CYFIRMA identified a targeted multi-stage malware campaign attributed to Transparent Tribe (APT36) that uses socially engineered ZIP archives, deceptive shortcut files, and a macro-enabled PowerPoint add-in to deliver a remote access trojan and maintain stealth. The final payload hsuzoiaisaacrhy.exe establishes raw TCP C2 to 93.127.130.89 with a fallback domain and supports screenshotting, live screen monitoring, file exfiltration, and persistence mechanisms. #APT36 #hsuzoiaisaacrhy
Keypoints
- Transparent Tribe (APT36) deployed a socially engineered ZIP archive masquerading as examination documents containing a deceptive .lnk shortcut and a macro-enabled PowerPoint add-in (Brief.ppam) to initiate the infection chain.
- The .lnk shortcut executes a hidden batch script (myscsd.bat) that stages files in a hidden folder (~), copies decoy PDFs to ProgramData, removes Mark-of-the-Web, creates a hard link in AppData, and launches a linked executable to run the RAT.
- The PowerPoint add-inâs VBA macro auto-executes (Auto_Open), self-copies, renames the add-in as a ZIP, extracts embedded OLE objects, reconstructs an OS-appropriate PE payload, and deploys a decoy document to mask activity.
- The final .NET executable (hsuzoiaisaacrhy.exe) contains a hardcoded C2 indicator (IP 93.127.130.89 and fallback domain sharemxme126.net), establishes raw TCP C2, implements persistence via Startup registry, and includes extensive RAT capabilities (file transfer, remote execution, screenshots, live streaming).
- Attackers used multiple defense-evasion techniques including string and code obfuscation, junk code insertion, randomized names, hidden staging directories, Mark-of-the-Web removal, hard links, and a self-deleting cleanup executable (fimsrwvar.exe) to hinder analysis and forensic recovery.
- Observed IOCs include multiple file hashes (MD5 and SHA-256), filenames used in lures and payloads, an active C2 IP, and an embedded fallback domain; recommended mitigations include email gateway defenses, macro restrictions, EDR monitoring, and behavioral detection for the described execution chain.
MITRE Techniques
- [T1566.001 ] Phishing: Spearphishing Attachment â Initial delivery via a socially engineered ZIP archive masquerading as examination-related documents (âmalicious ZIP archive masquerading as examination-related documentsâ).
- [T1204.002 ] User Execution: Malicious File â Victim interaction with deceptive double-extension shortcut files triggers execution (âdeceptive double-extension shortcut file (e.g., Approved Documents 2026.pdf.lnk)â).
- [T1059 ] Command and Scripting Interpreter â Use of batch scripts and PowerShell to stage and execute payloads (â%comspec% /c start /MIN ~myscsd.bat.â).
- [T1059.003 ] Command and Scripting Interpreter: Windows Command Shell â The .lnk invokes cmd to run a minimized batch file to hide activity (â%comspec% /c start /MIN ~myscsd.bat.â).
- [T1059.005 ] Command and Scripting Interpreter: Visual Basic â VBA macros auto-execute and perform extraction and reconstruction (âAuto_Open() function when the malicious PowerPoint add-in is opened.â).
- [T1203 ] Exploitation for Client Execution â Macro-driven extraction and reconstruction of embedded OLE objects into a runnable executable (âreconstructs the malicious executableâ).
- [T1547.001 ] Boot or Logon Autostart Execution: Registry Run Keys â Malware establishes persistence by adding itself to the userâs startup registry key (âestablishes persistence by adding itself to the current userâs Windows startup registry key.â).
- [T1546 ] Event Triggered Execution â Use of Office add-in auto-execution and file shortcuts to trigger payload execution (âAuto_Open() function when the malicious PowerPoint add-in is opened.â).
- [T1543 ] Create or Modify System Process â Launching linked executables and creating processes to run payload components (âlaunches the linked executable using startâ).
- [T1027 ] Obfuscated Files or Information â Use of string obfuscation, randomized names, and junk code insertion to hinder analysis (âobfuscation and junk code insertionâ).
- [T1564 ] Hide Artifacts â Use of hidden staging directory (â~â) and hidden attributes to conceal files (âa hidden folder named â~ââ).
- [T1036 ] Masquerading â Deceptive filenames and double extensions used to masquerade malicious files as legitimate documents (âdeceptive double-extension filename, âApproved Documents 2026.pdf.lnk,ââ).
