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Security: Secure Shell, MasterPeace, “Dark Web Scan” and Reproducible Builds

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Security
  • Secure Shell: What is SSH?

    So, here is my ode to Secure Shell for those that are unaware of SSH (It will not be any kind of artistic prose.) Many outside of the technology world may not realize how oft-utilized and important SSH and, indeed, shelling is in our everyday technological lives. This article will examine SSH and shelling, in general, and go over some of the technical aspects that encompass SSH and secure shell.

  • A Columbia cyber firm’s open source project is looking to improve IoT security

    Columbia-based MasterPeace Solutions is working on an open source project to address security vulnerabilities in Internet of Things devices.

    osMUD is aimed at protecting internet-connected devices used at homes and small businesses. The project was shared with the National Institute of Standards and Technology’s National Cybersecurity Center of Excellence, which is based in Rockville, according to MasterPeace.

    Now, the cybersecurity firm will participate in a consortium that was formed around the effort that looks to bring together bring together device manufacturers, network security companies, and network administrators. Participating organizations include Cable Labs, Cisco, CTIA, Digicert, ForeScout, Global Cyber Alliance, Patton, and Symantec. Each organization will provide code and expertise to the effort. MasterPeace is providing network security engineering and defense operations expertise. The longtime government contractor has previously shown willingness to gather the community in recent years with efforts like an in-house accelerator.

  • What is a “Dark Web Scan” and Should You Use One?

    The “dark web” consists of hidden websites that you can’t access without special software. These websites won’t appear when you use Google or another search engine, and you can’t even access them unless you go out of your way to use the appropriate tools.

    For example, the Tor software can be used for anonymous browsing of the normal web, but it also hides special sites known as “.onion sites” or “Tor hidden services.” These websites use Tor to cloak their location, and you only access them through the Tor network.

  • Reproducible Builds Joins Conservancy

    We are very excited to announce the Reproducible Builds project as our newest member project. Reproducible builds is a set of software development practices that create an independently-verifiable path from the source code to the binary code used by computers. This ensures that the builds you are installing are exactly the ones you were expecting, which is critical for freedom, security and compatibility and exposes injections of backdoors introduced by compromising build servers or coercing developers to do so via political or violent means.

    The Reproducible Builds project, which began as a project within the Debian community, joins our other adjacent work around this distribution, such as the Debian Copyright Aggregation Project. Reproducible Builds is also critical to Conservancy's own compliance work: a build that cannot be verified may contain code that triggers different license compliance responsibilities than those which the recipient is expecting. Unaccounted-for code makes it hard for anyone who distributes software to guarantee that they are doing so responsibly and with care for those who receive the software.

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Kernel: Zinc and 4.20 Merge Window

  • Zinc: a new kernel cryptography API
    We looked at the WireGuard virtual private network (VPN) back in August and noted that it is built on top of a new cryptographic API being developed for the kernel, which is called Zinc. There has been some controversy about Zinc and why a brand new API was needed when the kernel already has an extensive crypto API. A recent talk by lead WireGuard developer Jason Donenfeld at Kernel Recipes 2018 would appear to be a serious attempt to reach out, engage with that question, and explain the what, how, and why of Zinc. WireGuard itself is small and, according to Linus Torvalds, a work of art. Two of its stated objectives are maximal simplicity and high auditability. Donenfeld initially did try to implement WireGuard using the existing kernel cryptography API, but after trying to do so, he found it impossible to do in any sane way. That led him to question whether it was even possible to meet those objectives using the existing API. By way of a case study, he considered big_key.c. This is kernel code that is designed to take a key, store it encrypted on disk, and then return the key to someone asking for it if they are allowed to have access to it. Donenfeld had taken a look at it, and found that the crypto was totally broken. For a start, it used ciphers in Electronic Codebook (ECB) mode, which is known to leave gross structure in ciphertext — the encrypted image of Tux on the left may still contain data perceptible to your eye — and so is not recommended for any serious cryptographic use. Furthermore, according to Donenfeld, it was missing authentication tags (allowing ciphertext to be undetectably modified), it didn't zero keys out of memory after use, and it didn't use its sources of randomness correctly; there were many CVEs associated with it. So he set out to rewrite it using the crypto API, hoping to better learn the API with a view to using it for WireGuard. The first step with the existing API is to allocate an instance of a cipher "object". The syntax for so doing is arguably confusing — for example, you pass the argument CRYPTO_ALG_ASYNC to indicate that you don't want the instance to be asynchronous. When you've got it set up and want to encrypt something, you can't simply pass data by address. You must use scatter/gather to pass it, which in turn means that data in the vmalloc() area or on the stack can't just be encrypted with this API. The key you're using ends up attached not to the object you just allocated, but to the global instance of the algorithm in question, so if you want to set the key you must take a mutex lock before doing so, in order to be sure that someone else isn't changing the key underneath you at the same time. This complexity has an associated resource cost: the memory requirements for a single key can approach a megabyte, and some platforms just can't spare that much. Normally one would use kvalloc() to get around this, but the crypto API doesn't permit it. Although this was eventually addressed, the fix was not trivial.
  • 4.20 Merge window part 2
    At the end of the 4.20 merge window, 12,125 non-merge changesets had been pulled into the mainline kernel repository; 6,390 came in since last week's summary was written. As is often the case, the latter part of the merge window contained a larger portion of cleanups and fixes, but there were a number of new features in the mix as well.

Limiting the power of package installation in Debian

There is always at least a small risk when installing a package for a distribution. By its very nature, package installation is an invasive process; some packages require the ability to make radical changes to the system—changes that users surely would not want other packages to take advantage of. Packages that are made available by distributions are vetted for problems of this sort, though, of course, mistakes can be made. Third-party packages are an even bigger potential problem because they lack this vetting, as was discussed in early October on the debian-devel mailing list. Solutions in this area are not particularly easy, however. Lars Wirzenius brought up the problem: "when a .deb package is installed, upgraded, or removed, the maintainer scripts are run as root and can thus do anything." Maintainer scripts are included in a .deb file to be run before and after installation or removal. As he noted, maintainer scripts for third-party packages (e.g. Skype, Chrome) sometimes add entries to the lists of package sources and signing keys; they do so in order to get security updates to their packages safely, but it may still be surprising or unwanted. Even simple mistakes made in Debian-released packages might contain unwelcome surprises of various sorts. He suggested that there could be a set of "profiles" that describe the kinds of changes that might be made by a package installation. He gave a few different examples, such as a "default" profile that only allowed file installation in /usr, a "kernel" profile that can install in /boot and trigger rebuilds of the initramfs, or "core" that can do anything. Packages would then declare which profile they required. The dpkg command could arrange that package's install scripts could only make the kinds of changes allowed by its profile. Read more

SpamAssassin is back

The SpamAssassin 3.4.2 release was the first from that project in well over three years. At the 2018 Open Source Summit Europe, Giovanni Bechis talked about that release and those that will be coming in the near future. It would seem that, after an extended period of quiet, the SpamAssassin project is back and has rededicated itself to the task of keeping junk out of our inboxes. Bechis started by noting that spam filtering is hard because everybody's spam is different. It varies depending on which languages you speak, what your personal interests are, which social networks you use, and so on. People vary, so results vary; he knows a lot of Gmail users who say that its spam filtering works well, but his Gmail account is full of spam. Since Google knows little about him, it is unable to train itself to properly filter his mail. Just like Gmail, SpamAssassin isn't the perfect filter for everybody right out of the box; it's really a framework that can be used to create that filter. Getting the best out of it can involve spending some time to write rules, for example. Read more