Rewterz Threat Advisory – SamSam Ransomware launches cyber-attacks worldwide

NCCIC and FBI have issued a threat alert about a ransomware called SamSam. It encrypts network systems without requiring user authentication.

IMPACT:  MEDIUM

PUBLISH DATE:  04-December-2018

OVERVIEW

The SamSam actors targeted multiple industries in the United States and Internationally, launching network-wide attacks against organizations to secure huge amounts of ransom payments. Organizations that provide services are primary target as they’re likely to produce speedy ransom in order to have their systems decrypted and their services restored.

ANALYSIS

The actors exploit Windows servers to access victim’s network and infect all reachable hosts. Beginning in 2016, cyber actors used the JexBoss Exploit Kit to access vulnerable JBoss applications. It was also discovered that these cyber actors use Remote Desktop Protocol (RDP) to gain persistent access to victims’ networks. Usually, attackers use stolen login credentials or Brute Force attacks to access the network. Therefore, RDP intrusion detection becomes hard because the malware enters through an authenticated access point.

Once successful access to a target network is achieved, the SamSam threat actors elevate their privileges to administrator rights and deploy malware on the server. An executable file is then run without needing authentication from the user. The executables then encrypt target computers. Ransom notes are found on the encrypted computers with instructions that direct victims to contact through a Tor hidden service site.

Once the ransom is paid in bitcoins, victims receive links to download cryptographic keys to decrypt their network.

Analysts believe that these stolen RDP credentials were purchased from known darknet marketplaces prior to SamSam’s attack. Other suspicious activity unrelated to SamSam found on victim networks indicates that the credentials had been stolen and sold to multiple threat entities.

INDICATORS OF COMPROMISE

SamSam is a variety of ransomware based on the .NET framework. Four different variants of the ransomware have been retrieved. Following are the indicators of compromise that were submitted for analysis of each of the four variants of SamSam ransomware.

SamSam1

Analysis indicates that these files are ransomware.

• 5d65ebdde1aef8f23114f95454287e7410965288f144d880ece2a2b8c3128645 (prelecturedexe[.]exe)
• d8d919d884b86e4d5977598bc9d637ed53e21d5964629d0427077e08ddbcba68 (proteusdlll[.]dll)

SamSam2

• 2b06d2abc87f51aa7b8451da16270003ceba57184b0dd5f244670873409c75b9 (winnetuse[.]exe)
• 427091e1888c2bf1f2e11a1010b3ab6c8634eda4ddc34d37202d401fbaa8989d (ss2[.]exe)
• 594b9b42a2d7ae71ef08795fca19d027135d86e82bc0d354d18bfd766ec2424c (ss2[.]stubbin)
• a660cc6155b307c0957c4c6ea119a295a852d28097196d85f00f5517944a3dcb (SORRY-FOR-FILES[.]html)
• bc53f513df363dd999ac855b53831b3b31ac5516a4bf8f324489710cf06955f0 (g04inst[.]bat)
• da9c2ecc88e092e3b8c13c6d1a71b968aa6f705eb5966370f21e306c26cd4fb5 (sdgasfse[.]dll)

Domains:

• jcmi5n4c3mvgtyt5[.]onion

SamSam3

These files are designed to encrypt a victim’s system files for a ransom payment.

