SUMMARY
===
Information Security and Policy has received confirmed reports of recent
attempts to deliver the "Locky" family of Ransomware via malicious email
attachments. [1] [2]
The most recent attempts come from forged @berkeley.edu email addresses
(such as from the recipient's own email address) with Subject lines like
(note that they vary greatly):
* Document80
* Scan381
* Document5
* Doc242
* Scan0
Accompanying these emails are .ZIP file attachments (e.g. Document80.zip)
containing malicious JavaScript, Office documents with macros, or other
payloads.
The bConnected team is working closely with ProofPoint and Google to
quarantine these malicious emails before they reach campus email accounts.
However, there are many Locky variants and delivery methods used by
attackers, and sometimes these malicious emails will inevitably reach their
target.
Campus users are advised to be vigilant as Ransomware like Locky can be
extremely destructive. See the Recommendations section for guidance.
Supervisors are encouraged to circulate this Security Alert to their
departments.
IMPACT
===
Locky and other similar Ransomware will rename and scramble (encrypt) files
including videos, images, documents, and Office files rendering them
unreadable by their owner.
Only the criminal attackers that delivered the Ransomware will have the
decryption key necessary to unscramble your data, demanding payment
("ransom") in exchange for unlocking and returning your data to you.
These families of Ransomware can be particularly destructive if you do not
have secure and recent backups of your important files. Locky will also
crawl mounted network file shares and scramble any files it finds.
VULNERABLE
===
* Locky Ransomware can be delivered in a variety of different ways.
* Users that have enabled auto-execution of macros in Microsoft Office
documents are at significant risk as malicious Office documents is a
primary delivery method used by attackers dropping Locky.
* Systems that have unpatched software such as out-of-date web browsers or
Adobe Flash can also be susceptible to compromise as unpatched
vulnerabilities can be exploited to deliver the Ransomware.
RECOMMENDATIONS
===
Per the Sophos security article on Locky referenced below, here is what to
do to protect yourself against Locky and other Ransomware threats:
* Backup regularly and keep a recent backup copy encrypted on a separate
system. There are dozens of ways other than Ransomware that files can
suddenly vanish, such as fire, flood, theft, a dropped laptop or even an
accidental delete. Encrypt your backup and you won’t have to worry about
the backup device falling into the wrong hands.
* Don’t enable macros in document attachments received via email. Microsoft
deliberately turned off auto-execution of macros by default many years ago
as a security measure. A lot of malware infections rely on persuading you
to turn macros back on, so don’t do it!
* Be cautious about unsolicited attachments. The crooks are relying on the
dilemma that you shouldn’t open a document until you are sure it’s one you
want, but you can’t tell if it’s one you want until you open it. If in
doubt, leave it out.
* Don’t give yourself more login power than you need. Most importantly,
don’t stay logged in as an administrator any longer than is strictly
necessary, and avoid browsing, opening documents or other “regular work”
activities while you have administrator rights.
* Review network file share permissions. System administrators should use
this as an opportunity to review file share permissions for users and
groups, using the principle of least privilege. Damage to network file
shares (e.g. departmental share) can sometimes be limited using strict
permissions. [3]
* Consider installing the Microsoft Office viewers. These viewer
applications let you see what documents look like without opening them in
Word or Excel itself. In particular, the viewer software doesn’t support
macros at all, so you can’t enable macros by mistake!
* Patch early, patch often. Malware that doesn’t come in via document
macros often relies on security bugs in popular applications, including
Office, your browser, Adobe Flash and more. The sooner you patch, the fewer
open holes remain for the crooks to exploit.
* Learn how to spot suspicious emails by visiting our Phishing resources
page. [4]
REFERENCES
===
[1] https://en.wikipedia.org/wiki/Ransomware
[2]
https://nakedsecurity.sophos.com/2016/02/17/locky-ransomware-what-you-need-to-know/
[3] https://en.wikipedia.org/wiki/Principle_of_least_privilege
[4] https://security.berkeley.edu/resources/phishing
A web version of this Security Alert is available at:
https://security.berkeley.edu/news/locky-ransomware-delivered-email-attachments
Regards,
Josh
==
Josh Kwan <jkwan...@berkeley.edu>
Security Analyst
Information Security and Policy
University of California, Berkeley
https://security.berkeley.edu
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