- [T1553.005 ] Mark-of-the-Web Bypass â PowerShell Unblock-File is used to remove Mark-of-the-Web and allow execution without warning (âPowerShell Unblock-File to remove the âMark of the Webâ security flagâ).
- [T1140 ] Deobfuscate/Decode Files or Information â Macro renames the add-in as a ZIP and extracts embedded objects to reconstruct payloads (âcopies itself and renames the file as a ZIP archiveâŚextracts embedded OLE objectsâ).
- [T1070.004 ] File Deletion â Anti-forensic self-deleting behavior via a generated executable that removes .exe files and then deletes itself (âSelf-deleting executable (fimsrwvar.exe) to remove tracesâ).
- [T1012 ] Query Registry â Malware checks and updates registry values as part of persistence logic (âchecks the existing value and updates it if necessaryâ).
- [T1033 ] System Owner/User Discovery â Use of environment variables and user profile paths to create per-user staging directories (âuses the %USERPROFILE% environment variableâ).
- [T1057 ] Process Discovery â Ability to enumerate and monitor running processes on the infected host (âProcess enumerationâ).
- [T1082 ] System Information Discovery â Macro checks OS version to select compatible payload variants (âdetect the operating system versionâ).
- [T1083 ] File and Directory Discovery â Drive and filesystem enumeration to locate targets and stage files (âDrive enumerationâ / âFile system browsingâ).
- [T1087 ] Account Discovery â Capabilities to enumerate accounts for situational awareness (âAccount Discoveryâ).
- [T1518 ] Software Discovery â Enumeration of installed software for targeting and evasion (âSoftware Discoveryâ).
- [T1135 ] Network Share Discovery â Ability to discover network shares within the environment (âNetwork Share Discoveryâ).
- [T1113 ] Screen Capture â Capability to capture screenshots and send them to the operator (âScreenshot captureâ).
- [T1005 ] Data from Local System â Remote file exfiltration support (chunked upload) from local file system (âRemote file exfiltration (chunked upload)â).
- [T1071 ] Application Layer Protocol â C2 command exchange over network channels with hardcoded commands in the binary (âMultiple commands are hardcoded within the binary, which are issued by the server to trigger specific actionsâ).
- [T1095 ] Non-Application Layer Protocol (Raw TCP) â Malware establishes a raw TCP connection directly to the C2 server for command and control (âestablishes a direct raw TCP connection to the command-and-control (C2) serverâ).
- [T1573 ] Encrypted Channel â C2 communication design includes channel protections for command/response (binary lists network indicator and fallback domain â93.127.130.89?sharemxme126.netâ).
- [T1041 ] Exfiltration Over C2 Channel â Exfiltration of data and command results back to operators over the C2 channel (âexecution results are transmitted back over the same channelâ / âfile upload (chunked exfiltration)â).
Indicators of Compromise
- [File Names ] lure and payload names used in the campaign â Approved Documents 2026.pdf.lnk, Brief.ppam (macro-enabled add-in).
- [Executable Names ] final payload and cleanup binary â hsuzoiaisaacrhy.exe (final RAT), fimsrwvar.exe (self-deleting cleanup executable).
- [Script Names ] execution scripts used by shortcuts â myscsd.bat (batch script invoked by .lnk).
- [MD5 Hashes ] MD5 hashes of delivered components â Brief.ppam ff1a302651019277d90c814c2e0940ec, Approved Documents 2026.pdf.lnk 81d97473b2b87310b2caf3376341fba6 (and 1 more MD5 hash).
- [SHA-256 Hashes ] malware component SHA-256 indicators (blocking/hunting) â 34412e765822cf3fb32a5a5c9866fb29a9b98d627b4d9a3275fd3e754cf8e360, 7b4e1670930ec33a673d9b32454f67f28af73a89958fcaba4b24ac2c799b1af1 (and 2 more hashes).
- [IP Address ] active command-and-control endpoint â 93.127.130.89 (hardcoded C2 IP observed as active at analysis time).
- [Domain ] embedded fallback domain for C2 continuity â sharemxme126.net (fallback domain embedded in binary alongside IP).
- [YARA Rule ] detection signature provided for integration â APT36_Macro_Embedded_Malware_Campaign_IOC (includes hashes and C2 IP for detection and blocking).