BSI veröffentlicht Hardening Guide, Protokollierungs-Empfehlung und zugehörige GPOs für Windows 10 im Rahmen der SiSyPHuS-Studie

Wir freuen uns, dass das Bundesamt für Sicherheit in der Informationstechnik (BSI) im Rahmen des gemeinsam mit ERNW durchgeführten SiSyPHuS Win10-Projekts (Studie zu Systemintegrität, Protokollierung, Härtung und Sicherheitsfunktionen in Windows 10) heute (ca. 10 Uhr) die nächsten drei Arbeitspakete veröffentlicht:

  • Empfehlung zur Härtung von Windows 10 mit Bordmitteln
  • Empfehlung zur Konfiguration der Protokollierung in Windows 10
  • Gruppenrichtlinien zu den Konfigurationsempfehlungen für Härtung und Protokollierung für Windows 10

In den Dokumenten finden sich unterschiedliche Empfehlungen für Domänenmitglieder (mit normalem und mit hohem Schutzbedarf) und Einzelplatzrechner. Die Dokumente bauen auf den Empfehlungen von Microsofts Security Baseline und dem CIS Benchmark für Windows 10 auf und ergänzen diese in von Microsoft und CIS nicht betrachteten Bereichen oder modifizieren sie dort, wo es aus Erfahrung von ERNW im Hardening von Windows-Systemen sinnvoll ist.

Sie finden die Dokumente hier.

Wir hoffen, damit zur Sicherheit von Windows-Umgebungen beitragen zu können, und wünschen Ihnen viel Spaß bei der Lektüre!


German Federal Office for Information Security (BSI) Publishes Hardening Guideline, Logging Guideline And Related GPOs for Windows 10

We are happy to announce that today the BSI publishes several documents that ERNW created as part of the long-term SiSyPHuS Win10-Project (ger: “Studie zu Systemintegrität, Protokollierung, Härtung und Sicherheitsfunktionen in Windows 10”, en: “Study on System Integrity, Logging, Hardening and Security relevant Functionality in Windows 10”):

  • Hardening Guideline
  • Logging Guideline
  • GPOs for the Guidelines

The guidelines are built on recommendations from Microsoft´s Security Baseline, CIS Benchmarks and ERNW´s expertise.

You  can find the documents and GPOs here.

Let’s make the Windows world a safer place, and have fun reading!



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Of Corona, Buggy Audio Drivers and Industrial Espionage

The Situation

Last year, the CISO of a customer sent me a laptop for analysis. The reason was that he feared the company could have been victim of industrial espionage. Starting in spring 2020, the IT help desk got several employee laptops with full hard drives, caused by a huge amount of audio recordings. The audio files contained recordings even of highly sensitive telephone conferences. An automated scan on all employee computers for such audio recordings showed that about 300 devices were affected. Continue reading “Of Corona, Buggy Audio Drivers and Industrial Espionage”

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Breaking, Misc

fpicker: Fuzzing with Frida


In this post, I will introduce fpicker. Fpicker is a Frida-based coverage-guided, mostly in-process, blackbox fuzzing suite. Its most significant feature is the AFL++ proxy mode which enables blackbox in-process fuzzing with AFL++ on platforms supported by Frida. In practice, this means that fpicker enables fuzzing binary-only targets with AFL++ on potentially any system that is supported by Frida. For example, it allows fuzzing a user-space application on the iOS operating system, such as the Bluetooth daemon bluetoothd – which was part of the original motivation to implement fpicker.
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ERNW Whitepaper 71 – Analysis of Anti-Virus Software Quarantine Files

I am glad to announce the release of the ERNW whitepaper 71 containing information about quarantine file formats of different AV software vendors. It is available here.

Anti-Virus Software

I took quarantine files from real-life incidents and created some in a lab environment. Afterwards I tried to identify metadata, like timestamps, path names, malware names, and the actual malicious file in the quarantine files. One goal was to use this information to support our incident analyses: Using the results, we can now easily create timelines showing information about quarantined files, extract the detected malware, and sometimes even find information about processes that created the malicious files. Continue reading “ERNW Whitepaper 71 – Analysis of Anti-Virus Software Quarantine Files”

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Having Fun with Google MDM Solution

It’s Friday, you managed to escape for a couple of hours from a busy working day to see a doctor. Now you have to wait in a boring waiting room at the clinic until it’s your turn to see her majesty. What would you like to do in this time? Answer pending business emails, get lost in social media, or choose a new theme to make your iPhone look awesome?  What about: all of the above? It’s nice to have everything on your iPhone: MDM enrollment to access business data, in addition to jailbreak for device freedom. However, MDM solutions ban jailbroken devices, because they are not secure enough to handle sensitive business data. And so, cat and mouse games of jailbreak detection/bypass between MDM solutions and some users develop.

In this blogpost, I highlight how this cat and mouse game with Google’s MDM solution “Google Endpoint Management” is currently going. First, I explain how to bypass jailbreak detection of Google’s MDM solution. Then I show how to manipulate MDM enforced policies on your MDM-enrolled jailbroken device. Since these actions have negative impacts on your device’s security, we’ll also discuss how attackers can exploit this insecure setup to steal business data.

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Breaking, Misc

Root Cause Analysis of a Heap-Based Buffer Overflow in GNU Readline

In the last blog post, we discussed how fuzzers determine the uniqueness of a crash. In this blog post, we discuss how we can manually triage a crash and determine the root cause. As an example, we use a heap-based buffer overflow I found in GNU readline 8.1 rc2, which has been fixed in the newest release. We use GDB and rr for time-travel debugging to determine the root cause of the bug.

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Security Advisories for SolarWinds N-Central

In August 2020 we reported six vulnerabilities in SolarWinds N-Central to the vendor.
The following CVE IDs were assigned to the issues :
  • CVE-2020-25617: RCE in N-Central Administration Console (AdvancedScripts Endpoint)
  • CVE-2020-25618: Local Privilege Escalation from nable User to root (N-Central Backend Server)
  • CVE-2020-25619: Access to Internal Services through SSH Port Forwarding (N-Central Backend Server)
  • CVE-2020-25620: SolarWinds Support Account with Default Credentials
  • CVE-2020-25621: Local Database does not require Authentication (N-Central Backend Server)
  • CVE-2020-25622: CSRF in N-Central Administration Console (AdvancedScripts Endpoint)
The vulnerabilities have been found in the course of an extensive research project, in which we analyze the security of multiple Unified Endpoint Management (UEM) solutions. Similar vulnerabilities have been found in other solutions as we pointed out in previous posts about the Ivanti DSM Suite and Nagios XI. The final outcome of the research project will be published as a whitepaper and possibly conference talk as soon as the project including all disclosure processes concludes.
We will provide a short description of the CVEs outlining the impact of the vulnerabilities. Technical details will be published in a whitepaper as mentioned above. All six vulnerabilities have been verified for SolarWinds N-Central
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