MikroTik RouterOS Vulnerability Allows Hackers to Perform DOS Attacks

A Serious vulnerability that discovered in MikroTik RouterOS allows attackers to perform DoS attack on the vulnerable router that causes the device to reboot.

MikroTik provides hardware and software for Internet connectivity around the world and they also created a RouterOS software.

This vulnerability allows the watchdog timer to reboots the router that causes device overloaded and eventually stop responding, the issue was addressed and fixed.

But another issue caused the memory to be filled because IPv6 route cache size could be bigger than the available RAM.

This flaw also was fixed by introducing automatic cache size calculation based on available memory, MikroTik said.

MikroTik patches flaw CVE-2018-19299, but an unpatched MikroTik router that routes the traffic via IPV6 will be affected.

It allows an attacker to take down the MikroTik router and exhausting the RAM by routes the malicious traffic via IPV6.

According to MikroTik, Both fixes are released already in RouterOS versions that were published April 2019 (all release chains: RouterOS v6.44.2, RouterOS v6.45beta23, and RouterOS v6.43.14). 

Can confirm: this also fixes CVE-2018-19299. We'll be applying this ASAP to the other half of our boxes, and urging customers running anything older that they should upgrade to 6.34.14 as a matter of urgency. https://t.co/9V0asFM22H

— Marek Isalski (@maznu) April 4, 2019

This fixes working in the following way,

• ipv6 – fixed soft lockup when forwarding IPv6 packets
• ipv6 – fixed soft lockup when processing large IPv6 Neighbor table
• ipv6 – adjust IPv6 route cache max size based on total RAM memory

it means that the current fixes possibly apply to the current version (v6.44.2) and long term (v6.43.14) release versions and this fixes only for the device that contains more than RAM 64 MB size.

UPDATE: this is *NOT* a fix on devices with 64Mb RAM (not tested on less, but suspect it is the same). https://t.co/EmNEObf8ZX

— Marek Isalski (@maznu) April 4, 2019

So if the routers with RouterOS 6.44.2 do not crash if they have enough memory.

MikroTik advised to Upgrade to any RouterOS version released after April 1st, 2019.

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