Classic Web Vulns Found in Google Search Appliance 7.4

Google Search AppliancesHi all,

I’ve recently found some sort of classic web vulnerabilities in the Google Search Appliance (GSA) and as they are now fixed [0][1][2], I’d like to share them with you.

First of all, some infrastructure details about the GSA itself. The GSA is used by companies to apply the Google search algorithms to their internal documents without publishing them to cloud providers. To accomplish this task, the GSA provides multiple interfaces including a search interface, an administrative interface and multiple interfaces to index the organization’s data. Continue reading “Classic Web Vulns Found in Google Search Appliance 7.4”

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Another Perspective in Vulnerability Disclosure

As you know we (as in ERNW) are quite involved when it comes to vulnerability disclosure and we’ve tried to contribute to a discussion at several occasions, such as Reflections on Vulnerability Disclosure and ERNW Newsletter 50 Vulnerability Disclosure Reflections Case Study.

In this post I want to add (yet) another perspective, motivated by a disclosure procedure which just happened recently. Continue reading “Another Perspective in Vulnerability Disclosure”

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Xen XSA 155: Double fetches in paravirtualized devices

As part of my research on the security of paravirtualized devices, I reported a number of vulnerabilities to the Xen security team, which were patched today. All of them are double fetch vulnerabilities affecting the different backend components used for paravirtualized devices. While the severity and impact of these bugs varies heavily and is dependent on a lot of external factors, I would recommend patching them as soon as possible. In the rest of this blog post I’ll give a short teaser about my research with full details coming out in the first quarter of 2016 .

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Sending Mixed Signals – What Can Happen in the Course of Vulnerability Disclosure


Given there’s quite some speculation and, as we think, misinformation going around we think it’s helpful to add/clarify the following information:

  • we fully comply with the injunction and we have no intentions to violate it. we do not plan to publish any technical information besides the report (agreed upon with FireEye themselves) and the slides (based on the former) anyway. No 3rd parties except for the ones involved (FireEye, lawyers) have received any additional technical information from our side, let alone an earlier version of the report.
  • the injunction covers accompanying details mostly within the architecture space, but not the core vulnerabilities themselves. Those are not part of the injunction.
  • we stand by the timeline as provided below. In particular, the following two points:
    – FireEye received a draft version of the report which had the objectionable material (as identified by the cease and desist letter) fully removed on August 11th.
    – according to the cease and desist letter FireEye’s lawyer sent us, they were informed – from our side – about the planned talk at 44CON on Jul 23rd.
  • there’s an injunction, but not a lawsuit. I used the term “sue” after consulting Merriam-Webster which states: “sue: to seek justice or right from (a person) by legal process”, but this might have been misinterpreted by some readers. As stated, there’s a pending injunction, but not a lawsuit.

Please note that we won’t share legal documents with 3rd parties or publish them as we consider this inappropriate.
Please note further that, during the whole process, our goal was to perform a responsible disclosure procedure with its inherent objectives (namely vulnerability remediation by vendor and education of various stakeholders involved, see also here or here). We consider this disclosure process as concluded. We don’t see a need to add technical details from our side as we feel that the objectives of responsible disclosure are met (not least as patches are released since quite some time and both vendor & finder have released reports).


We’ve just released an ERNW Newsletter titled “Playing With Fire: Attacking the FireEye MPS” which describes several (meanwhile patched) vulnerabilities in FireEye‘s “Malware Protection System” (webMPS) version 7.5.1. Right now Felix gives a talk at 44CON in London on the topic, including some demos. He will release the slides after the talk => to catch the respective announcement you might follow him on Twitter (which is probably a good idea anyway if you’re interested in vulnerability research).

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Reflections on Vulnerability Disclosure

In this post I’ll discuss some aspects of vulnerability disclosure. I don’t want to delve into an abstract & general discussion of vulnerability disclosure (for those interested here’s some discussion in the context of Google’s Project Zero, this is the well-known CERT/CC approach, this a paper from WEIS 2006 laying out some variants, and finally some statement by Bruce Schneier back in 2007). Instead I will lay out which approach we followed in the past (and why we did so) and which developments make us consider it necessary to re-think our way of handling. The post is not meant to provide definitive answers; it was also written not least to provide clarity for ourselves (“write down a problem in order to better penetrate it”) and, maybe, to serve as a starting point for a discussion which will help the community (and us) to find a position on some of the inherent challenges.

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Revisiting Xen’s x86 Emulation: Xen XSA 123

In my last blog post, I gave an overview about recent vulnerabilities discovered in the x86 emulation layer of Xen. While both of the discussed vulnerabilities only allow for guest privilege escalation, the complexity of the involved code seemed to indicate that even more interesting bugs could be discovered. So I spent some time searching for memory corruption issues and discovered a very interesting bug that resulted in XSA 123 . This post gives an overview about the root cause of the bug and a short description of exploitation challenges. A follow-up post will describe possible exploitation strategies in more detail.

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The Dangers of x86 Emulation: Xen XSA 110 and 105

Xen Logo

Developing a secure and feature rich hypervisor is no easy task. Recently, the open source Xen hypervisor was affected by two interesting vulnerabilities involving its x86 emulation code: XSA 110 and XSA 105. Both bugs show that the attack surface of hypervisors is often larger than expected. XSA 105 was originally reported by Andrei Lutas from BitDefender. The patch adds missing privilege checks to the emulation routines of several critical system instructions including LGDT and LIDT. The vulnerable code can be reached from unprivileged user code running inside hardware virtual machine (HVM) guests and can be used to escalate guest privileges. XSA 110 was reported by Jan Beulich from SUSE and concerns insufficient checks when emulating long jumps, calls or returns.

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GitHub Enterprise 2.0.0 Fixes Multiple Vulnerabilities

Recently we had the pleasure to take a look at GitHub’s Enterprise appliance. The appliance allows one to deploy the excellent GitHub web interface locally to host code on-site. Besides the well known interface, which is similar to the one hosted at, the appliance ships with a separate interface called the management console, which is used for administrative tasks like the configuration of the appliance itself. This management interface is completely decoupled from the user interface.

During our assessment we focused on the management console where we found several vulnerabilities (others may have found them, too). On November 11, 2014 GitHub released a security advisory which included the most critical findings that have been fixed in GitHub Enterprise 2.0.0. Because the advisory doesn’t include any detailed information, we will discuss some of those vulnerabilities in detail.

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How to Own a Router – Fritz!Box AVM Vulnerability Analysis

The below post was originally written on February 9th as a little educational exercise & follow-up to my BinDiff post. (This research was actually triggered by a relative asking about that strange Fritz!Box vulnerability he heard about on the radio). Once we realized the full potential of the bug we decided against publishing the post and contacted several parties instead. Amongst others this contributed to the German BSI press release. Given the cat is out of the bag now anyway, we see no reason to hold it back. We will further take this as an opportunity to lay out our basic vulnerability disclosure principles in a future post. This topic will also be discussed in the panel “Ethics of Security Work & Research” at Troopers


Fritz!Box is series of DSL and WLAN routers produced by AVM. They are extremely popular in Germany and are the uncontested market leader for private DSL customers. Recently, a significant number of Fritz!Box owners became victim of an attack that resulted in calls to expensive international numbers. The newspaper “Der Westen” reported about a case where phone calls valued over 4200€ were initiated from a compromised Fritz!Box.  Few days later AVM published a security update for a large number of Fritz!Box models and urged customers to apply the patch as soon as possible.

However, no further details about the vulnerability were published. This blog post describes our analysis of the vulnerability that we performed directly after the first updates were released.

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