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

I will be teaching next: Reverse-Engineering Malware: Malware Analysis Tools and Techniques - SANS Amsterdam October 2020