幹壞事是進步最大的原動力
這次的漏洞是在打 CTF (capture the flag) 的時候發現的，這個安全漏洞已經被給 CVE 編號並且修正了：「CVE-2019-11043」，回報者與官方的討論可以在「Sec Bug #78599 env_path_info underflow in fpm_main.c can lead to RCE」這邊看到。從回報的標題可以知道這次頗熱鬧的原因，是因為這次有機會 RCE (remote code execution)...
在「PHuiP-FPizdaM」這邊可以看到比較系統性的整理 (以及 exploit)，看起來雖然有不少條件，但都不算太特別的指令，如果以全世界的機器來看，應該會有不少機器中獎...
前幾天寫的「APT 不使用 HTTPS 的說明」的當下就已經有看到在講這個漏洞，但沒讀完就一直放著沒寫：「Remote Code Execution in apt/apt-get」。
漏洞出在實作上的問題，對於 HTTP 重導的程式碼沒有處理好外部字串，在還沒修正的機器上用這個指令關閉 redirect，避免在修正的過程反而被 RCE 打進去：
sudo apt update -o Acquire::http::AllowRedirect=false sudo apt upgrade -o Acquire::http::AllowRedirect=false
但也不是 HTTPS 就能避免這個問題，因為 HTTPS 連線用的程式碼又是另外一份，裡面不知道有沒有問題 (像是之前經典的 Heartbleed)，所以應該還是會繼續爭吵吧...
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...
Google 這次出手炸的好痛：「Behind the Masq: Yet more DNS, and DHCP, vulnerabilities」。
當需要在 client 端處理 DNS 的事情，有蠻多開發者都會選擇用 Dnsmasq 處理，這次直接拉出七個 CVE (編號 CVE-2017-13704 與 CVE-2016-{14491-14496})，其中三個是 RCE：
看了一下，Ubuntu 也推出更新了，接下來有一堆機器要升級 Dnsmasq... :o
在「About the security content of iOS 10.3.1」這邊的說明：
Available for: iPhone 5 and later, iPad 4th generation and later, iPod touch 6th generation and later
Impact: An attacker within range may be able to execute arbitrary code on the Wi-Fi chip
Description: A stack buffer overflow was addressed through improved input validation.
CVE-2017-6975: Gal Beniamini of Google Project Zero
這描述看起來就不太妙...
包含 MySQL 本家與所有從 MySQL 改出去的分支都中了，引用 Percona 的通報：「Percona Server Critical Update CVE-2016-6662」。
This is a CRITICAL update, and the fix mitigates the potential for remote root code execution.
原始的 security advisory 在「CVE-2016-6662 - MySQL Remote Root Code Execution / Privilege Escalation ( 0day )」這邊，雖然是標 0day，但發現的人在七月時就有先通報給 vendor 們讓他們有時間修正：
The vulnerability was reported to Oracle on 29th of July 2016 and triaged by the security team. It was also reported to the other affected vendors including PerconaDB and MariaDB.
Oracle 還沒修正，也就是 upstream 目前仍然是有問題的，目前得靠其他 vendor 修正：
Official patches for the vulnerability are not available at this time for Oracle MySQL server.
其中 Percona 與 MariaDB 都已經先推出修正版本了：
The vulnerabilities were patched by PerconaDB and MariaDB vendors by the end of 30th of August.
然後看了一下這個漏洞，從 SQL 指令可以做檔案操作一路打出來... 可以看到範例：
mysql> set global general_log_file = '/etc/my.cnf';
mysql> set global general_log = on;
mysql> select '
'>
'> ; injected config entry
'>
'> [mysqld]
'> malloc_lib=/tmp/mysql_exploit_lib.so
'>
'> [separator]
'>
'> ';
1 row in set (0.00 sec)
mysql> set global general_log = off;這下苦了...
NSA 使用這些漏洞來大量監聽企業的流量：「Leaked Exploits are Legit and Belong to NSA: Cisco, Fortinet and Snowden Docs Confirm」。
Cisco 已經確認這個安全性漏洞了，全系列包括已經停產的 Cisco PIX、上個世代的 Cisco ASA 5500 (但還有些型號還在賣)，以及目前主力的 Cisco ASA 5500-X，另外還包括了安全模組系列也中獎：「Cisco Adaptive Security Appliance SNMP Remote Code Execution Vulnerability」。
標星號的是目前已經沒有在維護的產品，這次只確認受到影響，但不會更新：
Cisco Firewall Service Modules and Cisco PIX Firewalls have passed the last day of software support milestone as stated in the published End of Life (EoL) documents. Further investigations into these devices will not be performed, and fixed software will not be made available.
