Pierluigi Paganini
August 30, 2021
The 25 days long DDoS attack against the website of Karapatan was launched by almost 30.000 IP addresses, whereas one third of the addresses originated from devices that there were not running “Open Proxies” or “Tor exits”. Identifying this mysterious part of the botnet turned to be a fascinating research and a digital forensics challenge. The traces lead us to an Israeli firm offering access to millions of proxies in mobile operators, data centers and residential buildings – a perfect infrastructure to hide the source of DDoS attacks.
This is Part II of our ongoing research on the DDoS attack against Karapatan. For background information, please read the report “Human rights alliance ‘Karapatan’ under long lasting DDoS attack“.
Finding patterns – identifying clusters
Once we were able to flag the addresses associated with the Tor network and those that came from publicly visible proxy services, we classified the 8,000 “unknown” IP addresses in pools based on country, operator, time and attack cluster. We defined an “attack cluster” as the group of IP addresses that flooded the website within one hour period with similar requests.
A few patterns showed quickly, the first one was that most of the addresses came from a number of mobile providers in Russia and Ukraine, such as MTS, MegaFon, T2 Mobile, PVimpelCom and Kyivstar.
We also noticed that the IPs were rotating every hour, and blocks of 50 new IPs were launching the same query attack at the same time.
During an attack of this nature, it is difficult to find clear patterns without fast data and log processing and ad-hoc tools but our DNS servers were clearly recording these spikes of DNS updates every time the botnet was renewing IP addresses. We love patterns and here we found a clear one!
The first finding was that the attackers kept using their “CC-Attack modified python script” generating GET and POST floods to the /resources section of karapatan.org but instead of using open proxies and the Tor network, they were proxing the attack traffic via a “private proxy network” geo-located in a few countries.
Unexpected name resolution requests
What was strange, was that while the attack was coming from Russia and Ukraine, many of these periodical DNS resolutions were instead coming from very different providers, in specific AS20473 Choopa and AS62567 Digital Ocean. So whatever that was flooding us was resolving the domain karapatan.org from inside of these providers.
By the second week of August 2021, we knew that the private proxy network inside of the Mobile Operators in Russia and Ukraine was speeding up their connections by making the name resolution of the targeted domain elsewhere.
Luminati Proxies as a DDoS botnet
A review of hundreds of servers in these DNS infrastructures revealed hundreds of proxies with the banner:
< HTTP/1.1 407 Proxy Authentication Required < X-Luminati-Error: Proxy Authentication Required < Proxy-Authenticate: Basic realm="Luminati" < Date: Sat, 21 Aug 2021 10:49:31 GMT < Connection: keep-alive < Keep-Alive: timeout=5 < Transfer-Encoding: chunked
Bright Data (formerly Luminati) with headquarters in Netanya, Israel, offers access to millions of proxies in mobile operators, data centers and residential buildings and promises to “unlock any website & collect accurate data to make data-driven business decisions”. Their business practices have long been criticized for their use of mobile VPNs and other “backdoored” Mobile Apps to gain access to residential and mobile devices.
Once we discovered how this “super proxies” infrastructures looked like, we could search for them in Censys and later on discover the locations of thousands of them by looking into their associated domains: lum-superproxy.io and l-cdn.com
We knew that the super-proxies had ports 7547, 5000-44818 open. A simple query to Censys using the 16993.https.get.headers.proxy_authenticate=Luminati or “X-Luminati-Error” in Shodan was enough to find the main locations of the super-proxies.
Luminati documentation was also enlightening as it was consistent with the DNS resolution anomaly.
Thousands of rotating IPs flooding the website
The traffic patterns we recorded were consistent with new pools of IPs rotating every hour. At the beginning of our research, we speculated that this behavior could be the result of a “pay as you go” stress testing service that allowed a maximum of one hour attack time. After several days monitoring the website we could determine that the traffic patterns were the result of Luminati automatically rotating their residential and mobile proxies in an hour basis.
During weeks, Luminati was flooding the website with no less than 100 new IPs ever hour and thousands of requests per second.
How much does the attack traffic cost?
Not surprisingly, this was the first time Qurium saw this infrastructure used for Denial of Service attacks as the Luminati traffic is far from cheap. One GB of traffic ranges between 26-35 USD for Mobile Proxies and 10-15 USD for Residential Proxies.
Only during the ten day period 10th-20th August 2021, we estimated close to 10 TB (10.000 GB) of attack traffic coming from Luminati. Using the “Plus” Package of Luminati, the attack sums up to the crazy figure of 260,000 USD for that 10-day period only.
It is difficult to believe that an attacker launching billions of requests flooding one single website has been undetected by Luminati for weeks. Only “Bright Data / Luminati Networks” will be able to bring light to this case and explain to the general public how this “business deal” was arranged.
Bright Data response to the abuse report
The 21st of August 2021, an abuse report was sent to Bright Data (Luminati Networks) about the attack. A sample of the traffic logs of the floods was shared with the company, the traffic logs included 1556 IP addresses from 68 networks of MTS and Megafon.
Some of the prefixes we shared contain more than 50 IPs engaged in the floodings.
Bright_Data_IPs Network 56 188.170.83.0/24 55 188.170.75.0/24 54 188.170.74.0/24 49 188.170.86.0/24 49 188.170.81.0/24 49 188.170.80.0/24 48 188.170.77.0/24 47 188.170.76.0/24 47 188.170.73.0/24 46 188.170.84.0/24 42 188.170.87.0/24 42 188.170.82.0/24 38 188.170.78.0/24 37 188.170.72.0/24 36 188.170.79.0/24 35 188.170.85.0/24 28 95.153.129.0/24 28 213.87.157.0/24
After some email exchanges, where Bright Data did not request more evidence, we received this fascinating explanation on August 24th.
“The IPs from the list you have attached (attaching it again) belong to Bright Data, however we did not find any of them in the requests that were sent to the reported domain. Due to the lack of findings, we keep the reported domain blocked for all of our customers, and from all of our networks, therefore we expect no requests will be sent to it through our network. Thank you for your report and hope we managed to help you sufficiently”.
As in other cases when we have traced back attack infrastructure, the email exchange finish with the common “No worries. We did not do it. It will not happen again”:
(…) we left the domain blocked so no traffic to karapatan.org will be going through our network. That way we can ensure you that no future abuse could be generated from our networks.
Original Post @ https://www.qurium.org/alerts/philippines/israeli-firm-bright-data-luminati-networks-enabled-the-attacks-against-karapatan/
About the author: Qurium Media Foundation is a Swedish non-profit digital security solutions provider, supporting independent media and human rights organizations in repressive regimes. Learn more at qurium.org or Twitter.
Follow me on Twitter: @securityaffairs and Facebook
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(SecurityAffairs – hacking, DDoS)
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