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Uninformed Journal (10 unread)

May 09, 2008
1:53
An Objective Analysis of the Lockdown Protection System for Battle.net
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Near the end of 2006, Blizzard deployed the first major update to the version check and client software authentication system used to verify the authenticity of clients connecting to Battle.net using the binary game client protocol. This system had been in use since just after the release of the original Diablo game and the public launch of Battle.net. The new authentication module (Lockdown) introduced a variety of mechanisms designed to raise the bar with respect to spoofing a game client when logging on to Battle.net. In addition, the new authentication module also introduced run-time integrity checks of client binaries in memory. This is meant to provide simple detection of many client modifications (often labeled "hacks") that patch game code in-memory in order to modify game behavior. The Lockdown authentication module also introduced some anti-debugging techniques that are designed to make it more difficult to reverse engineer the module. In addition, several checks that are designed to make it difficult to simply load and run the Blizzard Lockdown module from the context of an unauthorized, non-Blizzard-game process. After all, if an attacker can simply load and run the Lockdown module in his or her own process, it becomes trivially easy to spoof the game client logon process, or to allow a modified game client to log on to Battle.net successfully. However, like any protection mechanism, the new Lockdown module is not without its flaws, some of which are discussed in detail in this paper.
1:53
ActiveX - Active Exploitation
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This paper provides a general introduction to the topic of understanding software vulnerabilities that affect ActiveX controls. A brief description of how ActiveX controls are exposed to Internet Explorer is given along with an analysis of three example ActiveX vulnerabilities that have been previously disclosed.
1:53
Context-keyed Payload Encoding
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A common goal of payload encoders is to evade a third-party detection mechanism which is actively observing attack traffic somewhere along the route from an attacker to their target, filtering on commonly used payload instructions. The use of a payload encoder may be easily detected and blocked as well as opening up the opportunity for the payload to be decoded for further analysis. Even so-called keyed encoders utilize easily observable, recoverable, or guessable key values in their encoding algorithm, thus making decoding on-the-fly trivial once the encoding algorithm is identified. It is feasible that an active observer may make use of the inherent functionality of the decoder stub to decode the payload of a suspected exploit in order to inspect the contents of that payload and make a control decision about the network traffic. This paper presents a new method of keying an encoder which is based entirely on contextual information that is predictable or known about the target by the attacker and constructible or recoverable by the decoder stub when executed at the target. An active observer of the attack traffic however should be unable to decode the payload due to lack of the contextual keying information.
1:53
Improving Software Security Analysis using Exploitation Properties
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Reliable exploitation of security vulnerabilities has continued to become more difficult as formidable mitigations have been established and are now included by default with most modern operating systems. Future exploitation of software vulnerabilities will rely on either discovering ways to circumvent these mitigations or uncovering flaws that are not adequately protected. Since the majority of the mitigations that exist today lack universal bypass techniques, it has become more fruitful to take the latter approach. It is in this vein that this paper introduces the concept of exploitation properties and describes how they can be used to better understand the exploitability of a system irrespective of a particular vulnerability. Perceived exploitability is of utmost importance to both an attacker and to a defender given the presence of modern mitigations. The ANI vulnerability (MS07-017) is used to help illustrate these points by acting as a simple example of a vulnerability that may have been more easily identified as code that should have received additional scrutiny by taking exploitation properties into consideration.
1:53
Real-time Steganography with RTP
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Real-time Transfer Protocol (RTP) is used by nearly all Voice-over-IP systems to provide the audio channel for calls. As such, it provides ample opportunity for the creation of a covert communication channel due to its very nature. While use of steganographic techniques with various audio cover-medium has been extensively researched, most applications of such have been limited to audio cover-medium of a static nature such as WAV or MP3 file audio data. This paper details a common technique for the use of steganography with audio data cover-medium, outlines the problem issues that arise when attempting to use such techniques to establish a full-duplex communications channel within audio data transmitted via an unreliable streaming protocol, and documents solutions to these problems. An implementation of the ideas discussed entitled SteganRTP is included in the reference materials.
1:53
PatchGuard Reloaded: A Brief Analysis of PatchGuard Version 3
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Since the publication of previous bypass or circumvention techniques for Kernel Patch Protection (otherwise known as ``PatchGuard''), Microsoft has continued to refine their patch protection system in an attempt to foil known bypass mechanisms. With the release of Windows Server 2008 Beta 3, and later a full-blown distribution of PatchGuard to Windows Vista / Windows Server 2003 via Windows Update, Microsoft has introduced the next generation of PatchGuard to the general public (``PatchGuard 3''). As with previous updates to PatchGuard, version three represents a set of incremental changes that are designed to address perceived weaknesses and known bypass vectors in earlier versions. Additionally, PatchGuard 3 expands the set of kernel variables that are protected from unauthorized modification, eliminating several mechanisms that might be used to circumvent PatchGuard while co-existing (as opposed to disabling) it. This article describes some of the changes that have been made in PatchGuard 3. This article also proposes several new techniques that can be used to circumvent PatchGuard's defenses. Countermeasures for these techniques are also discussed.
1:53
Getting out of Jail: Escaping Internet Explorer Protected Mode
» ‎ Uninformed Journal

