Friday, November 15th, 2019

Time	Event
1:10p	Cook: Security things in Linux v5.3 Kees Cook catches up with the security improvements in the 5.3 kernel. "In recent exploits, one of the steps for making the attacker’s life easier is to disable CPU protections like Supervisor Mode Access (and Execute) Prevention (SMAP and SMEP) by finding a way to write to CPU control registers to disable these features. For example, CR4 controls SMAP and SMEP, where disabling those would let an attacker access and execute userspace memory from kernel code again, opening up the attack to much greater flexibility. CR0 controls Write Protect (WP), which when disabled would allow an attacker to write to read-only memory like the kernel code itself. Attacks have been using the kernel’s CR4 and CR0 writing functions to make these changes (since it’s easier to gain that level of execute control), but now the kernel will attempt to 'pin' sensitive bits in CR4 and CR0 to avoid them getting disabled. This forces attacks to do more work to enact such register changes going forward." (Comment on this)
2:42p	Security updates for Friday Security updates have been issued by CentOS (kernel), Debian (ghostscript, mesa, and postgresql-common), Fedora (chromium, php-robrichards-xmlseclibs, php-robrichards-xmlseclibs3, samba, scap-security-guide, and wpa_supplicant), Mageia (cpio, fribidi, libapreq2, python-numpy, webkit2, and zeromq), openSUSE (ImageMagick, kernel, libtomcrypt, qemu, ucode-intel, and xen), Oracle (kernel), Red Hat (ghostscript, kernel, and kernel-rt), Scientific Linux (ghostscript and kernel), SUSE (bash, enigmail, ghostscript, ImageMagick, kernel, libjpeg-turbo, openconnect, and squid), and Ubuntu (ghostscript, imagemagick, and postgresql-common). (Comment on this)
7:46p	[$] Keeping memory contents secret One of the many responsibilities of the operating system is to help processes keep secrets from each other. Operating systems often fail in this regard, sometimes due to factors — such as hardware bugs and user-space vulnerabilities — that are beyond their direct control. It is thus unsurprising that there is an increasing level of interest in ways to improve the ability to keep data secret, perhaps even from the operating system itself. The MAP_EXCLUSIVE patch set from Mike Rapoport is one example of the work that is being done in this area; it also shows that the development community has not yet really begun to figure out how this type of feature should work. (Comment on this)

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