Last week I wrote about Linux developers evaluating a new "DOITM" security mitigation for the latest Intel CPUs. While the cost for now of engaging the Data Operand Independent Timing Mode (DOITM) functionality is minimal, following internal Intel engineering discussions it looks like the Linux kernel patches will need to be re-worked with this functionality not intended to always be enabled. . As summed up in last week's testing article, recent and future Intel processors aren't guaranteed to be "constant time" with respect to their data operands unless a special model specific register flag is set. This caused concerns particularly around the cryptography code for Linux that there is no longer a guarantee of constant time and that the instruction execution time can vary depending upon the data operated on. The constant time execution is necessary to avoid possible side channel attacks. But in enabling the new Intel flag to ensure constant time, it comes with admitted performance implications. The performance implications with current generation processors didn't end up being all that significant, but Intel documentation indicates that could increase in the future. With the Linux handling in it's current form is about always having the Data Operand Independent Timing Mode enabled. But now Intel is warning against such a move. The link for this article located at Phoronix is no longer available. . The DOITM security function by Intel demands careful analysis since Linux updates necessitate modifications to guarantee both security and operational efficiency.. Intel Timing Mode,Linux Kernel Patch,DOITM Security Feature,Side Channel Attack. . LinuxSecurity.com Team
A recent research paper by a team at University of California, Riverside, shows the existence of previously overlooked side channels in the Linux kernels that can be exploited to attack DNS servers . According to the researchers, the issue with DNS roots in its design, that never really took security as a key concern and that made it extremely hard to retrofit strong security features into it. . While DNS security features are available, including DNSSEC and DNS cookies, they are not widely deployed due to backward compatibility, say the researchers. Instead, the only approach to make DNS more secure has been the randomization of UDP ports, known as ephemeral ports, with the aim to makes it harder for an attacker to discover them. As a result of this, several attacks to DNS have been discovered in the past, including the recent SAD DNS , a variant of DNS cache poisoning that allows an attacker to inject malicious DNS records into a DNS cache, thus redirecting any traffic to their own server and becoming a man-in-the-middle (MITM). . Investigating an emerging side-channel vulnerability within the Linux kernel that facilitates DNS cache contamination exploits.. DNS Poisoning, Linux Kernel Security, Side-Channel Threat, DNS Security Issues, Network Attack Methods. . Brittany Day
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