Best Tool Against Hacker Attacks a Smart Network Administrator

The   best   tool   against   hacker attacks   is   a   smart   network administrator.

This article will show how to use Hydra to check for weak passwords. Hydra tries all possible password combination against a server on the Internet until one valid one is found to log in to the server. It is a powerful tool for hackers and network administrators alike.

Please notice that no blog entry is published in order to cause any damage or to motivate people harming something/someone. I believe in the fact that information should be free and shared among each other. It is not my responsibility if someone abuses the knowledge which can be found here. Please always respect and know your local laws.

Yeah, again an article on how to choose secure passwords   Unbreakable, long and complicated so they are impossible to remember… Not really! This article is different! In this article I will talk from the attacker  point of view. Why  it is not   trivial   to   brute   force   a password.   I   will   explain   how Hydra can help to test for  weak passwords.   Hydra   is   available from­ hydra/.

It is supposedly the best network   login   cracking   tool available today. This  article  will  only  give  you  a broad overview of the potential of Hydra. You will figure out the rest by yourself.

First   make   your   network   as secure   as   you   can.   Make   no mistakes: One  small  mistake  by you,   one   giant   leap   for   the attacker.

  • • Set up a test network
  • • Set up a test server
  • • Configuring services
  • • Configure ACL
  • • Choosing good passwords
  • • Use SSL
  • • Use cryptography
  • • Use an IDS.

…then let Hydra try to break into your own server!

Setting up networks The Internet is standardized. It will either be IPv4 or IPv6. Hydra can attack IPv4 and IPv6 networks alike. Use the ­6 option to switch to IPv6.

Configuring services and access controls Common protocols for mail are SMTP, POP3 and IMAP4. They are used by small and large businesses alike, heck they are even used by gmail, hotmail and other big players: Most of those biggies support one of those protocols beside the web based login known to most of you. Your password is at risk even if you never ever used SMTP, POP3 or IMAP. Use the ­h option in Hydra to get a full list of supported protocols.

A common mistake of many new server   installations   is   that   they come   with   services   like   POP3, IMAP or SSH enabled by default. Access   control   and   firewall   are disabled by default. New default servers   are   an   easy   target   for Hydra

Shell 1. Choosing IP version from command line

#./hydra ­l john ­p doe imap://

#./hydra ­l john ­p doe imap://[::FFFF:]:143 ­

Shell 2. Bruteforce password generator option

#./hydra ­l john ­x 5:8:A1 imap://

Shell 3. Set SASL method on command line

#./hydra ­l john ­p doe imap://­MD

Choosing good passwords

Passwords   are   often   chosen carelessly. 90% of all users pick one   of   the   10   most   common passwords   at   some   point   on some system.

123456,   password,   secret,   … look familiar?

Might as well not use a password at all then! Hydra   also   has   a   special command line option: Use “­e ns” to   check   for   empty   passwords and   where  the  password   is   the username! Hydra   can   work   through   list   of common   passwords   or   can mutate the passwords randomly. Use the ­x option for mutating the password. For  example use “­x 5:8:A1 “  to try all password of length 5 to 8 by   using   all   possible combinations   of   all   upper   case characters and all numbers.

Using SSL and cryptographic methods Using   encryption   like   SSL   does not help. SSL is primarily used to encrypted  the  sessions  between attacker   and   server.   This   is   an advantage for the attacker as the attack   is   not   picked   up   by   a network   Intrusion   Detection System (IDS).

SSL   is   almost   never   used   to authenticate a client. Client side authentication   is   done   by traditional   password authentication   in   almost   all servers.

Research  has  shown  that users using   SSL   chose   weaker password for the SSL connection than   for   connections   not   using SSL.   It   appears   there   is   some false  sense  of security  lingering among all the good, bad and ugly things with SSL. This is where Hydra attacks. In   cryptography   if   you   do   not understand it do not use it! Beside   SSL   does   Hydra   also support   SASL   (CRAM­MD5, DIGEST­MD5   and   SCRAM­ SHA1).

The   “Simple   Authentication   and Security   Layer”   (SASL)   is   a framework for  authentication and data security in Internet protocols. It   decouples   authentication mechanisms   from   application protocols.

GNU project has  implemented it through   the   GNU   SASL   Library called   GSASL   (see

When   the   server   is   negotiating secure  channel, secure  method, Hydra just respond “ok let’s do it”, and   generates   valid   credential based on the challenge sent. The  SASL  method  can  be  used as   shown   above.   Use   the   ­U option   to   get   a   full   list   of supported SASL options.

Monitoring   access and resources

More   and   more   companies   are buying   SIEM   (Security Information   and   Event Management)   to   centralized   the event access logs. This could be useful  to  track  abnormal  events on the network, like for  example many authentication failures on a given service. This kind of tool, is used to save your  time, it could also  automatically  alerts   you  by using   some   correlated   rules   to detect malicious events. No   SIEM   prevents   the   attack. They merely inform you after the event.   After   Hydra   got   in.   After your data got stolen.

Sometimes the SIEM or the IAM (Identity   and   Access Management)   can   become   the way   of   entry   as   well!   These services   are   using   LDAP.   And guess what, Hydra also supports LDAP. IPS   (Intrusion   Prevention System)   is   a   must   have   in   a corporate   network,   nowadays such kind of device always come

with   predefined   signatures   to detect password cracking attacks. However, they have a weak point, they are based on a defined rate.

For   example   if   there   are   10 authentication failed in 5 seconds from   the   same   source   IP   just block  or  quarantine  the  attacker for x seconds. For   this   purpose   Hydra   comes with  some  features  to  plan  how the   attack   is   conducted.   The   ­t option   can   be   used   to   set   the number   of   concurrent   tasks (default is 16). Setting it to 1 and you  will  stay  under  the  radar  of any IDS.


Chose your password wisely. Do not let  IDS,  IPS, SIEM, IAM  or SSL lure you into a false sense ofsecurity.

Try   Hydra.   Make   sure   you   are safe and secure.

The   best   tool   against   hacker attacks   is   a   smart   network administrator.


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  1. Pingback: cyber crimes -Who Done It? | US Cyber Labs - Blog

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