Threat Advisories and Attack Reports

BrickerBot PDoS Attack: Back With A Vengeance

BrickerBot PDoS Attack: Back With A Vengeance

A new version of the BrickerBot PDoS attack has been discovered and researched by Radware’s Emergency Response Team. Download a Copy Now

Abstract

Imagine a fast moving bot attack designed to render the victim’s hardware from functioning. Called Permanent Denial-of-Service Attack (PDoS Attack), this form of cyber-attack is becoming increasingly popular in 2017 as more incidents involving this hardware-damaging assault occur.

In early April, Radware’s Emergency Response Team identified a new botnet designed to comprise IoT devices and corrupt their storage. Over a four-day period, Radware’s honeypot recorded 1,895 PDoS attack attempts performed from several locations around the world. Its sole purpose was to compromise IoT devices and corrupt their storage.

Besides this intense, short-lived bot (BrickerBot.1), Radware’s honeypot recorded attempts from a second, very similar bot (BrickerBot.2) which started PDoS attack attempts on the same date – both bots were discovered less than one hour apart –with lower intensity but more thorough and its location(s) concealed by TOR egress nodes.

BrickerBot.3 – Back With A Vengeance

Radware’s Emergency Response Team has now discovered a new version of the BrickerBot PDoS attack (BrickerBot.3) with a new command sequence:

Figure 1: The command sequence for BrickerBot.3

Compared with the original BrickerBot.1, the sequence of commands is very similar. It does not start with fdisk – but goes straight to business. The first 6 block devices it tries to corrupt (up to and including /dev/ram0) correspond with the BrickerBot.1 PDoS attack.

Figure 2: For reference, the BrickerBot.1 command sequence

The devices mtd0,1 and mtdblock1,2,3 are new for the busybox version of BrickerBot. The fdisk commands that try to change the geometry of the block devices are identical to what BrickerBot.1 attempted. The end sequence again tries to disrupt connectivity by removing the default route and disabling TCP timestamps, wipe the root and limit the number of kernel threats to 1. The fork bomb ( https://en.wikipedia.org/wiki/Fork_bomb) which was a signature feature for BrickerBot.2 is not present.

The First 12 Hours

During the first 12 hours of the attack, a total of 1118 PDoS attack attempts were recorded. The attacks all originated from a limited number of clear net IP addresses. ZoomEye (https://www.zoomeye.org/) and Shodan (https://www.shodan.io/) searches based on the source IPs of the attacks revealed all of them running an outdated version of the Dropbear SSH server (SSH-2.0-dropbear_0.51, SSH-2.0-dropbear_2013.58, and SSH-2.0-dropbear_2014.63).

The PDoS attacks started at 12:00 GMT on April 21st and in its first 12 hours the number of bots performing the attacks grew up to 15 bots.

Figure 3: Bot growth timeline over a 12 hour period

The devices used to perform the PDoS attacks on Radware’s honeypot do not correspond to the devices from BrickerBot.1. Although BrickerBot.1 was also abusing a limited number of clearnet connected devices to perform its attack, there is no immediate correlation between both. For complete disclosure and transparency, the attacks were detected by a different honeypot than the one that detected the BrickerBot.1 and BrickerBot.2 attacks.

The devices that perform the PDoS attack are spread around the globe and do not concentrate in a specific region and do not correlate to the locations of the BrickerBot.1 sources.

Figure 4: Geographic distribution of devices used by BrickerBot.2 to perform attacks

An Exploit Vector Like Mirai

In line with BrickerBot.1 and BrickerBot.2, this bot is also using the Mirai exploit vector to compromise the target. Any ‘busybox’ based Linux device that has Telnet exposed publically and has factory default credentials unchanged are a potential victim.

BrickerBot.4

Between 5:22pm and 8:44pm GMT the same honeypot also detected yet another, very similar sequence of commands. The PDoS attack was only attempted from a single device which was located on the Clearnet and upon investigation also had an outdated version of the Dropbear SSH server (SSH-2.0-dropbear_2014.63). This isolated bot performed 90 attacks and was not seen again between 8:44pm and midnight.

Figure 5: The BrickerBot.4 command sequence has a few less block devices it attempts to corrupt compared to BrickerBot.3

The Author: Rob the Janit0r

A few hours after finalizing this report, Catalin Cimpanu published his article on the author of BrickerBot ( https://www.bleepingcomputer.com/news/security/brickerbot-author-claims-he-bricked-two-million-devices/). A person who went by the name of Janit0r on Hackerforums alluded to be the author of BrickerBot on April 14th.

Figure 6: Excerpt of a conversation that includes JanitOr

The Janit0r reached out to Victor Gevers ( https://twitter.com/0xDUDE) based on a comment Victor made in one of the first articles on BrickerBot.1 and .2. The person confirmed he is the Janit0r on Hackforums and he is the author of BrickerBot.

Like so many others I was dismayed by the indiscriminate DDoS attacks by IoT botnets in 2016. I thought for sure that the large attacks would force the industry to finally get its act together, but after a few months of record-breaking attacks it became obvious that in spite of all the sincere efforts the problem couldn't be solved quickly enough by conventional means.” The Janit0r

Based on the Janit0r’s discussion, BrickerBot is more complex and probably much larger than Radware initially believed.

I consider my project a form of "Internet Chemotherapy" I sometimes jokingly think of myself as The Doctor. Chemotherapy is a harsh treatment that nobody in their right mind would administer to a healthy patient, but the Internet was becoming seriously ill in Q3 and Q4/2016 and the moderate remedies were ineffective.” The Janit0r

For the time being, it does not seem like the Janit0r will stop BrickerBot attacks, or at least not until officials and hardware vendors take definitive action to improve the state of IoT security.

The Potential Damage

BrickerBot.3 and BrickerBot.4, like BrickerBot.1, are targeting ‘busybox’-based Linux devices, typically IoT devices such as IP camera’s and DVRs. As mentioned in Radware’s BrickerBot blog from April 13th ( https://blog.radware.com/security/2017/04/brickerbot-dark-knight-iot/), Radware tested the BrickerBot.1 PDoS attack command sequence and accessed its impact on a real life device. The device in question was a Sricam AP003 Metal Gun Type Waterproof Outdoor Bullet ( https://www.amazon.com/Sricam-AP003-Waterproof-Wireless-Security/dp/B00MCKG1FY) IP camera which is known to be ‘supported’ by Mirai.

Although this suggests thoughts of robustness, upon running the sequence of commands from BrickerBot.1, the camera got disconnected from the network and upon reboot was not responding anymore. Factory provided via button on the camera did not recover the IoT device. It was effectively bricked.

Protecting Your IoT Devices

It is not possible to assess how widely spread the attacks are, but the potential damage BrickerBot.3 poses a clear and present danger for any IoT device with factory default credentials. As the PDoS attacks are still ongoing, Radware advises the following:

Change the device’s factory default credentials.

Disable Telnet access to the device.

Use Network Behavioral Analysis to detect anomalies in traffic and combine this with automatic signature generation for fast and effective mitigation.

Use User/Entity behavioral analysis (UEBA) to spot granular anomalies in traffic early.

Gateway devices allow blocking Telnet default credentials. Use a DPI signature to detect default credentials and/or provided command sequences.

The commands used in these PDoS attack attempts are more thorough than the previously described ones. The targeted storage devices are much broader and there is no use of 'busybox' while attempting both 'dd' and 'cat,’ whichever is available on the breached device.

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