Posts Tagged: imperva

Mar 18

Powerful New DDoS Method Adds Extortion

Attackers have seized on a relatively new method for executing distributed denial-of-service (DDoS) attacks of unprecedented disruptive power, using it to launch record-breaking DDoS assaults over the past week. Now evidence suggests this novel attack method is fueling digital shakedowns in which victims are asked to pay a ransom to call off crippling cyberattacks.

On March 1, DDoS mitigation firm Akamai revealed that one of its clients was hit with a DDoS attack that clocked in at 1.3 Tbps, which would make it the largest publicly recorded DDoS attack ever.

The type of DDoS method used in this record-breaking attack abuses a legitimate and relatively common service called “memcached” (pronounced “mem-cash-dee”) to massively amp up the power of their DDoS attacks.

Installed by default on many Linux operating system versions, memcached is designed to cache data and ease the strain on heavier data stores, like disk or databases. It is typically found in cloud server environments and it is meant to be used on systems that are not directly exposed to the Internet.

Memcached communicates using the User Datagram Protocol or UDP, which allows communications without any authentication — pretty much anyone or anything can talk to it and request data from it.

Because memcached doesn’t support authentication, an attacker can “spoof” or fake the Internet address of the machine making that request so that the memcached servers responding to the request all respond to the spoofed address — the intended target of the DDoS attack.

Worse yet, memcached has a unique ability to take a small amount of attack traffic and amplify it into a much bigger threat. Most popular DDoS tactics that abuse UDP connections can amplify the attack traffic 10 or 20 times — allowing, for example a 1 mb file request to generate a response that includes between 10mb and 20mb of traffic.

But with memcached, an attacker can force the response to be thousands of times the size of the request. All of the responses get sent to the target specified in the spoofed request, and it requires only a small number of open memcached servers to create huge attacks using very few resources.

Akamai believes there are currently more than 50,000 known memcached systems exposed to the Internet that can be leveraged at a moment’s notice to aid in massive DDoS attacks.

Both Akamai and Qrator — a Russian DDoS mitigation company — published blog posts on Feb. 28 warning of the increased threat from memcached attacks.

“This attack was the largest attack seen to date by Akamai, more than twice the size of the September, 2016 attacks that announced the Mirai botnet and possibly the largest DDoS attack publicly disclosed,” Akamai said [link added]. “Because of memcached reflection capabilities, it is highly likely that this record attack will not be the biggest for long.”

According to Qrator, this specific possibility of enabling high-value DDoS attacks was disclosed in 2017 by a Chinese group of researchers from the cybersecurity 0Kee Team. The larger concept was first introduced in a 2014 Black Hat U.S. security conference talk titled “Memcached injections.”


On Thursday, KrebsOnSecurity heard from several experts from Cybereason, a Boston-based security company that’s been closely tracking these memcached attacks. Cybereason said its analysis reveals the attackers are embedding a short ransom note and payment address into the junk traffic they’re sending to memcached services.

Cybereason said it has seen memcached attack payloads that consist of little more than a simple ransom note requesting payment of 50 XMR (Monero virtual currency) to be sent to a specific Monero account. In these attacks, Cybereason found, the payment request gets repeated until the file reaches approximately one megabyte in size.

The ransom demand (50 Monero) found in the memcached attacks by Cybereason on Thursday.

Memcached can accept files and host files in temporary memory for download by others. So the attackers will place the 1 mb file full of ransom requests onto a server with memcached, and request that file thousands of times — all the while telling the service that the replies should all go to the same Internet address — the address of the attack’s target.

“The payload is the ransom demand itself, over and over again for about a megabyte of data,” said Matt Ploessel, principal security intelligence researcher at Cybereason. “We then request the memcached ransom payload over and over, and from multiple memcached servers to produce an extremely high volume DDoS with a simple script and any normal home office Internet connection. We’re observing people putting up those ransom payloads and DDoSsing people with them.” Continue reading →

Nov 15

The Lingering Mess from Default Insecurity

The Internet of Things is fast turning into the Internet-of-Things-We-Can’t-Afford. Almost daily now we are hearing about virtual shakedowns wherein attackers demand payment in Bitcoin virtual currency from a bank, e-retailer or online service. Those who don’t pay the ransom see their sites knocked offline in coordinated cyberattacks.  This story examines one contributor to the problem, and asks whether we should demand better security from ISPs, software and hardware makers.

armyThese attacks are fueled in part by an explosion in the number of Internet-connected things that are either misconfigured or shipped in a default insecure state. In June I wrote about robot networks or “botnets” of hacked Internet routers that were all made and shipped by networking firm Ubiquiti. Attackers were able to compromise the routers because Ubiquiti shipped them with remote administration switched on by default and protected by a factory default password pair (ubnt/ubnt or no password at all).

That story followed on reports from security firm Imperva (see Lax Security Opens the Door for Mass-Scale Hijacking of SOHO Routers) which found a botnet of tens of thousands of hijacked Ubiquiti routers being used to launch massive ransom-based denial-of-service attacks. Imperva discovered that those tens of thousands of hacked devices were so easy to remotely control that each router was being exploited by several different extortion groups or individual criminal actors. The company also found those actors used the hacked routers to continuously scan the Internet for more vulnerable routers.

