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Imgur 也漏資料了... (帳號與密碼)

Imgur 官方發佈公告說明他們發現資料洩漏了:「Notice of Data Breach」,資料的洩漏是發生在 2014 年,包括了帳號與密碼:

Early morning on November 24th, we confirmed that approximately 1.7 million Imgur user accounts were compromised in 2014. The compromised account information included only email addresses and passwords. Imgur has never asked for real names, addresses, phone numbers, or other personally-identifying information (“PII”), so the information that was compromised did NOT include such PII.

然後 2014 年用的是 SHA-256

We have always encrypted your password in our database, but it may have been cracked with brute force due to an older hashing algorithm (SHA-256) that was used at the time. We updated our algorithm to the new bcrypt algorithm last year.

以單台八張 GTX 1080hashcat 的速度來看 (出自「8x Nvidia GTX 1080 Hashcat Benchmarks」),是 23GH/z 左右:

Hashtype: SHA256

Speed.Dev.#1.: 2865.2 MH/s (96.18ms)
Speed.Dev.#2.: 2839.8 MH/s (96.65ms)
Speed.Dev.#3.: 2879.5 MH/s (97.14ms)
Speed.Dev.#4.: 2870.6 MH/s (96.32ms)
Speed.Dev.#5.: 2894.2 MH/s (96.64ms)
Speed.Dev.#6.: 2857.7 MH/s (96.78ms)
Speed.Dev.#7.: 2899.3 MH/s (96.46ms)
Speed.Dev.#8.: 2905.7 MH/s (96.26ms)
Speed.Dev.#*.: 23012.1 MH/s

這對於鍵盤可以打出的所有字元來計算 (95 chars),八個字的密碼只要 3.33 天就可以跑完;如果只考慮英文數字 (62 chars),九個字的密碼只要 6.81 天。

這些還不是最新的 GPU,而且是單機計算,對於現在的攻擊應該會用 ASIC,可以考慮多三到四個數量級的數度在算 (看財力才會知道買多少機器)。

不過 Imgur 的帳號主要是參與討論 (因為不用帳號密碼也可以上傳圖片),一般比較不會在上面註冊... 真的有註冊的因為沒有其他個資,主要是怕共用密碼的問題。如果有用 password manager 應該也還好。

以色列黑了 Kaspersky 的系統,然後通報美國機密資料外洩...

前幾天在「俄羅斯政府透過卡巴斯基的漏洞,偷取美國國安局的文件」這邊提到了俄羅斯是透過 Kaspersky 的漏洞取得,後續又有些消息揭露出來了...

這件事情會被抓包,是因為以色列黑進去 Kaspersky 的系統 (???),然後發現美國的機密資料外洩 (??????),於是通報盟友美國後追查出來的 (?????????):「Israel hacked Kaspersky, then tipped the NSA that its tools had been breached」。

這過程是殺小 XDDD

Yahoo! 的資料外洩數量超過之前公佈的十億筆,上升到三十億筆

Oath (Y! 的新東家,Verizon 持股) 發表了新的通報,外洩數量直接上升到 3 billion 了:「Yahoo provides notice to additional users affected by previously disclosed 2013 data theft」。

也就是當時所有的使用者都受到影響:

Subsequent to Yahoo's acquisition by Verizon, and during integration, the company recently obtained new intelligence and now believes, following an investigation with the assistance of outside forensic experts, that all Yahoo user accounts were affected by the August 2013 theft.

在「Yahoo says all 3 billion user accounts were impacted by 2013 security breach」這邊的報導則是寫的比較清楚,把當時的使用者數字翻出來:

Yahoo today announced that the huge data breach in August 2013 affected every user on its service — that’s all three billion user accounts and up from the initial one billion figure Yahoo initially reported.

2013 這包用的是 MD5 hash,以現在的運算能力來看,可以當作沒有 hash...:

The stolen user account information may have included names, email addresses, telephone numbers, dates of birth, hashed passwords (using MD5) and, in some cases, encrypted or unencrypted security questions and answers.

已經是 "all" 了,接下來要更大包只能是其他主題了...

