ExpressVPN 在土耳其的 VPN server 被抄...

ExpressVPN 在土耳其的 VPN server 被抄,為了調查大使的刺殺案件:「VPN Server Seized to Investigate Russian Ambassador’s Assassination」。

A VPN server operated by ExpressVPN was seized by Turkish authorities to investigate the assassination of Andrei Karlov, the Russian Ambassador to Turkey. Authorities hoped to find more information on people who removed digital traces of the assassin, but the server in question held no logs.

ExpressVPN 官方的回覆在「ExpressVPN statement on Andrey Karlov investigation」,主要的部份是:

As we stated to Turkish authorities in January 2017, ExpressVPN does not and has never possessed any customer connection logs that would enable us to know which customer was using the specific IPs cited by the investigators. Furthermore, we were unable to see which customers accessed Gmail or Facebook during the time in question, as we do not keep activity logs. We believe that the investigators’ seizure and inspection of the VPN server in question confirmed these points.

至於是不是真的,就需要時間確認了...

WPA2 安全漏洞

話說 WPA2 也撐了十三年了:

WPA2 became available in 2004 and is a common shorthand for the full IEEE 802.11i (or IEEE 802.11i-2004) standard.

這次的漏洞可以參考「Severe flaw in WPA2 protocol leaves Wi-Fi traffic open to eavesdropping」這邊。

PoC 稱作 KRACK (Key Reinstallation Attacks),漏洞將會在十一月正式發表,從會議的標題名稱大概可以知道方向,是對 Nonce 下手:「Key Reinstallation Attacks: Forcing Nonce Reuse in WPA2」。另外站台 www.krackattacks.com 已經放好,等後續的發表更新了。

對於無線網路的各種漏洞,老方法還是目前最有效的方法,也是這次的 workaround 之一:上強度足夠的 VPN。

Update:補上論文「Key Reinstallation Attacks: Forcing Nonce Reuse in WPA2」。

VPN 保留連線記錄幫助 FBI 抓犯人

這應該是這幾天鬧得蠻大的事情:「PureVPN Logs Helped FBI Net Alleged Cyberstalker」。

起因在於 PureVPN 的廣告寫著他們不會記錄:

但在證詞裡卻提到 PureVPN 有記錄:

“Significantly, PureVPN was able to determine that their service was accessed by the same customer from two originating IP addresses: the RCN IP address from the home Lin was living in at the time, and the software company where Lin was employed at the time,” the agent’s affidavit reads.

然後回頭看 PureVPN 的 Privacy 條款發現他們在條款裡面寫著他們會記錄連線資訊:

Our servers automatically record the time at which you connect to any of our servers. From here on forward, we do not keep any records of anything that could associate any specific activity to a specific user. The time when a successful connection is made with our servers is counted as a ‘connection’ and the total bandwidth used during this connection is called ‘bandwidth’. Connection and bandwidth are kept in record to maintain the quality of our service. This helps us understand the flow of traffic to specific servers so we could optimize them better.

然後被告 Ryan S. Lin 就幹剿了:

“There is no such thing as a VPN that doesn’t keep logs,” Lin said. “If they can limit your connections or track bandwidth usage, they keep logs.”

以後挑 VPN 還得仔細看條款裡面留 log 的部份啊...

VPN 的評價

文章的作者試了很多家 VPN 服務,然後文章的標題有點長,有種輕小說的感覺...:「I tested the most recommended VPN providers using my credit card to find the best ones — and which ones you should avoid.」。

不過這種文章有很多東西很主觀,大家心裡有個底就是了...

作者比較滿意的是 TunnelBearOVPN 這兩家,也許等手上 PIA 到期的時候再試看看要怎麼選好了,畢竟 PIA 還是目前最便宜的方案。

在飯店裡攻擊企業的高階主管

算是為什麼企業要提供 Full Routing VPN 的一個攻擊管道的說明...

這篇介紹了在飯店裡透過 WiFi 攻擊企業的高階主管,想辦法塞木馬取得資訊,或是滲透進企業內部的網路:「Hackers are using hotel Wi-Fi to spy on guests, steal data」。

Those behind the campaign have continually evolved their tactics and malware payloads, blending phishing and social engineering with a complex Trojan, in order to conduct espionage on corporate research and development personnel, CEOs, and other high-ranking corporate officials.

有點介於 APT 與一般性的攻擊中間...

Google 推的 BeyondCorp

Google 在推的 BeyondCorp 發了一篇介紹出來:「How to use BeyondCorp to ditch your VPN, improve security and go to the cloud」。

裡面有提到幾篇研究:

在文章開頭處有提到 BeyondCorp 的想法是「zero-trust network security model」,這樣就比較能理解他的設計了:

We moved away from our corporate VPN, and introduced BeyondCorp, a zero-trust network security model.

