Threat Level: green Handler on Duty: Didier Stevens

SANS ISC: Phishing Scam Victim Response - SANS Internet Storm Center SANS ISC InfoSec Forums


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Phishing Scam Victim Response

With the start of a new school year right around the corner, there is usually an uptick in phishing scams directed toward Academia.  As has been reported many times over the past several years, the number of new faculty and students  in Higher Ed, coupled with the limited amount of access controls in place on many systems, makes this an optimal time for the scams to be directed at our campuses.

I am a huge advocate of educating these new members of our community concerning the protection of their user credentials.  For my environment, I am actively making the case that a personalized message be sent to each and every individual in our organization to educate (or at least remind) about how we conduct our business involving password changes and the use of credentials in our environment.  By in large, many of our phishing scam victims were blissfully unaware of the value to their account credentials to an attacker.  Or they just assumed an email claiming to be from the university sent to their university email account must be legit.

A number of years ago Johannes presented 6 Simple Steps to Beat Phishing [http://isc.sans.org/presentations/phishthat.pdf ].  These steps are still very valuable in the effort to limit the exposure.  Many organizations have conducted "spear phishing" attacks against their own users as a way to raise security awareness.  This type of penetration testing, or ethical hacking, likely does has some impact on the overall security posture of your users but I expect that your mileage may vary based on organizational culture.

Unfortunately, there will always be a small number of users who will fall victim to phishing scams, no matter the amount of training, education or other preventative measures you take.

So what things can you do to recover from a compromised user account.  In most of the phishing scams targeting my institution, the intruders were mostly focused on using the account to send out junk mail or other scams. 

Junk Email/Scam Attack

  • Lock out the user account or reauthorize their ability to authenticate.
  • Clean out mail queues to remove any messages which have not been delivered
  • Monitor SMTP logs to identify RBLs which may be blocking campus mail servers.
  • Reverse any changes to the compromised user account, such as Forwarding Address, Formal Name, signature, Reply-to: and similar.
  • Review logs to identify the source IP addresses of the intruders, and identify any other compromised accounts.
  • Communicate the abusive behavior to the Net Block in question, and block the IP range if appropriate.
  • Review logs to identify any tell-tale addresses which may be used by the intruders to test an account as functional.  These addresses are an excellent early warning system to identify accounts which are about to be used in an attack.
  • If available, review the content of any phishing scams directed at your organization for phrases, URLs or other details which may be included in spam filters.
  • And, obviously, communicate with the user of the account to change their account credentials to prevent unauthorized use. 



So what other things would your recommend as part of the recovery of the intrusion?  Are there are other steps that need to be followed should the intruder access other resources other than email services?


 

Scott Fendley ISC Handler

ScottF

188 Posts
ISC Handler
Depending on the phishing attempt, a full anti-virus/malware scan of the system should also be done. Many of the spear-phishing scams I've witnessed, have dropped files on the victim's PC.
Anonymous

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