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PT0-001 · Question #170

A penetration tester executed a vulnerability scan against a publicly accessible host and found a web server that is vulnerable to the DROWN attack. Assuming this web server is using the IP address…

The correct answer is A. Openssl s_client -tls1_2 -connect 127.212.31.17:443. The DROWN attack exploits SSLv2 weaknesses; to verify a false positive, the tester must use openssl in client mode with a valid modern protocol flag to confirm the server's actual TLS negotiation behavior.

Vulnerability discovery and analysis

Question

A penetration tester executed a vulnerability scan against a publicly accessible host and found a web server that is vulnerable to the DROWN attack. Assuming this web server is using the IP address 127.212.31.17, which of the following should the tester use to verify a false positive?

Options

  • AOpenssl s_client -tls1_2 -connect 127.212.31.17:443
  • BOpenssl s_client -ss12 -connect 127.212.31.17:443
  • COpenssl s_client -ss13 -connect 127.212.31.17:443
  • DOpenssl s_server -tls1_2 -connect 127.212.31.17:443

How the community answered

(35 responses)
  • A
    54% (19)
  • B
    6% (2)
  • C
    29% (10)
  • D
    11% (4)

Why each option

The DROWN attack exploits SSLv2 weaknesses; to verify a false positive, the tester must use openssl in client mode with a valid modern protocol flag to confirm the server's actual TLS negotiation behavior.

AOpenssl s_client -tls1_2 -connect 127.212.31.17:443Correct

The command `openssl s_client -tls1_2 -connect 127.212.31.17:443` uses the correct client-side subcommand (`s_client`) to initiate a handshake with the target server, forcing TLS 1.2 negotiation to confirm the server's protocol support baseline. If the server only supports TLS 1.2 and SSLv2 is not actually enabled, the DROWN finding would be confirmed as a false positive. This syntax is the standard method for manually verifying a server's SSL/TLS configuration against a scanner result.

BOpenssl s_client -ss12 -connect 127.212.31.17:443

The `-ssl2` flag attempts to connect using the deprecated SSLv2 protocol, which would confirm the vulnerability rather than rule it out as a false positive, and `ss12` is not a valid OpenSSL flag.

COpenssl s_client -ss13 -connect 127.212.31.17:443

The `-ssl3` flag tests SSLv3 connectivity rather than SSLv2, so it does not directly address the DROWN vulnerability and cannot be used to verify whether that specific scanner finding is a false positive.

DOpenssl s_server -tls1_2 -connect 127.212.31.17:443

The `s_server` subcommand puts OpenSSL into server mode to accept incoming connections, not client mode, so it cannot be used to connect to and test an external target host.

Concept tested: DROWN vulnerability verification using OpenSSL client

Source: https://www.openssl.org/docs/man1.1.1/man1/openssl-s_client.html

Topics

#DROWN attack#SSLv2#OpenSSL#vulnerability verification

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