Apache 的 Optionsbleed

Apache 也出了類似 Heartbleed 的包:「Apache bug leaks contents of server memory for all to see—Patch now」,原文出自「Optionsbleed - HTTP OPTIONS method can leak Apache's server memory」。

這掛上 CVE-2017-9798 了,影響版本包括了:

This affects the Apache HTTP Server through 2.2.34 and 2.4.x through 2.4.27.

發生在對 OPTIONS 處理出問題:

Optionsbleed is a use after free error in Apache HTTP that causes a corrupted Allow header to be constructed in response to HTTP OPTIONS requests. This can leak pieces of arbitrary memory from the server process that may contain secrets. The memory pieces change after multiple requests, so for a vulnerable host an arbitrary number of memory chunks can be leaked.

就... 更新吧 @_@

最近 OpenVPN 的安全性漏洞...

看到「The OpenVPN post-audit bug bonanza」這個只有苦笑啊...

作者在 OpenVPN 經過一連串的安全加強後 (包括 harden 計畫與兩個外部單位的程式碼稽核找到不少問題),決定出手挖看看:

After a hardening of the OpenVPN code (as commissioned by the Dutch intelligence service AIVD) and two recent audits 1 2, I thought it was now time for some real action ;).

然後就挖出不少問題了...

可以看到作者透過 fuzzing 打出一卡車,包含了不少 crash XDDD:(然後有一個是 stack buffer corruption,不知道有沒有機會變成 RCE)

  • Remote server crashes/double-free/memory leaks in certificate processing (CVE-2017-7521)
  • Remote (including MITM) client crash, data leak (CVE-2017-7520)
  • Remote (including MITM) client stack buffer corruption
  • Remote server crash (forced assertion failure) (CVE-2017-7508)
  • Crash mbed TLS/PolarSSL-based server (CVE-2017-7522)
  • Stack buffer overflow if long –tls-cipher is given

利用 Side-channel 資訊判斷被 HTTPS 保護的 Netflix 影片資訊

在「Netflix found to leak information on HTTPS-protected videos」這篇看到了研究員透過 VBR 所透露出的 side channel 資訊,成功的取得了被 HTTPS 保護的 Netflix 影片資訊。這對於美國的 ISP 是個大利多 (加上之前通過的法案),但對於個人隱私則是嚴重的打擊。

這項研究的準確率非常高:

To support our analysis, we created a fingerprint database comprised of 42,027 Netflix videos. Given this collection of fingerprints, we show that our system can differentiate between videos with greater than 99.99% accuracy. Moreover, when tested against 200 random 20-minute video streams, our system identified 99.5% of the videos with the majority of the identifications occurring less than two and a half minutes into the video stream.

而且他們居然是用這樣的單機分析:

null

苦啊...

Cloudbleed:Cloudflare 這次的安全問題

Cloudflare 把完整的時間軸與影響範圍都列出來了:「Incident report on memory leak caused by Cloudflare parser bug」。

出自於 2/18 時 GoogleTavis Ormandy 直接在 Twitter 上找 Cloudflare 的人:

Google 的 Project Zero 上的資料:「cloudflare: Cloudflare Reverse Proxies are Dumping Uninitialized Memory」。

起因在於 bug 造成有時候會送出不應該送的東西,可能包含了敏感資料:

It turned out that in some unusual circumstances, which I’ll detail below, our edge servers were running past the end of a buffer and returning memory that contained private information such as HTTP cookies, authentication tokens, HTTP POST bodies, and other sensitive data.

不過這邊不包括 SSL 的 key,主要是因為隔離開了:

For the avoidance of doubt, Cloudflare customer SSL private keys were not leaked. Cloudflare has always terminated SSL connections through an isolated instance of NGINX that was not affected by this bug.

