. Depending on the Danger Level, the browser may warn the user before a file download begins in order to confirm that the user really wanted a potentially-dangerous file.Continue reading “SmartScreen Application Reputation, with Pictures”
Tag Archives: Authenticode
Cheating Authenticode, Redux
Back in 2014, I explained two techniques that have been used by developers to store information in Authenticode-signed executables without breaking the signature. Recently, Kevin Jones pointed out that Chrome’s signed installer differs on each download, as you can see in this file comparison of two copies of the Chrome installer, one downloaded from IEContinue reading “Cheating Authenticode, Redux”
SHA256 and Authenticode REDUX^2
Note: Microsoft has not confirmed this change yet; analysis below comes from looking at behavior of 14 signed installers. In December of last year, I wrote about all of the different places hashes are used in code-signing. Then, in January I blogged that Windows 10 had stopped accepting SHA-1 certificates and certificate chains for Authenticode-signedContinue reading “SHA256 and Authenticode REDUX^2”
Authenticode and SHA1–Redux
I tried to install Telerik DevCraft Ultimate, but Windows 8.1 and Windows 10 blocked it: “Unknown Publisher”? Hrm. That’s weird. I know Telerik signs their code and I was pretty sure their code-signing certificate is SHA256, so the new restrictions on SHA1 in code-signing shouldn’t be a problem, right? Sure enough, the code is signed with a SHA256Continue reading “Authenticode and SHA1–Redux”
SHA-1 Certificates Blocked By Authenticode
Twitter started to light up a bit tonight with folks who are having problems with signatures; both third-party ISVs: … and even Microsoft’s own SysInternals utilities show1 an error: Developers are surprised to see their workflow suddenly broken and wonder why. The problem is outlined here – the tl;dr is that you must use a SHA256-signedContinue reading “SHA-1 Certificates Blocked By Authenticode”
Authenticode in 2016
Last month, I noticed that my eToken USB code-signing key only supports SHA1 and not SHA256. I began hunting for a replacement that can sign using the stronger hash. Fortunately, I didn’t have to look far—the Yubico YubiKey 4 is $40 and supports SHA256, RSA 4096, and ECC p384. Beyond supporting stronger algorithms, it seems toContinue reading “Authenticode in 2016”
Hashes and Code-Signing
I’ve written a few articles about using Authenticode to sign your code to help prevent attacks, increase user confidence, and reduce interference from security software like Windows SmartScreen. You can read the overview, discussion of code-signing tokens, and “tricks” you can use to shoot yourself in the foot by adding data to a file withoutContinue reading “Hashes and Code-Signing”
Security UI
Over a decade ago, Windows started checking the signature of downloaded executables. When invoked, Attachment Execute Services’ (AES) UI displays the publisher’s information for signed executables; unsigned executables instead show a security prompt with a red shield and a bolded warning that the publisher of the file is unknown: In contrast, signed executables show aContinue reading “Security UI”
Authenticode and ClickOnce
On my old IEInternals blog, I posted a fair bit about using Authenticode to sign your programs so that their origins could be identified and to avoid triggering warnings from SmartScreen. My last post on that blog before Microsoft took it away was about using a hardware token to improve security of your certificate’s privateContinue reading “Authenticode and ClickOnce”
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