Supply Chain Compromise Leads to Trojanized Installers for Notezilla, RecentX, Copywhiz

最后更新于2024年6月28日星期五18:00:03 GMT

The following Rapid7 analysts contributed to this research: Leo Gutierrez, Tyler McGraw, Sarah Lee, and Thomas Elkins.

Executive Summary

On Tuesday, June 18th, 2024, Rapid7 initiated an investigation into suspicious activity in a customer environment. Our investigation identified that the suspicious behavior was emanating from the installation of Notezilla, a program that allows for the creation of sticky notes on a Windows desktop. Installers for Notezilla, 以及RecentX和Copywhiz等工具, are distributed by the India-based company Conceptworld at the official domain conceptworld[.]com. After analyzing the installation packages for all three programs, Rapid7 discovered that the installers had been trojanized to execute information-stealing malware that has the capability to download and execute additional payloads.

Disclosure

On Monday, June 24th, 2024, Rapid7 contacted Conceptworld to disclose the backdoored installers being hosted on conceptworld[.]com in accordance with Rapid7的漏洞披露策略. Within 12 hours, Conceptworld confirmed and remediated the issue by removing the malicious installers from conceptworld[.]com 把它们换成合法的，有签名的副本. Rapid7 is grateful to Conceptworld for their prompt action on this issue.

Overview

Conceptworld is an India-based company offering three different software products: Notezilla, which allows users to create sticky notes on a Windows desktop; RecentX, which stores recently used files/applications/clipboard data; and Copywhiz, 这改进了文件复制和备份操作. 官方提供免费试用下载 conceptworld[.]com site for each software package.

所提供的安装包 conceptworld[.]com at the time of investigation, however, 与合法安装程序一起执行恶意软件, were not signed, 并且与下载页面上声明的文件大小不匹配. The differences in the file sizes are due to the malware and its dependencies, which increases the size of the compromised installation packages.

The malware Rapid7 observed contains the functionality to steal browser credentials and crypto currency wallet information, 记录剪贴板内容和按键, 下载并执行额外的有效载荷. After infecting a system, the malware persists via a scheduled task that executes the primary payload every three hours.

基于提交给VirusTotal的文件, the malicious copies of the installers have existed since early June of 2024. 木马安装程序提供的恶意软件有效载荷, however, seem to belong to a nameless malware family that has been in distribution since at least January of 2024. Rapid7内部将这个恶意软件家族称为 dllFake because of the naming scheme used for several of the malware payloads.

Technical analysis

要深入了解恶意软件的有效载荷, we will analyze the malicious installer that was served for Notezilla.

Initial Access

Rapid7 determined that trojanized installers for the 32-bit and 64-bit versions of Notezilla, Copywhiz, and RecentX were, at the time of investigation, 由官方网站提供服务 conceptworld[.]com. Any users searching for this software via a popular search engine at the time were most likely to find the official domain as the first result, 然后引导他们下载恶意软件吗.

Execution

The installer served by conceptworld[.]com 在调查的时候Notezilla是 NotezillaSetup.exe, which, based on static analysis, is packed using software called Smart Install Maker(5.04).

Figure 1. Software Properties of NotezillaSetup.exe.

Using the sim_unpacker plugin for the tool UniExtract2, we were able to unpack and acquire most of the contents of the installation package, 例如嵌入的文件和配置信息. The configuration file contains references to the legitimate software installer for Notezilla, which is dropped into %TEMP% during execution, and multiple files that are dropped into the installation directory (i.e., staging folder) % LOCALAPPDATA % \ WindowsApps \ \微软 during execution.

Figure 2. 使用sim-unpacker工具输出.

Figure 3. Contents of installer.config.

Once executed, NotezillaSetup.exe will then execute the file dllCrt32.exe from the staging directory % LOCALAPPDATA % \ WindowsApps \ \微软 via a WINAPI call to ShellExecuteA with the verb open. A second call is then made to ShellExecuteA to execute the file NotezillaSetup.exe，合法安装程序的副本，来自 %TEMP%. As a result, the only thing seen by the end user after initial execution is the installation window pop-up for the legitimate installer, prompting the user to proceed with the installation process for Notezilla.

Figure 4. Typical Process Tree for Initial Execution of the Trojanized Installer.

Figure 5. The User’s View after the Infection has Already Begun in the Background.

The file dllCrt32.exe is a relatively small (~10KB) program that only serves as a wrapper to call CreateProcessA to execute the file dllCrt.bat.