• 036071786d7db553e2415ec2e71f3967baf51bdc31d0a640aa4afb87d3ce3050 (samsam[.]exe)
• 0f2c5c39494f15b7ee637ad5b6b5d00a3e2f407b4f27d140cd5a821ff08acfac (samsam[.]exe)
• 32445c921079aa3e26a376d70ef6550bafeb1f6b0b7037ef152553bb5dad116f (selfdel[.]exe)
• 45e00fe90c8aa8578fce2b305840e368d62578c77e352974da6b8f8bc895d75b (samsam[.]exe)
• 553967d05b83364c6954d2b55b8cfc2ea3808a17c268b2eee49090e71976ba29 (553967d05b83364c6954d2b55b8cfc…)
• 58ef87523184d5df3ed1568397cea65b3f44df06c73eadeb5d90faebe4390e3e (samsam[.]exe)
• 6245a51e78526c25510d0aa0909576119fdf0244619f670036538063b88f1c21 (HELP_DECRYPT_YOUR_FILES[.]html)
• 6bc2aa391b8ef260e79b99409e44011874630c2631e4487e82b76e5cb0a49307 (samsam[.]exe)
• 7aa585e6fd0a895c295c4bea2ddb071eed1e5775f437602b577a54eef7f61044 (samsam[.]exe)
• 89b4abb78970cd524dd887053d5bcd982534558efdf25c83f96e13b56b4ee805 (samsam[.]exe)
• 939efdc272e8636fd63c1b58c2eec94cf10299cd2de30c329bd5378b6bbbd1c8 (samsam[.]exe)
• 946dd4c4f3c78e7e4819a712c7fd6497722a3d616d33e3306a556a9dc99656f4 (samsam[.]exe)
• 979692a34201f9fc1e1c44654dc8074a82000946deedfdf6b8985827da992868 (samsam[.]exe)
• 97d27e1225b472a63c88ac9cfb813019b72598b9dd2d70fe93f324f7d034fb95 (del[.]exe)
• a763ed678a52f77a7b75d55010124a8fccf1628eb4f7a815c6d635034227177e (samsam[.]exe)
• e682ac6b874e0a6cfc5ff88798315b2cb822d165a7e6f72a5eb74e6da451e155 (samsam[.]exe)
• ffef0f1c2df157e9c2ee65a12d5b7b0f1301c4da22e7e7f3eac6b03c6487a626 (samsam[.]exe)

Domains:

• anonyme[.]com
• evilsecure9[.]wordpress[.]com
• followsec7[.]wordpress[.]com
• key88secu7[.]wordpress[.]com
• keytwocode[.]wordpress[.]com
• lordsecure4u[.]wordpress[.]com
• payforsecure7[.]wordpress[.]com
• secangel7d[.]wordpress[.]com
• union83939k[.]wordpress[.]com
• zeushelpu[.]wordpress[.]com

SamSam4

• 738c95f5bfe63a530b200a0d73f363d46c5671c1fcbb69c217e15a3516501a86 (mswinupdate[.]exe)
• 9b23bfc35b18ed80104c496b2aa722b3e56ff9ceb9dae60d1aff7230321c1d12 (ClassLibrary1[.]dll)
• bbd4102fe25e73c0815d0c020d60d47dbbfbe79ef1e490e7b4f97640dd932b58 (g04inst[.]bat)

MITIGATIONS

DHS and FBI recommend that users and administrators consider using the following best practices to strengthen the security posture of their organization’s systems. Administrators should review configuration changes prior to implementation to avoid any inconvenience or damage.

• Audit your network for systems that use RDP for remote communication. Disable unneeded services and keep systems updated to patched versions. (Make sure patches do not affect system processes).
• Cloud-based virtual machine instances with public IPs must not have any open RDP ports, especially port 3389, unless there is a valid business reason to keep open RDP ports. (Place any system with an open RDP port behind a firewall and require users to use a virtual private network (VPN) to access that system.)
• Enable strong passwords and account lockout policies to defend against brute force attacks and avoid credentials theft.
• Secure accounts using two-factor or multi-factor authentication.
• Regularly apply system and software updates.
• Maintain a good back-up strategy.
• Enable logging and ensure that logging mechanisms capture RDP logins. Store logs of at least 90 days and review them regularly to detect intrusion attempts.
• When creating cloud-based virtual machines, adhere to the cloud provider’s best practices for remote access.
• Ensure that third parties that require RDP access follow internal policies on remote access.
• Minimize network exposure for all control system devices. Where possible, disable RDP on critical devices.
• Regulate and limit external-to-internal RDP connections. When external access to internal resources is required, use secure methods such as VPNs.
• Restrict users’ ability (permissions) to install and run unwanted software applications.
• Scan for and remove suspicious email attachments; ensure the scanned attachment is its “true file type” (i.e., the extension matches the file header).
• Disable file and printer sharing services. If these services are required, use strong passwords or Active Directory authentication.

If you think you’re the victim of a cyber-attack, immediately send an e-mail to soc@rewterz.com.