Tag: heap

更新 Sudo (CVE-2021-3156)

Sudo 這次的安全性漏洞頗痛的：「CVE-2021-3156: Heap-Based Buffer Overflow in Sudo (Baron Samedit)」。

依照 Sudo Security Alerts 這邊的說明，這次的漏洞只要是本機有執行權限的人都有機會打穿，不需要有 sudo 帳號權限：

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。

該來把一堆機器更新了...

繞過 Screensaver Lock 的有趣話題...

在 Hacker News Daily 上看到「Screensaver lock by-pass via the virtual keyboard」這篇，裡面這邊題到了 screensaver lock 的有趣話題。

先講嚴肅一點的，這個 bug 被編號為 CVE-2020-25712，問題出在 xorg-x11-server 上：

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.

小朋友超強 XDDD