Threat Management

South Korea no 1 origin point for DDoS attacks

South Korea has taken the top spot as the largest origin point for DDoS attacks in 2016. 

Imperva documented DDoS attacks coming out of South Korea at a rate nearly triple that of Russia, which came in second. In fact, South Korea attained a proportion of global DDoS responsibility greater than the next three countries combined.

DDoS attacks are one of the more popular tools in the hacker's toolkit. DDoS, or distributed denial of service attacks, work by essentially flooding the target with traffic. Attackers will normally employ botnets to do this, making it seem as though millions of people are all visiting the same site at the exact same second.

Though a favourite of hacktivists, the attack is also employed by cyber-criminals, often using it as a smokescreen to distract defenders while stealing information from the parts of networks that are left undefended. The blackmail group DD4BC, for example, would relentlessly DDoS websites until the unfortunate victims coughed up a couple of bitcoins.

Ewan Lawson, a Royal United Services Institute fellow and expert in cyber-security, offered insight as to why South Korea might have reached this zenith. Lawson told, “It feels like it is in part a reflection of the networked nature of [South Korea] but there are other countries with similar degrees of penetration or greater.”

South Korea has one of the highest internet penetration rates in the world and also enjoys one of the faster internet speeds, last year rated at an average of 23.6 Mbps. “It would therefore suggest”, said Lawson, “that there is some vulnerability in the gateways and/or servers that are being exploited by the DDoS enabling malware.”

Igal Zeifman, senior manager at Imperva, told SC, “As a rule, botnets thrive either in regions with high Internet connectivity or in emerging Internet markets with a high prevalence of unsecured connected devices.”

Zeifman added, “South Korea certainly fits the former scenario, with botnet shepherds benefiting from the organic evolution in connection speeds—something that also improves the attacking (upload) capabilities of compromised devices.”

Botnets have been growing rapidly in South Korea over the past year. The South Korean DDoS activity primarily comes from two botnets - Nitol and PCRat - both of which offer remote control over the infected devices. 

Where they differ is their attack traffic signatures, Zeifman told SC. Nitol, for example, is a Chinese botnet and will probably send out attack disguised as search engine crawlers from Baidu, an immensely popular Chinese website.

Jarno Limnell, professor of cyber-security at Aalto university in Finland, explained to SC that both of these botnets are Windows based: “A typical 'member' of a botnet is, therefore, a Windows PC. The easiest way to do it - non-updated (and possibly illegal) Windows with the appropriate vulnerability. I guess that in South Korea there a lot of these kind of PCs available to build botnets.”

Russia and Ukraine came second and third respectively. Though beaten by South Korea, Zeifman told SC that the two countries owe much of their increased activity to “the emergence of new botnets built out of Windows OS devices compromised with the Generic!BT malware”.

Zeifman added this may be indicative of poor security in those countries: “The fact that a known, and pretty outdated, type of malware is successfully being used points to inefficient security measures on the part of device owners.”

Meanwhile, and perhaps unsurprisingly, the United States was the most DDoSed country in the world over the last quarter, far outpacing the combined total of the other nine most DDoSed countries.

Some of the report's other findings included the fact that DDoS attacks, are “upping their game” when it comes to botnets. Imperva's report says this, “this was best exemplified by an increase in the number of DDoS bots with an ability to slip through standard security challenges, commonly used to filter out attack traffic.”

Over the first quarter of this year, the number of these kinds of bots “mushroomed” from 6.1 percent to 36.6 percent, as a proportion of total bots.

What makes them different is that some of these bots can hold cookies while others can spot javascript, making for a deadly combination.

DDoS attackers are also narrowing their gazes. Imperva notes that while DDoS attacks may have once been brutish and crude, the company is seeing far more finesse in the deployment. Attackers have been experimenting with new methods and vectors, which the reports says suggests “that more perpetrators are now re-prioritising and crafting attacks to take down DDoS mitigation solutions, rather than just the target.” 

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