Last week, researchers in Vienna, Austria-based security firm SEC Consult released data suggesting that there are more than 600,000 vulnerable Ubiquiti routers in use by Internet service providers (ISPs) and their customers. All are sitting on the Internet wide open and permitting anyone to abuse them for these digital shakedowns.

These vulnerable devices tend to coalesce in distinct geographical pools with deeper pools in countries with more ISPs that shipped them direct to customers without modification. SEC Consult said it found heavy concentrations of the exposed Ubiquiti devices in Brazil (480,000), Thailand (170,000) and the United States (77,000).

SEC Consult cautions that the actual number of vulnerable Ubiquiti systems may be closer to 1.1 million. Turns out, the devices ship with a cryptographic certificate embedded in the router’s built-in software (or “firmware”) that further weakens security on the devices and makes them trivial to discover on the open Internet. Indeed, the Censys Project, a scan-driven Internet search engine that allows anyone to quickly find hosts that use that certificate, shows exactly where each exposed router resides online.

The Imperva research from May 2015 touched a nerve among some Ubiquiti customers who thought the company should be doing more to help customers secure these routers. In a May 2015 discussion thread on the company’s support site, Ubiquiti’s vice president of technology applications Matt Harding said the router maker briefly disabled remote access on new devices, only to reverse that move after pushback from ISPs and other customers who wanted the feature turned back on.

In a statement sent to KrebsOnSecurity via email, Harding said the company doesn’t market its products to home users, and that it sells its products to industry professionals and ISPs.

“Because of this we originally shipped with the products’ configurations as flexible as possible and relied on the ISPs to secure their equipment appropriately,” he said. “Some ISPs use self-built provisioning scripts and intentionally locking down devices out of the box would interfere with the provisioning workflows of many customers.”

Harding said it’s common in the networking equipment industry to ship with a default password for initial use. While this may be true, it seems far less common that networking companies ship hardware that allows remote administration over the Internet by default. He added that beginning with firmware version 5.5.2 — originally released in August 2012 — Ubiquiti devices have included very persistent messaging in the user interface to remind customers to follow best practices and change their passwords.

“Any devices shipping since then would have this reminder and users would have to intentionally ignore it to install equipment with default credentials,” he wrote.  Harding noted that the company also provides a management platform that ISPs can use to change all default device passwords in bulk.

Ubiquiti's nag screen asking users to change the default credentials. The company's devices still ship with remote administration turned on.

Ubiquiti’s nag screen asking users to change the default credentials. The company’s devices still ship with remote administration turned on.

Continue reading →

Oct 13

Thousands of Sites Hacked Via vBulletin Hole

Attackers appear to have compromised tens of thousands of Web sites using a security weakness in sites powered by the forum software vBulletin, security experts warn.

Attack tool for exploiting vulnerable vBulletin forums.

Attack tool for exploiting vulnerable vBulletin forums.

In a blog post in late August, vBulletin maker Jelsoft Internet Brands Inc. warned users that failing to remove the “/install” and “/core/install” directories on sites running 4.x and 5.x versions of the forum software could render them easily hackable. But apparently many vBulletin-based sites didn’t get that memo: According to Web site security firm Imperva, more than 35,000 sites were recently hacked via this vulnerability.

The security weakness lets attackers quickly discover which forums are vulnerable, and then use automated, open-source exploit tools to add administrator accounts to vulnerable sites.

Imperva said the compromised sites appear to have been hacked by one of two sets of exploit tools that have been released publicly online. The first was apparently used in a mass Website defacement campaign. A Google search for forums with the the rather conspicuously-named administrator account added in that attack (“Th3H4ck”) shows that many of the hack sites also are hosting malware. Among the sites apparently compromised is a support forum for the National Runaway Safeline and a site selling vBulletin add-ons.

The second tool does effectively the same thing, except with a bit more stealth: The administrator account that gets added to hacked forums is more innocuously named “supportvb”. Here’s a Google search that offers a rough idea of the forums compromised with this exploit, which was apparently authored or at least publicly released by this guy.

Continue reading →

Jan 11

Ready for Cyberwar?

Amid all of the media and public fascination with threats like Stuxnet and weighty terms such as “cyberwar,” it’s easy to overlook the more humdrum and persistent security threats, such as Web site vulnerabilities. But none of these distractions should excuse U.S. military leaders from making sure their Web sites aren’t trivially hackable by script kiddies.

Security vendor Imperva today blogged about a hacker who claims to have access to and control over several top dot-gov, dot-mil and dot-edu Web sites. I’ve seen some of the back-end evidence of his hacks, so it doesn’t seem like he’s making this up. Perhaps out of deference to the federal government, the Imperva folks blocked out the best part of that screen shot — the actual names of the Web site domains that this hacker is selling. For example, the hacker is advertising full control and root access to, a site whose stated purpose is “to develop, acquire, provide and sustain world-class…systems and Battle Command capabilities for the joint warfighter.” It can be yours, for just $499 (sorry, no credit cards accepted; only the virtual currency Liberty Reserve).

Here is an unredacted (well, mostly) shot of that site:

Continue reading →