While monitoring SANS Storm Center’s honeypots today, I came across the second F5 BIGIP CVE-2020-5902 vulnerability exploitation followed by a backdoor deployment attempt. The first one was seen by Johannes yesterday .
Running the backdoor binary (ELF) on a separate system, it was possible to verify that it establishes an SSL connection to the address web[.]vpnkerio.com (52[.]32.180.34:443).
Looking for the web[.]vpnkerio.com at VirusTotal while writing this diary, I could find no AV detecting the network addresses or the binary hash as malicious.
For persistence, it writes a line on “/etc/init.d/rc.local” file on an attempt to start on system boot.
Examining the binary statically, it is possible to see the string’ python -c ‘import pty;pty.spawn(“/bin/sh”)’. It will require more analysis, but it may be used for the attacker to have an interactive terminal on the target system. A proper terminal is usually required for the attacker to run commands like ‘su’.
Exploitation attempt source
The backdoor binary
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