不過由於這些敏感資料甚至還被 Google 收進 search engine,算是相當的嚴重,所以不只是 Cloudflare 得修好這個問題,還得跟眾多的 search engine 合作將這些資料移除:

Because of the seriousness of such a bug, a cross-functional team from software engineering, infosec and operations formed in San Francisco and London to fully understand the underlying cause, to understand the effect of the memory leakage, and to work with Google and other search engines to remove any cached HTTP responses.

bug 影響的時間從 2016/09/22 開始:

2016-09-22 Automatic HTTP Rewrites enabled
2017-01-30 Server-Side Excludes migrated to new parser
2017-02-13 Email Obfuscation partially migrated to new parser
2017-02-18 Google reports problem to Cloudflare and leak is stopped

而以 2/13 到 2/18 的流量反推估算,大約是 0.00003% 的 request 會可能產生這樣的問題:

The greatest period of impact was from February 13 and February 18 with around 1 in every 3,300,000 HTTP requests through Cloudflare potentially resulting in memory leakage (that’s about 0.00003% of requests).

不過不得不說 Tavis Ormandy 真的很硬,在沒有 source code 以及 Cloudflare 幫助的情況下直接打出可重製的步驟:

I worked with cloudflare over the weekend to help clean up where I could. I've verified that the original reproduction steps I sent cloudflare no longer work.

事發後完整的時間軸:

2017-02-18 0011 Tweet from Tavis Ormandy asking for Cloudflare contact information
2017-02-18 0032 Cloudflare receives details of bug from Google
2017-02-18 0040 Cross functional team assembles in San Francisco
2017-02-18 0119 Email Obfuscation disabled worldwide
2017-02-18 0122 London team joins
2017-02-18 0424 Automatic HTTPS Rewrites disabled worldwide
2017-02-18 0722 Patch implementing kill switch for cf-html parser deployed worldwide
2017-02-20 2159 SAFE_CHAR fix deployed globally
2017-02-21 1803 Automatic HTTPS Rewrites, Server-Side Excludes and Email Obfuscation re-enabled worldwide

另外在「List of Sites possibly affected by Cloudflare's #Cloudbleed HTTPS Traffic Leak」這邊有人整理出受影響的大站台有哪些 (小站台就沒列上去了)。

Yahoo! 這次應該是史上最大的一次 leak...

Yahoo! 這次爆出來的 leak 應該是目前史上最大的一次:「An Important Message About Yahoo User Security」。

目前 Yahoo! 的研判是 2014 年時由政府單位搬出去的:

A recent investigation by Yahoo has confirmed that a copy of certain user account information was stolen from the company’s network in late 2014 by what it believes is a state-sponsored actor.

這包括了密碼的部份 (受過不同程度的 hash 保護):

The account information may have included names, email addresses, telephone numbers, dates of birth, hashed passwords (the vast majority with bcrypt) and, in some cases, encrypted or unencrypted security questions and answers.

照這樣的用詞,猜測是登入時一直將舊的密碼換掉... 類似於 $2a$ 這樣可以知道編碼方式的機制。

這次洩漏的資料大約有五億筆:

Based on the ongoing investigation, Yahoo believes that information associated with at least 500 million user accounts was stolen and the investigation has found no evidence that the state-sponsored actor is currently in Yahoo’s network. Yahoo is working closely with law enforcement on this matter.

依照目前在「Have I been pwned? Check if your email has been compromised in a data breach」上的資料,最大的應該是 MySpace 的 3.5 億筆,看起來這次會刷記錄...

Dropbox 儲存密碼的方式

記得 Dropbox 前陣子才強迫所有使用者重設密碼:「The Dropbox hack is real」,官方的報告在這:「Resetting passwords to keep your files safe」,當時洩漏出來的資訊可以知道 2012 年的時候 Dropbox 用的是 SHA1:

What we've got here is two files with email address and bcrypt hashes then another two with email addresses and SHA1 hashes.

三個多禮拜候,Dropbox 說明了現在的密碼儲存策略:「How Dropbox securely stores your passwords」,現在是先 SHA512,再 bcrypt,然後存在資料庫裡時使用 AES256 保護:

比較特別一點的是先 SHA512 的部份,除了 72bytes 常見限制外,另外一個原因是為了避免 DoS,不過還是覺得有點怪就是了:

Other implementations don’t truncate the input and are therefore vulnerable to DoS attacks because they allow the input of arbitrarily long passwords.

而 AES256 的部份則是確保就算 SQL injection 或是其他方式將儲存的密碼撈出去後,也還有相當程度的保護能力。

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