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InfoSec Handlers Diary Blog

For an updated summary, see: WannaCry/WannaCrypt Ransomware Summary

For a few hours, bad news are spreading quickly about a massive wave of infections by a new ransomware called "WannaCry". We are still trying to collect more information about it. It seems that 45K attacks were detected from 74 differents countries:

(Source: MalwareTech)

Big targets have been telecom operators (ex: Telefonica in Spain) and hospitals in UK. Once the malware has infected a computer, it spreads across the network looking for new victims using the SMB protocol.

The ransomware uses the Microsoft vulnerability MS17-10[1]. (This vulnerability was used by ETERNALBLUE[2])

Here are some IOC's that we already collected:

SHA256:

• 09a46b3e1be080745a6d8d88d6b5bd351b1c7586ae0dc94d0c238ee36421cafa
• 24d004a104d4d54034dbcffc2a4b19a11f39008a575aa614ea04703480b1022c
• 2584e1521065e45ec3c17767c065429038fc6291c091097ea8b22c8a502c41dd
• 2ca2d550e603d74dedda03156023135b38da3630cb014e3d00b1263358c5f00d
• 4a468603fdcb7a2eb5770705898cf9ef37aade532a7964642ecd705a74794b79

SHA1:

• 45356a9dd616ed7161a3b9192e2f318d0ab5ad10
• 51e4307093f8ca8854359c0ac882ddca427a813c

MD5:

• 509c41ec97bb81b0567b059aa2f50fe8
• 7bf2b57f2a205768755c07f238fb32cc
• 7f7ccaa16fb15eb1c7399d422f8363e8

File extension: .wncry

Ransomware notification: @Please_Read_Me@.txt

Emerging threats has an IDS rule that catches the ransomware activity: (ID: 2024218)

alert tcp $HOME_NET 445 -> any any (msg:"ET EXPLOIT Possible ETERNALBLUE MS17-010 Echo Response"; flow:from_server,established; content:"|00 00 00 31 ff|SMB|2b 00 00 00 00 98 07 c0|"; depth:16; fast_pattern; content:"|4a 6c 4a 6d 49 68 43 6c 42 73 72 00|"; distance:0; flowbits:isset,ETPRO.ETERNALBLUE; classtype:trojan-activity; sid:2024218; rev:2;)

Until now, the best protection is of course to patch your systems as soon as possible and keep your users aware of the new ransomware campaign to preven them to open suspicious emails/files.

[1] https://technet.microsoft.com/en-us/library/security/ms17-010.aspx
[2] https://isc.sans.edu/forums/diary/ETERNALBLUE+Windows+SMBv1+Exploit+Patched/22304/

We will update this diary with more information if available. 

Xavier Mertens (@xme)
ISC Handler - Freelance Security Consultant
PGP Key