當掃地的阿桑可以碰到企業內的實體網路時,要怎麼設計防禦機制...

Cisco 與 Fortinet 防火牆的 RCE 漏洞

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」。

  • Cisco ASA 5500 Series Adaptive Security Appliances
  • Cisco ASA 5500-X Series Next-Generation Firewalls
  • Cisco ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers
  • Cisco ASA 1000V Cloud Firewall
  • Cisco Adaptive Security Virtual Appliance (ASAv)
  • Cisco Firepower 4100 Series
  • Cisco Firepower 9300 ASA Security Module
  • Cisco Firepower Threat Defense Software
  • Cisco Firewall Services Module (FWSM)*
  • Cisco Industrial Security Appliance 3000
  • Cisco PIX Firewalls*

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 @_@

Ubuntu 桌機的 Split DNS

Split DNS 指的是某個 DNS domain 使用另外一組 DNS servers,常用在 Partial Route 的 VPN 上,讓內部網域的 DNS domain 正確的被解出來。一般商業的 VPN Software 都會處理掉這塊,不過有時候還是希望可以自己設定...

Ubuntu 桌機上的 Split DNS 可以透過 Dnsmasq 做到,在我的機器上因為透過 ps awx | grep dnsmasq 可以看到 --conf-dir=/etc/NetworkManager/dnsmasq.d,表示設定的目錄在 /etc/NetworkManager/dnsmasq.d 下,所以我把檔案 mysplit 放到 /etc/NetworkManager/dnsmasq.d 下:

#
server=/mysplit.com/10.1.2.3

然後在 dnsmasq 的 manpage 裡面有提到,SIGUSR{1,2} 是拿來分析用的,而 SIGHUP 不是拿來給你重新讀設定檔用的 XDDD

SIGHUP does NOT re-read the configuration file.

所以就砍掉他,隨便對 NetworkManager 做個動作,就會重新把 dnsmasq 帶起來了,或者重開機也可以... 再跑 dig 查的時候就可以查到資訊了。

VPC VPN 的新功能

Amazon VPC 的 VPN 推出新功能了:「EC2 VPC VPN Update – NAT Traversal, Additional Encryption Options, and More」。

其中「Reusable CGW IP Addresses」這個功能讓大家等超久的:(CGW 是 Customer Gateway,通常是放在自己的機房裡跟 Amazon VPC 設 site-to-site VPN 對接)

You no longer need to specify a unique IP address for each customer gateway connection that you create. Instead, you can now reuse an existing IP address. Many VPC users have been asking for this feature and I expect it to be well-used.

之前得弄一堆 IP address 來接來接去,現在總算是改善了...

在攻擊時總是挑最弱的一環:NSA 對 DH 的攻擊

在「How is NSA breaking so much crypto?」這邊提到了 2012 年有文章說明 NSA 有能力解開部份的加密通訊,而後來 Snowden 所提供的資料也證實了這點:

In 2012, James Bamford published an article quoting anonymous former NSA officials stating that the agency had achieved a “computing breakthrough” that gave them “the ability to crack current public encryption.” The Snowden documents also hint at some extraordinary capabilities: they show that NSA has built extensive infrastructure to intercept and decrypt VPN traffic and suggest that the agency can decrypt at least some HTTPS and SSH connections on demand.

但在這之前一直都不清楚是怎麼解出來的,直到最近才猜測應該是 Diffie-Hellman 的強度以及實作問題:「Imperfect Forward Secrecy: How Diffie-Hellman Fails in Practice」。

而成果其實非常驚人,由於強度不夠以及實作問題,有相當可觀的數量是可被攻擊的:

We go on to consider Diffie-Hellman with 768- and 1024-bit groups. We estimate that even in the 1024-bit case, the computations are plausible given nation-state resources. A small number of fixed or standardized groups are used by millions of servers; performing precomputation for a single 1024-bit group would allow passive eavesdropping on 18% of popular HTTPS sites, and a second group would allow decryption of traffic to 66% of IPsec VPNs and 26% of SSH servers. A close reading of published NSA leaks shows that the agency’s attacks on VPNs are consistent with having achieved such a break. We conclude that moving to stronger key exchange methods should be a priority for the Internet community.

作者群給的建議有三個方向,一個是把長度加長到 2048 bits,另外一個是改用 ECDH,而最差的情況 (如果還是需要使用 1024 bits DH) 則是避免使用固定的 prime number。