security-misc/debian/control

## Copyright (C) 2012 - 2018 ENCRYPTED SUPPORT LP <adrelanos@riseup.net>
## See the file COPYING for copying conditions.

Source: security-misc
Section: misc
Priority: optional
Maintainer: Patrick Schleizer <adrelanos@riseup.net>
Build-Depends: debhelper (>= 12), genmkfile, config-package-dev
Homepage: https://github.com/Whonix/security-misc
Vcs-Browser: https://github.com/Whonix/security-misc
Vcs-Git: https://github.com/Whonix/security-misc.git
Standards-Version: 4.3.0

Package: security-misc
Architecture: all
Depends: python, libglib2.0-bin, ${misc:Depends}
Replaces: tcp-timestamps-disable
Description: enhances misc security settings
 The following settings are changed:
 .
 deactivates previews in Dolphin;
 deactivates previews in Nautilus;
 deactivates thumbnails in Thunar;
 deactivates TCP timestamps;
 deactivates Netfilter's connection tracking helper;
 implements some kernel hardening;
 prevents DMA attacks;
 .
 TCP time stamps (RFC 1323) allow for tracking clock
 information with millisecond resolution. This may or may not allow an
 attacker to learn information about the system clock at such
 a resolution, depending on various issues such as network lag.
 This information is available to anyone who monitors the network
 somewhere between the attacked system and the destination server.
 It may allow an attacker to find out how long a given
 system has been running, and to distinguish several
 systems running behind NAT and using the same IP address. It might
 also allow one to look for clocks that match an expected value to find the
 public IP used by a user.
 .
 Hence, this package disables this feature by shipping the
 /etc/sysctl.d/tcp_timestamps.conf configuration file.
 .
 Note that TCP time stamps normally have some usefulness. They are
 needed for:
 .
 * the TCP protection against wrapped sequence numbers; however, to
   trigger a wrap, one needs to send roughly 2^32 packets in one
   minute:  as said in RFC 1700, "The current recommended default
   time to live (TTL) for the Internet Protocol (IP) [45,105] is 64".
   So, this probably won't be a practical problem in the context
   of Anonymity Distributions.
 .
 * "Round-Trip Time Measurement", which is only useful when the user
   manages to saturate their connection. When using Anonymity Distributions,
   probably the limiting factor for transmission speed is rarely the capacity
   of the user connection.
 .
 Netfilter's connection tracking helper module increases kernel attack
 surface by enabling superfluous functionality such as IRC parsing in
 the kernel. (!)
 .
 Hence, this package disables this feature by shipping the
 /etc/modprobe.d/30_nf_conntrack_helper_disable.conf configuration file.
 .
 Kernel symbols in /proc/kallsyms are hidden to prevent malware from
 reading them and using them to learn more about what to attack on your system.
 .
 Kexec is disabled as it can be used for live patching of the running kernel.
 .
 The BPF JIT compiler is restricted to the root user and is hardened.
 .
 ASLR effectiveness for mmap is increased.
 .
 The ptrace system call is restricted to the root user only.
 .
 The TCP/IP stack is hardened.
 .
 This package makes some data spoofing attacks harder.
 .
 SACK is disabled as it is commonly exploited and is rarely used.
 .
 This package disables the merging of slabs of similar sizes to prevent an
 attacker from exploiting them.
 .
 Sanity checks, redzoning, and memory poisoning are enabled.
 .
 The kernel now panics on uncorrectable errors in ECC memory which could
 be exploited.
 .
 Kernel Page Table Isolation is enabled to mitigate Meltdown and increase
 KASLR effectiveness.
 .
 SMT is disabled as it can be used to exploit the MDS vulnerability.
 .
 All mitigations for the MDS vulnerability are enabled.
 .
 DCCP, SCTP, TIPC and RDS are blacklisted as they are rarely used and may have
 unknown vulnerabilities.
 .
 The kernel logs are restricted to root only.
 .
 A systemd service clears System.map on boot as these contain kernel symbols
 that could be useful to an attacker.
 .
 The SysRq key is restricted to only allow shutdowns/reboots.
 .
 The thunderbolt and firewire modules are blacklisted as they can be used for
 DMA (Direct Memory Access) attacks.
 .
 IOMMU is enabled with a boot parameter to prevent DMA attacks.
 .
 Coredumps are disabled as they may contain important information such as
 encryption keys or passwords.
 .
 A systemd service mounts /proc with hidepid=2 at boot to prevent users from
 seeing each other's processes.
 .
 The default umask is changed to 006. This allows only the owner and group to read
 and write to newly created files.