BlueHat v17 || Wannacrypt + Smbv1.0 Vulnerability = One of the Most Damaging Ransomware Attacks in History
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The document summarizes the Wannacrypt + Smbv1.0 ransomware attack, one of the most damaging in history. It began on a Friday in May 2017, infecting over 216,000 machines worldwide in just one day by exploiting an SMB vulnerability. The ransomware used the EternalBlue exploit leaked from the ShadowBrokers to spread rapidly through networks. Microsoft had released a patch for the vulnerability in March 2017 but many systems remained unpatched. The attack was stopped when a researcher registered a domain name hard-coded in the ransomware. The document examines the technical details and impact of the attack, and recommends steps to prevent future ransomware infections like keeping systems updated with the latest security patches.
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BlueHat v17 || Wannacrypt + Smbv1.0 Vulnerability = One of the Most Damaging Ransomware Attacks in History
- 1. Wannacrypt + Smbv1.0 Vulnerability = One of the Most Damaging Ransomware Attacks in History Andrea Lelli – anlelli@microsoft.com
- 2. Introduction • Initial spread and telemetry • The bug • The backdoor • Mitigations • The ransomware • The aftermath • Conclusion
- 3. It began on a Friday • Several organization started reporting massive infections o NHS in UK o Telefonica in Spain o FedEx in US o MegaFon in Russia Overall campaign: • 216k until August (estimated more) • Spanning through all the world
- 4. “Is it worm-able ?” • How does it spread so fast?
- 5. “Is it worm-able ?” YES Source: Packetstorm Security https://packetstormsecurity.com/files/142464/MS17-010.txt
- 6. Timeline of the vulnerability March 14th May 12th April 14th MS17-010 Released ETERNALBLUE leaked, code is publicly available WannaCrypt unleashed May 10th Exploit code wildly adopted (Packetstorm, Exploit DB) January 16th US CERT warns about potential (unconfirmed) SMB vulnerability January 8th ShadowBrokers put stolen tools on sale (750 Bitcoins)
- 7. Initial infection vector ? • Earlier Wannacry found along with Lazarus’ tools • New Wannacry possibly planted by Lazarus actors? • We don‘t know!
- 8. Telemetry • Wannacrypt detections • Distinct machines • First encounters Windows 7
- 9. Cumulative Telemetry • Wannacrypt detections • Distinct machines • First encounters
- 13. The bug Bad integer cast -> buffer overflow ATTR ATTR ATTR ATTR ATTR BUFFER ATTR ATTR ATTRATTR ATTR Original List Size: 0x00010000 Truncated List Size: 0x0000FF5D Updated List size: 0x0001FF5D Excellent article from Viktor Brange: https://blogs.technet.microsoft.com/mmpc/2017/06/16/analysis-of-the-shadow-brokers-release-and-mitigation- with-windows-10-virtualization-based-security/ Unsigned Long Unsigned Short
- 14. The exploit KERNEL MEMORY SMB Spray Trigger … … Ptr SRVNET_CONNECTION … … SRVBUFFER struct HAL MEMORY RWX … Ptr SRVNET_RECEIVE_HANDLER … Shellcode SRVNET_CONNECTION struct Fixed address! Works on Windows 7
- 15. The backdoor (DoublePulsar) Excellent article from Matt Oh: https://blogs.technet.microsoft.com/mmpc/2017/06/30/exploring-the-crypt-analysis-of-the-wannacrypt- ransomware-smb-exploit-propagation/ Step 1: Hook SYSENTER handler What About Patchguard ???
- 16. The backdoor (DoublePulsar) Step 2: SYSENTER hook is executed, Original SYSENTER handler restored Backdoor installed SRV!SrvTransactionNotImplemented (Transaction2->SESSION_SETUP) Hook UnHook Patchguard thread: • Unlikely to spawn when SYSENTER hooked • Does not check for SRV code/ writabe data sections By design, PatchGuard does not catch transient attacks
- 17. Mitigations 1. HAL memory not RWX (DEP, HVCI requires DeviceGuard) 2. HAL memory location randomized (kASLR) 3. Control Flow Guard (optional, requires DeviceGuard) X X X XDoesn’t work on Windows 10 RS1+! X
- 18. Mitigations 1. Hyper Guard – Mitigates MSR writes 2. Legacy dispatch tables made Read Only X X
- 19. More mitigations! In general, several mitigations were introduced in Windows 10 • Controlled Folder Access (CFA) • Access to folders with documents is restricted (hinders ransomware) • Code Integrity Guard (CIG) • Can’t modify executable memory • Arbitrary Code Guard (ACG) • Can’t load or create untrusted executable memory • MemGC • Prevents Use After Free exploitation …and more! (Not all are active by default.)
- 20. The ransomware
- 21. Encryption • Targets wide range of file extensions • Renames encrypted files by adding “.wncry” • Uses AES-128 • One key per file • Encrypted with randomly generated RSA key
- 22. And finally…
- 23. Unusual features • Stops exchange and SQL related processes • Deletes shadow copies / backup catalog • Overwrites original file with junk data • Then deletes it • Writes Gb’s of junk data in temp file • Until < 1Gb remains
- 25. WanaKiwi / WanaDecrypt • Tools for decryption of the files Scans WanaCrypt’s memory for keys • Do they work? If you did not reboot If you did not run other software If you ran WanaKiwi immediately If you are lucky • Too many “if”!
- 26. WanaKiwi / WanaDecrypt IT WORKS! (Wanafork tool can use this) Prime numbers candidates (from memory) This candidate divides malware’s key IN THEORY:
- 27. WanaKiwi / WanaDecrypt IN PRACTICE: • Office • Browser • Outlook • Click WanaCrypt’s interface • Leave it for a couple of hours Unlikely to work
- 28. Worth it? “We have taken measures to blacklist all addresses associated with the WannaCry attackers that are known to the ShapeShift team” Spokesperson from ShapeShift
- 29. Worth it? $ 142,361 $ 300 474 payments 0.2 % of 216000 infected machines (Very rough estimate) "Cyber extortion losses are skyrocketing with ransomware on pace to be a 1 billion dollar business in 2016." The FBI - as reported by CNN
- 30. Is it still alive? Alas, yes! (Not just Wannacrypt) DoublePulsar detections by platform per day
- 31. Is it still alive? DoublePulsar distribution
- 32. Copycats • UIWIX • Ransomware: encrypts files • File-less: only resides in memory • Steals information • ALDYKUZZ • Monero coin miner • PETYA • Encrypts Files and MFT • BADRABBIT (PETYA variant) • Leverages ETERNALROMANCE
- 33. Who?
- 35. Conclusion • Install security updates! • Disable unnecessary / legacy features • Block inbound/outbound SMB traffic to your network if possible • Do not pay cybercriminals • Do not delete the encrypted files • Respond quickly and isolate infected machines • Use Windows 10!