Rewterz Threat Alert – New Mirai Variants could enable DDoS Attacks

Severity

Medium

Analysis Summary

Within a span of three weeks, three notable malware variants of Neko, Mirai, and Bashlite were observed. Upon analyzing Neko botnet sample, then observed another sample with additional exploits the following week. A Mirai variant that calls itself “Asher” surfaced on July 30, then a Bashlite variant called “Ayedz” the following week. These malware variants enlist infected routers to botnets that are capable of launching distributed denial of service (DDoS) attacks.

Neko

A botnet sample, x86.neko (detected by Trend Micro as Backdoor.Linux.NEKO.AB), that brute-forces weak credentials. It then issues the following commands:

The Neko botnet is capable of executing several backdoor commands: it can execute shell commands as well as launch user datagram protocol or UDP and UPD-HEX flood attacks, inundating a router’s ability to properly process and respond to information.

It is also capable of killing processes (the “killer” function is found in its body). Neko also holds within it an extensive kill list of other malware-related processes that it will terminate.

Mirai variant “Asher”

A Mirai variant (detected by Trend Micro as Backdoor.Linux.MIRAI.VWIRC). Typical of Mirai, this variant infects devices with a BusyBox, which is a software suite for devices with limited resources. It first checks for BusyBox presence by executing the “/bin/busybox {any string}” command. If the device’s system responds with “{any string} applet not found,” the bot will proceed with its operation. The malware variant’s authors used the {any string} part to “name” the malware; in this case, they used “Asher.”

Bashlite variant “Ayedz”

A Bashlite variant that seems to refer to itself as “Ayedz” (detected by Trend Micro as Backdoor.Linux.BASHLITE.SMJC, Backdoor.Linux.BASHLITE.SMJC8, and Backdoor.Linux.BASHLITE.SMJC4), based on this malware’s file name. Upon execution, Ayedz will send the following information about the infected device back to the host IP address 167[.]71[.]7[.]231 via port 46216:

Impact

• Distributed denial of service (DDoS)
• Credential theft

Indicators of Compromise

URLs

• http[:]//185[.]244[.]25[.]200/bins
• http[:]//185[.]244[.]25[.]200/bins/x86[.]neko

Malware Hash (MD5/SHA1/SH256)

• 2efae6727d3f5a4a2e7b88ef1e657f6a6e2e6e1c08af0746205dc3c7afe4094d
• 8e592655cef0dc4a1a209b6f8909a95e2bbf421ecf8312a3b4d07960fb906a5f
• 754285c82042ca8326be39988fceb39882d301fbcd3533ce31704027c445f72c
• c3626284fb68b6bf76d212441d88a5a30ae5d98b13a63b9e7358efc8c1c42215
• ebc2bb1901112c9f957855b25091c21f55a4c7d5f95b3d918f85c1924c8d31b0
• 86aa444a10c9c0c33a8f94ad71fd9d2b985e2e624872cd1c351aeaa7a4d6645f
• 416dada9ab2ae2f160363965540d5776dc2fb4e086064d97d95a11c4a90c67cd
• c81cbf35dbbe2502b32ce02cc55c307b6036d9d10f7d7a0a6da127592caeaf0a
• 5df2af777ba958b7180b71fc365595141582d8604eba7c70f635a38139503439
• abea038f41b83f00e61e829df39c4b85453335cb9a70619702a6b9834bc7d591
• b3434897b35c52551329a2f8e322d1fc1be618959794d6f4bff299c7e1ce2324
• 8cbcc1af312511ebaaba24a075333835e0ac4c4754072233bccadbb996d84048
• 329f507ceb4ed9d6a6cb5ba5e9bc6a863ef2fd12235f6ed5d46fe3ebc04cf337
• 6df1610476044ab8c3e615ddaf66e51cfe5f4a3436f37ad15fa4f6583e83fe63
• b382dce55bbc08b0f5ac7bbb231e55bb65f07e795cd6d382d9bb01b293ef2233
• 86717399a76d07b72733abb2c88cefe2d2a8c3c451d758f7c8b5249ab21b9e26
• 355df8452d6853cbf3ed44f82967d353b709b4bd04afb96de4c4a51471c0771d
• 16ebe7836ce650db686ca62d62901b771788d8ef78b7ba0a10aa73e68a710dd5
• 30d429d048a4f6ec86f48b4cd0955e0003b832213694cfa121b95e4c429d7980
• f1571b3c47ab0aeff1e8094f2e1a1da604c6867409b8509ef90333ca1e9775e1
• a2c8e598e340cc7cc27b4c045129abd9b04ddd3a592c0c41ae5c82f777b59b30
• 55355482d12b60136fde3f5d76b2686337e4bab5248e79cf3a6b2d652a290240
• 7ca9af2d71719134aa7cf8ca37d9fe35f4b20f2e5d6721e1d57f6e570e845669
• a9a5262048664843edf9e2bc405f06949cb9354ab20f5efb23dd2800c0dd4681

Remediation

• Block all threat indicators at your respective controls.
• Always be suspicious about emails sent by unknown senders.
• Never click on the link/attachments sent by unknown senders.