Recently, several friends of the education site and I complained, said the site does not move on the card death, live class pull to half of the students dropped all the lines, the background to see the CPU directly soared to 100% - it is clear that the CC attack through.
Education website is now simply a disaster area, the attack cost is low, but the impact is extremely bad. Think about it, you are on a live class with a famous teacher, suddenly the screen is stuck as a PPT, students and parents complained that the phone can blow your landline. More disgusting is that many attacks are also disguised as normal traffic, traditional firewalls can not stop.
Last year, I helped an online education platform to do emergency response, they used a well-known cloud vendor's basic protection, the results encountered HTTP slow attack, a few bytes of packets per second, the connection pool was instantly occupied, normal users can not connect. The technical team realized that the default CC rules hadn't taken effect at all.
Why are educational websites particularly vulnerable? First of all, the domain name exposure is high, course links are forwarded everywhere; secondly, the live business must be open ports, the attacker can find a random interface to send crazy packets. Not to mention that some teaching platforms still use the old ThinkPHP, any historical vulnerability can be penetrated.
Simply adding bandwidth is a bottomless pit. I have tested, 100G of DDoS traffic can make the monthly salary of 30,000 operation and maintenance overnight reboot servers, and CC attacks do not even need too much traffic, a few botnets take turns requesting the login page, the database can collapse to you.
High defense CDN is the king. However, many people think that they can just buy a CDN with protection and everything will be fine, and the result is that the first hit will be worn. The key lies in the configuration - many vendors only open the basic protection by default, and the refined rules have to be matched by themselves.
First, let's talk about selection. Don't be superstitious about the international manufacturers, the domestic scene must also look at the local service providers. Like CDN5's anti-CC algorithm is really powerful, through the JS challenge + behavioral analysis, can identify 99% simulation request; CDN07's live acceleration line is really stable, the evening peak can ensure that <100ms delay; if the budget is limited, 08Host cost-effective program is worth a look, although the console is ugly, but the bottom is also used in self-developed cleaning algorithms.
Here comes the point: configure high defense CDN is never a simple change of CNAME on the line. You have to do strategy tuning according to the business characteristics of the educational station. I generally divided into four steps: business image → rules nesting → stress test → dynamic adjustment.
Let's start with the business portrait. Divide the website interface into three categories: static resources (images/CSS), dynamic interface (login/comments), and core business (live push streaming/paid interface). Static resources are directly cached to the edge node, dynamic interfaces must go through the cleaning rules, and core business should be set up separately with whitelisting + rate limiting.
Live stream protection is the most troublesome. Attackers now specialize in hitting the push stream forensic interface, a hit. My suggestion is to parse the name of the push stream separately to the high defense line, and configure a strict frequency control policy in the CDN background:
Don't believe the propaganda of "one-click to turn on full protection". Last year, an educational platform opened a vendor's strict mode, and as a result, all students in Xinjiang and Tibet were blocked - because the vendor's IP database had not been updated, and the base station IPs in those areas were misjudged as proxy IPs.
Behavioral validation strategy should be gradient. For the login interface, the first 3 failures are verified with a slider, and more than 5 failures directly trigger a JS challenge + client fingerprint record. Validation algorithms like CDN5 can distinguish between real browsers and Python scripts, I've tested simulating clicks with Selenium, and I can pass at most two out of ten times.
The caching strategy has to be optimized as well. Static course videos should definitely be cached, but dynamic data has to be careful. There's a pitfall: many platforms cache the student answer record interface as well, resulting in seeing all the wrong data. Remember to use Cookie or Header variables to make differentiated cache keys:
The key to the smoothness of the live broadcast is in the link optimization. Education station users are widely distributed, telecommunications, Unicom, mobile and even education network should be taken into account. CDN07's three major carriers dedicated line is the most stable I've ever used, support for BGP intelligent routing, Harbin students and teachers in Hainan together with a live room, the latency can be controlled within 80ms.
Here's another tip: Use RTMPS on the push side and HLS+low latency mode on the pull side. In this way, even if you encounter unexpected traffic, CDN can reduce the bit rate to ensure smoothness, and the student side will at most have a muddy picture, but not to the point of card breaks.
Don't forget to monitor alerts: CPU utilization, QPS, 4xx/5xx error codes should all be thresholded. Multi-dimensional statistics are recommended: for example, "Guangdong Telecom users accessing the live interface with 5xx anomalies > 10%" will be alerted immediately, which is probably the beginning of a regional attack.
Finally remind a hidden cost: bandwidth billing method. 08Host 95 peak billing can save 30% cost, but the sudden flow of large stations best selection of fixed bandwidth per month. Once an education platform to do free open class, traffic surge bill directly after the 5 times, the financial almost to the operation and maintenance of the sacrifice.
In the actual battle encountered the most tricky attack: the attacker used 2000 cloud function nodes, each node every 5 minutes to request an enrollment interface, directly bypassing the frequency control rules. In the end, it was the client fingerprint library of CDN5 + threat intelligence linkage that stopped it - so the CDN must look at the frequency of threat intelligence updates, and it is best to synchronize the latest malicious IP library every day.
Nowadays, educational attacks are becoming more and more accurate, and even attackers will listen to a normal class for half an hour before suddenly attacking. High-defense CDN must be equipped with WAF+behavioral analysis in order to prevent this kind of "slow attack", and the money cannot be saved on security.
In short, there is no silver bullet for education station protection, and the core is "business understanding + deep configuration". Good CDN vendors can provide you with customized strategies, such as for the early morning peak period to reduce the level of protection to save money, the examination period to fully open the strict mode. Don't forget to do a monthly attack and defense drill, script kiddies can have more tricks than you think.
