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Security Leftovers

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  • DNS configuration recommendations for IPFire users

    If you are familiar with IPFire, you might have noticed DNSSEC validation is mandatory, since it defeats entire classes of attacks. We receive questions like "where is the switch to turn off DNSSEC" on a regular basis, and to say it once and for all: There is none, and there will never be one. If you are running IPFire, you will be validating DNSSEC. Period.

    Another question frequently asked is why IPFire does not support filtering DNS replies for certain FQDNs, commonly referred to as a Response Policy Zone (RPZ). This is because an RPZ does what DNSSEC attempts to secure users against: Tamper with DNS responses. From the perspective of a DNSSEC-validating system, a RPZ will just look like an attacker (if the queried FQDN is DNSSEC-signed, which is what we strive for as much of them as possible), thus creating a considerable amount of background noise. Obviously, this makes detecting ongoing attacks very hard, most times even impossible - the haystack to search just becomes too big.

    Further, it does not cover direct connections to hardcoded IP addresses, which is what some devices and attackers usually do, as it does not rely on DNS to be operational and does not leave any traces. Using an RPZ will not make your network more secure, it just attempts to cover up the fact that certain devices within it cannot be trusted.

    Back to DNSSEC: In case the queried FQDNs are signed, forged DNS replies are detected since they do not match the RRSIG records retrieved for that domain. Instead of being transparently redirected to a fradulent web server, the client will only display a error message to its user, indicating a DNS lookup failure. Large-scale attacks by returning forged DNS replies are frequently observed in the wild (the DNSChanger trojan is a well-known example), which is why you want to benefit from validating DNSSEC and more and more domains being signed with it.

  • Security updates for Tuesday

    Security updates have been issued by Debian (libx11, webkit2gtk, and zabbix), Fedora (webkit2gtk3), openSUSE (claws-mail, ghostscript, and targetcli-fb), Red Hat (dbus, kpatch-patch, postgresql-jdbc, and python-pillow), Scientific Linux (libvncserver and postgresql-jdbc), SUSE (kernel and python-rtslib-fb), and Ubuntu (ghostscript, sqlite3, squid3, and webkit2gtk). 

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  • Official 1Password Linux App is Available for Testing

    An official 1Password Linux app is on the way, and brave testers are invited to try an early development preview.

    1Password is a user-friendly (and rather popular) cross-platform password manager. It provides mobile apps and browser extensions for Windows, macOS, Android, iOS, Google Chrome, Edge, Firefox — and now a dedicated desktop app for Linux, too.

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  • FBI Warns of Increased DDoS Attacks

    The Federal Bureau of Investigation warned in a “private industry notification” last week that attackers are increasingly using amplification techniques in distributed denial-of-service attacks. There has been an uptick in attack attempts since February, the agency’s Cyber Division said in the alert.
    An amplification attack occurs when attackers send a small number of requests to a server and the server responds with numerous responses. The attackers spoof the IP address to make it look like the requests are coming from a specific victim, and the resulting responses overwhelms the victim’s network.

    “Cyber actors have exploited built-in network protocols, designed to reduce computation overhead of day-to-day system and operational functions to conduct larger and more destructive distributed denial-of-service amplification attacks against US networks,” the FBI alert said. Copies of the alert were posted online by several recipients, including threat intelligence company Bad Packets.

  • NSA issues BootHole mitigation guidance

    Following the disclosure of a widespread buffer-flow vulnerability that could affect potentially billions of Linux and Windows-based devices, the National Security Agency issued a follow-up cybersecurity advisory highlighting the bug and offering steps for mitigation.

    The vulnerability -- dubbed BootHole -- impacts devices and operating systems that use signed versions of the open-source GRUB2 bootloader software found in most Linux systems. It also affects any system or device using Secure Boot -- a root firmware interface responsible for validating the booting process -- with Microsoft's standard third party certificate authority. The vulnerability enables attackers to bypass Secure Boot to allow arbitrary code execution and “could be used to install persistent and stealthy bootkits,” NSA said in a press statement.

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