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`Exhibit 17
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`Case 3:17-cv-05659-WHA Document 369-18 Filed 02/14/19 Page 2 of 3
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`3. The ransomware enumerates all the fi les it needs to encrypt using a hard coded list of data
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`file extensions.
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`4.
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`It then generates loca lly a set of private symmetric keys to be used for encrypting the fi les.
`Symmetric keys are used for both encryption and decryption. In some cases one key per
`file is generated, in other cases it could be one key per file extension or just one key for the
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`entire set. It all depends on how paranoid the malware author is.
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`5. The ransomware uses the private key algorithm and the symmetric private keys generated
`in the previous step to encrypt the files.
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`6. Then the private encryption keys themselves are encrypted using the public key from step
`two. The result is sto red in the victim's computer's key store.
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`7. The ransom note is displayed, sometimes with an incentive to pay quickly.
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`Decryption
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`1. Once the malware operator receives payment, the private key from the C&C server is sent
`to the ransomwa re decryptor code.
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`2. This private key is then used to decrypt the symmetric private keys used earlier to encrypt
`the fi les and which were stored in the local key store.
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`3. The symmetric private keys obtained are used to decrypt and recover the origina l data files.
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`Earlier versions of ransomware like CryptoWal l 2.0 were not as sophisticated and used the
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`public key directly to encrypt data fi les. Cryptowall 3.0 evolved to the process above comb ining
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`public/private keys and symmetric keys. Cerber uses a comb ination of RSA public/private keys
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`and RC4 keys. Typically, a co mbination of AES and RC4 encryption algorithms are used with
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`varying ciphers.
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`Cyphort's Ability to Detect Ransomware
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`Detecting ransomware can be doe using network-based detection or endpoint-based detection.
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`We wil l focus on network-based detection and more specifical ly how Cyphort detects these
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`advanced threats.
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`Cyphort's advanced detection fabric includes multiple detection and analytics capabilities, which
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`work together to quickly identify advanced targeted attacks like ransomware. These capabilities
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`are summa rized below.
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`Object Analys is Pipeline
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`All files analyzed by Cyphort go through a mu lti-stage detection pipeline with in the SmartCore
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`analytics angine, which is comprised of the fol lowing components:
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`• Static AV Engine - leverages top-tier Anti-Virus technology w ith very frequent signature
`updates to detect known vi ruses.
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`• Reputation Engine - provides reputation-based detection, where fi le hashes, signers and
`other meta-data about the file and the context around its source are compared to our threat
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`intel ligence knowledge base.
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`White Paper Ransomware
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`6
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`FINJAN-JN 045331
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`Case 3:17-cv-05659-WHA Document 369-18 Filed 02/14/19 Page 3 of 3
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`• Behavioral Engine - performs dynamic analysis of the object's behavior in a sandbox
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`environment and applies machine learning models to the observed behavior.
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`• Emulation Engine - emulates fi les containing scripts as an alternative to full behavioral analysis.
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`• Yara Engine - allows application ofYara rules to fi les as well as memory dumps obtained during
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`behavioral analysis.
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`Network Analysis Pipeline
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`Traffic visible to Cyphort also goes through a couple of steps before files are extracted
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`for analysis:
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`• Snort rules - all traffic is subjected to snort rules from Cyphort Labs as well as third
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`party sources.
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`• Chain Heuristics - flags suspicious traffic and submits it to a browserp-based dynamic
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`analysis environment where heuristics rules are applied to identify malicious traffic like
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`exploit kits redirects.
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`Use Cases
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`The detection methods for ransomware are usually tailored to the delivery mechanism. Let's
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`review each delivery mechanism above and discuss what methods of detection Cyphort uses in
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`each case.
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`Email Attachments
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`Cyphort can monitor email traffic using either a journaled account or Bee mailbox. In both cases,
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`Cyphort extracts all email attachments and submits them to SmartCore's Object Analysis Pipeline,
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`where it extracts all links (including links inside attachments) and submits them to SmartCore's
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`reputation engine. Cyphort integrates with Office365 and Gmail to provide seamless remediation
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`capability by blocking or quarantining malicious emails.
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`If ransomware is being delivered via a PDF, Office document, malicious Javascript or
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`executable file attached to an email, Cyphort uses all elements of the Object Analysis Pipeline
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`to identify the threat.
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`Locky was a prominent example of ransomware downloaded by an email attachment. The
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`attachment itself is either a Javascript fi le inside a zip file or a Word document with a VBA macro
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`claiming to be an invoice or a shipment notification.
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`Cyphort detects the Javscript zipped attachments as Exploit.Script.
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`White Paper Ransomware
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`7
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`FINJAN-JN 045332
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