Increased Truebot Activity Infects U.S. and Canada Based Networks

Fortify Security Team
Jul 14, 2023

The Cybersecurity and Infrastructure Security Agency (CISA), the Federal Bureau of Investigation (FBI), the Multi-State Information Sharing and Analysis Center (MS-ISAC), and the Canadian Centre for Cyber Security (CCCS) are releasing this joint Cybersecurity Advisory (CSA) in response to cyber threat actors leveraging newly identified Truebot malware variants against organizations in the United States and Canada. As recently as May 31, 2023, the authoring organizations have observed an increase in cyber threat actors using new malware variants of Truebot (also known as Silence.Downloader). Truebot is a botnet that has been used by malicious cyber groups like CL0P Ransomware Gang to collect and exfiltrate information from its target victims.

Previous Truebot malware variants were primarily delivered by cyber threat actors via malicious phishing email attachments; however, newer versions allow cyber threat actors to also gain initial access through exploiting CVE-2022-31199—(a remote code execution vulnerability in the Netwrix Auditor application), enabling deployment of the malware at scale within the compromised environment. Based on confirmation from open-source reporting and analytical findings of Truebot variants, the authoring organizations assess cyber threat actors are leveraging both phishing campaigns with malicious redirect hyperlinks and CVE-2022-31199 to deliver new Truebot malware variants.

Read the associated Malware Analysis Report: MAR-10445155-1.v1 Truebot Activity Infects U.S. and Canada Based Networks
For a downloadable copy of IOCs in .xml and .json format, see:

Associated Delivery Vectors and Tools

Truebot has been observed in association with the following delivery vectors and tools:

Raspberry Robin (Malware)

Raspberry Robin is a wormable malware with links to other malware families and various infection methods, including installation via USB drive [T1091].[5] Raspberry Robin has evolved into one of the largest malware distribution platforms and has been observed deploying Truebot, as well as other post-compromise payloads such as IcedID and Bumblebee malware. With the recent shift in Truebot delivery methods from malicious emails to the exploitation of CVE-2022-31199, a large number of Raspberry Robin infections have leveraged this exploitable CVE.

Flawed Grace (Malware)

FlawedGrace is a remote access tool (RAT) that can receive incoming commands [T1059] from a C2 server sent over a custom binary protocol [T1095] using port 443 to deploy additional tools [T1105]. Truebot malware has been observed leveraging (and dropping) FlawedGrace via phishing
campaigns as an additional payload [T1566.002]. Note: FlawedGrace is typically deployed minutes after Truebot malware is executed.

Cobalt Strike (Tool)

Cobalt Strike is a popular remote access tool (RAT) that cyber threat actors have leveraged—in an observable manner—for a variety of post-exploitation means. Typically a few hours after Truebot’s execution phase, cyber threat actors have been observed deploying additional payloads containing Cobalt Strike beacons for persistence and data exfiltration purposes [T1059]. Cyber threat actors use Cobalt Strike to move laterally via remote service session hijacking [T1563.001][T1563.002], collecting valid credentials through LSASS memory credential dumping, or creating local admin accounts to achieve pass the hash alternate authentication [T1003.001][T1550.002].

Teleport (Tool)

Cyber threat actors have been observed using a custom data exfiltration tool, which Talos has named “Teleport.”[2] Teleport is known to evade detection  during data exfiltration by using an encryption key hardcoded in the binary and a custom communication protocol [T1095] that encrypts data using advanced encryption standard (AES) and a hardcoded key [T1048][T1573.002]. Furthermore, to maintain its stealth, Teleport limits the data it collects and syncs with outbound organizational data/network traffic [T1029][T1030].

Truebot Malware Indicators of Compromise (IOCs)

Truebot IOCs from May 31, 2023, contain IOCs from cyber threat actors conducting Truebot malspam campaigns. Information is derived from a trusted third party, they observed cyber threat actors from 193.3.19[.]173 (Russia) using a compromised local account to conduct phishing campaigns on May 23, 2023 and spread malware through: https[:]//snowboardspecs[.]com/nae9v, which then promptly redirects the user to: https://www.meditimespharma[.]com/gfghthq/, which a trusted third party has linked to other trending Truebot activity.

After redirecting to https://www.meditimespharma[.]com/gfghthq/, trusted third parties have observed, the cyber threat actors using Truebot to pivot to https://corporacionhardsoft[.]com/images/2/Document_16654.exe, which is a domain associated with snowboardspecs[.]com. This malicious domain has been linked to UNC4509, a threat cluster that has been known to use traffic distribution systems (TDS) to redirect users to either a benign or malicious website to facilitate their malicious phishing campaigns in May 2023.

According to trusted third parties, the MD5 Hash: 6164e9d297d29aa8682971259da06848 is downloaded from[.]exe and has been flagged by numerous security vendors, as well as is linked to UNC4509 Truebot campaigns. Note: These IOCs are associated with Truebot campaigns used by Graceful Spider to deliver FlawedGrace and LummaStealer payloads in May of 2023.

After Truebot is downloaded, the malware copies itself to C:\Intel\RuntimeBroker.exe and—based on trusted third party analysis—is linked to[.]php (which is linked to 45.182.189[.]71 (Panama) and is associated with other trending Truebot malware campaigns from May 2023).


Recent Posts

July 17, 2023

Title: Thousands of Images on Docker Hub Leak Auth Secrets, Private Keys Date Published: July 16, 2023 Excerpt: “Researchers at the RWTH Aachen University...

July 14, 2023

Title: Indexing Over 15 Million WordPress Websites with PWNPress Date Published: July 14, 2023 Excerpt: “Sicuranex’s PWNPress platform indexed over 15 million WordPress websites, it collects data...

Critical Patches Issued for Microsoft Products, July 11, 2023

Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution in the context of the logged on user. Depending on the privileges associated with the user, an attacker could then install programs;...