Figure 6. The Contents of dllCrt.bat.

The batch file dllCrt.bat 然后创建一个名为?的隐藏计划任务 Check dllHourly32 using schtasks.exe and an XML file that was previously dropped into the staging directory at % LOCALAPPDATA % \ \ WindowsApps \ dllCrt微软.xml. The scheduled task Check dllHourly32 will then execute the file % LOCALAPPDATA % \ \ WindowsApps \ dllBus32微软.exe 最初创建后每三小时一次, which means that the primary malware payload will not be executed until at least three hours after the user originally executed the trojanized installer.

Figure 7. Command Line Assembly within dllBus32.exe.

When dllBus32.exe 执行时，它还用作调用 CreateProcessA, though it initially retrieves several important command line parameters. 首先，调用CRT库函数 sprintf 连接一个硬编码的IPv4地址. Then, a second call to sprintf concatenates the assembled IPv4 address with several other arguments to be passed to the batch file dllBus.bat. Finally, CreateProcessA 用完全组装的命令行调用.

Figure 8. The Initial Lines of dllBus.bat.

的命令行参数 dllBus.bat via dllBus32.exe contain an IPv4 address, an SFTP port, ZIP存档有效负载的密码, two sets of SFTP credentials, and the staging directory where the majority of the malware’s files are located.

The batch file dllBus.bat contains functionality to facilitate the theft of information from Google Chrome, Mozilla Firefox, 以及多种加密货币钱包. The copy of curl.exe dropped by the installer is also used to connect to a list of command-and-control (C2) addresses hosting SFTP servers. The curl commands are used to download an updated list of C2 addresses, 以明文形式存储在文件中 dll_srv.txt, and to download and execute additional payloads saved within encrypted ZIP archives named Updt.zip, Apps.zip, and BB.zip. The batch script will also attempt to compress all files on the infected system that have specific file extensions and exist in directories that are not on a hardcoded blacklist (for exfiltration). 所有被盗数据最终都使用 7z.exe 并使用curl直接上传到所选的C2 SFTP服务器.

The payloads Apps.zip and Updt.zip 创建的可执行文件 PyInstaller, which means the original Python script used to create the executables can be recovered trivially using a publicly available extractor. The payload dllChrome32.exe, contained within Updt.zip, is used to facilitate theft of credentials from Google Chrome’s database that are then saved into the file %TEMP%\chrm.txt 格式为:URL，用户名，密码.

Figure 9. Primary Functionality of dllChrome32.exe.

The payloads dllTemp32.exe and dllCache32.exe stored within Apps.zip contain a clipboard stealer and a keylogger, where the results are saved to the files cl.txt and kl.txt，分别在暂存目录at % LOCALAPPDATA % \ WindowsApps \ \微软.

Figure 10. 复制到剪贴板的所有数据被转储到 cl.txt when dllTemp32.exe is Running.

Figure 11. dllCache32.exe Logs Keystrokes to kl.txt when Running.

Rapid7 did not observe any of the identified SFTP servers hosting the third payload, BB.zip，在写作的时候，虽然内容 dllBus.bat 指示它包含可执行文件 srvBus32.exe and srvCrt32.exe，其功能未知.

Mitigation Guidance

Rapid7 recommends verifying the file integrity of freely available software. Check that the file hash and properties of the downloaded file(s) match those provided by the official distributor and/or that they contain a valid and relevant signature. The malicious installers observed in this case are unsigned and have a file size that is inconsistent with copies of the legitimate installer, 就像官方下载页面上写的那样.

If an installer for Notezilla, RecentX, Copywhiz在一个月内在一个系统上执行过, Rapid7 recommends checking for signs of compromise due to the malicious installers detailed in this blog. The primary indicators of infection include the hidden scheduled task Check dllHourly32 and a persistent running instance of the Windows Command Prompt, cmd.exe，使出站网络连接通过 curl.exe.

如果发现妥协的证据, Rapid7 recommends re-imaging affected systems to a known good baseline to eradicate any changes made by the malware.

Rapid7 Customers

InsightIDR, Managed Detection and Response, and Managed Threat Complete customers have existing detection coverage through Rapid7's expansive library of detection rules. Rapid7 recommends installing the Insight agent on all applicable hosts to ensure visibility into suspicious processes and proper detection coverage. Below is a non-exhaustive list of detections that are deployed and will alert on behavior related to this activity:

MITRE ATT&CK Techniques

Indicators of Compromise

Network-Based Indicators (NBIs)

Host-Based Indicators (HBIs)