With the introduction of Windows Vista, Microsoft has added a new form of mandatory access control to the core operating system. Internally known as "integrity levels", this new addition to the security manager allows security controls to be placed on a per-process basis. This is different from the traditional model of per-user security controls used in all prior versions of Windows NT. In this manner, integrity levels are essentially a bolt-on to the existing Windows NT security architecture. While the idea is theoretically sound, there does exist a great possibility for implementation errors with respect to how integrity levels work in practice. Integrity levels are the core of Internet Explorer Protected Mode, a new "low-rights" mode where Internet Explorer runs without permission to modify most files or registry keys. This places both Internet Explorer and integrity levels as a whole at the forefront of the computer security battle with respect to Windows Vista.
1:53
OS X Kernel-mode Exploitation in a Weekend
» ‎ Uninformed Journal

Apple's Mac OS X operating system is attracting more attention from users and security researchers alike. Despite this increased interest, there is still an apparent lack of detailed vulnerability development information for OS X. This paper will attempt to help bridge this gap by walking through the entire vulnerability development process. This process starts with vulnerability discovery and ultimately finished with a remote code execution. To help illustrate this process, a real vulnerability found in the OS X wireless device driver is used.
1:53
A Catalog of Local Windows Kernel-mode Backdoor Techniques
» ‎ Uninformed Journal

This paper presents a detailed catalog of techniques that can be used to create local kernel-mode backdoors on Windows. These techniques include function trampolines, descriptor table hooks, model-specific register hooks, page table modifications, as well as others that have not previously been described. The majority of these techniques have been publicly known far in advance of this paper. However, at the time of this writing, there appears to be no detailed single point of reference for many of them. The intention of this paper is to provide a solid understanding on the subject of local kernel-mode backdoors. This understanding is necessary in order to encourage the thoughtful discussion of potential countermeasures and perceived advancements. In the vein of countermeasures, some additional thoughts are given to the common misconception that PatchGuard, in its current design, can be used to prevent kernel-mode rootkits.
1:53
Generalizing Data Flow Information
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Generalizing information is a common method of reducing the quantity of data that must be considered during analysis. This fact has been plainly illustrated in relation to static data flow analysis where previous research has described algorithms that can be used to generalize data flow information. These generalizations have helped support more optimal data flow analysis in certain situations. In the same vein, this paper describes a process that can be employed to generalize and persist data flow information along multiple generalization tiers. Each generalization tier is meant to describe the data flow behaviors of a conceptual software element such as an instruction, a basic block, a procedure, a data type, and so on. This process makes use of algorithms described in previous literature to support the generalization of data flow information. To illustrate the usefulness of the generalization process, this paper also presents an algorithm that can be used to determine reachability at each generalization tier. The algorithm determines reachability starting from the least specific generalization tier and uses the set of reachable paths found to progressively qualify data flow information for each successive generalization tier. This helps to constrain the amount of data flow information that must be considered to a minimal subset.

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Uninformed Journal (10 unread)