這次 Cisco 的安全性問題是 SNMP 的洞造成的：
Administrators are advised to allow only trusted users to have SNMP access and to monitor affected systems using the snmp-server host command.
這個洞被 NSA 用來寫 exploit 植入系統：
This flaw was included inside two NSA exploits, dubbed EPICBANANA as well as JETPLOW, which is an enhanced version of EPICBANANA, but with better persistence capabilities, Cisco's Omar Santos said in a blog post.
在 NSA 洩漏出來的文件裡可以看到 ace02468bdf13579 這個特殊辨識字串，而在受感染的樣本上也找到了這個痕跡：
而且不只是 Cisco，其他幾家也中獎了，可以參考「The NSA Leak Is Real, Snowden Documents Confirm」這邊更多的資訊 @_@
關於 Samba 與 Windows 網芳的安全性問題，拖了三個禮拜的「Badlock Bug」的細節總算公佈了 (網頁還不支援 HTTPS)。
果然是為了打名氣而事前公佈的... 都不是無條件的 RCE (Remote Code Execution)，而是透過 MITM 後的 RCE。
在「Remote Code Execution in all git versions (client + server) < 2.7.1: CVE-2016-2324, CVE-2016‑2315」這邊看到歡樂的 CVE-2016-2315 與 CVE-2016-2324，屬於 RCE 類漏洞。
Git 2.7.1 之前的所有版本都有問題，看起來由於問題過於大條，在 2016/02/06 發表的「Git v2.7.1 Release Notes」沒有標出這兩個 CVE，讓所有 vendor 有時間升級。
不過看起來 GitLab 不在被通知的 vendor 裡面，很無奈的在 CVE 公開後馬上推出新版，需要升級到最新版本：「GitLab 8.5.7 Released」。
Google 寫了一篇關於 CVE-2015-7547 的安全性問題：「CVE-2015-7547: glibc getaddrinfo stack-based buffer overflow」。
Google 的工程師在找 OpenSSH 連到某台特定主機就會 segfault 的通靈過程中，發現問題不在 OpenSSH，而是在更底層的 glibc 導致 segfault：
Recently a Google engineer noticed that their SSH client segfaulted every time they tried to connect to a specific host. That engineer filed a ticket to investigate the behavior and after an intense investigation we discovered the issue lay in glibc and not in SSH as we were expecting.
由於等級到了 glibc 這種每台 Linux 都有裝的情況，在不經意的情況下發生 segfault，表示在刻意攻擊的情況下可能會很糟糕，所以 Google 投入了人力研究，想知道這個漏洞到底可以做到什麼程度：
Thanks to this engineer’s keen observation, we were able determine that the issue could result in remote code execution. We immediately began an in-depth analysis of the issue to determine whether it could be exploited, and possible fixes. We saw this as a challenge, and after some intense hacking sessions, we were able to craft a full working exploit!
在研究過程中 Google 發現 Red Hat 的人也在研究同樣的問題：「(CVE-2015-7547) - In send_dg, the recvfrom function is NOT always using the buffer size of a newly created buffer (CVE-2015-7547)」：
In the course of our investigation, and to our surprise, we learned that the glibc maintainers had previously been alerted of the issue via their bug tracker in July, 2015. (bug). We couldn't immediately tell whether the bug fix was underway, so we worked hard to make sure we understood the issue and then reached out to the glibc maintainers. To our delight, Florian Weimer and Carlos O’Donell of Red Hat had also been studying the bug’s impact, albeit completely independently! Due to the sensitive nature of the issue, the investigation, patch creation, and regression tests performed primarily by Florian and Carlos had continued “off-bug.”
攻擊本身需要繞過反制機制 (像是 ASLR)，但仍然是可行的，Google 的人已經成功寫出 exploit code：
Remote code execution is possible, but not straightforward. It requires bypassing the security mitigations present on the system, such as ASLR. We will not release our exploit code, but a non-weaponized Proof of Concept has been made available simultaneously with this blog post.
技術細節在 Google 的文章裡也有提到，buffer 大小固定為 2048 bytes，但取得時有可能超過 2048 bytes，於是造成 buffer overflow：
glibc reserves 2048 bytes in the stack through alloca() for the DNS answer at _nss_dns_gethostbyname4_r() for hosting responses to a DNS query.
Later on, at send_dg() and send_vc(), if the response is larger than 2048 bytes, a new buffer is allocated from the heap and all the information (buffer pointer, new buffer size and response size) is updated.
另外 glibc 官方的 mailing list 上也有說明：「[PATCH] CVE-2015-7547 --- glibc getaddrinfo() stack-based buffer overflow」。