MuddyWater Hackers Using UDPGangster Backdoor to Attack Windows Systems Evading Network Defenses

A sophisticated cyber threat has emerged targeting Windows systems across multiple countries in the Middle East.

UDPGangster, a UDP-based backdoor, represents a dangerous new weapon in the arsenal of the MuddyWater threat group, known for conducting cyber espionage operations throughout the Middle East and neighboring regions.

This malware gives attackers complete remote control over compromised machines, enabling them to execute commands, steal files, and deploy additional malicious software through UDP channels deliberately designed to slip past traditional network security measures.

The threat appears increasingly active, with multiple attack campaigns identified targeting users in Turkey, Israel, and Azerbaijan.

These operations demonstrate a coordinated approach, using malicious Microsoft Word documents embedded with dangerous macros as the primary delivery method.

When victims enable these macros, the backdoor installs silently on their systems, granting attackers unprecedented access to sensitive information and critical infrastructure.

The attacks employ sophisticated social engineering tactics, with phishing emails impersonating government entities.

Notably, one campaign claimed to be from the Turkish Republic of Northern Cyprus Ministry of Foreign Affairs, inviting recipients to an online seminar on presidential elections.

The decoy documents include innocuous-looking information designed to distract users while malicious code executes in the background.

Fortinet security analysts identified and studied multiple UDPGangster campaigns, noting extensive anti-analysis capabilities built into the malware.

These samples incorporate advanced techniques specifically designed to detect and evade virtual environments, sandboxes, and security analysis tools, helping attackers avoid early detection by security researchers and automated systems.

Infection Mechanism and Anti-Analysis Evasion

The infection begins when victims receive phishing emails containing Microsoft Word documents with embedded VBA macros.

Upon opening and enabling the macros, the Document_Open() event automatically triggers, launching a chain of events that installs the backdoor.

The technical infection process is straightforward yet effective. The macro decodes Base64-encoded data from a hidden form field and writes it to C:\Users\Public\ui.txt.

The malware then executes this file using Windows API functions, specifically CreateProcessA, which launches the UDPGangster payload directly into system memory.

UDPGangster establishes persistence by copying itself to %AppData%\RoamingLow as SystemProc.exe, then modifies the Windows registry by adding the malware path to HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders under the Startup value.

This ensures the backdoor automatically runs whenever the victim restarts their computer.

The malware incorporates nine distinct anti-analysis techniques, including debugger detection, CPU environment checks for single-core configurations common in virtual machines, memory and disk size verification, virtual adapter MAC address analysis, hardware inspection through WMI queries, process scanning for virtualization tools, extensive registry examination, sandbox tool detection, and filename verification against known test environments.

After bypassing security analysis, UDPGangster collects system details like computer name, domain information, and OS version, encodes them using ROR-based transformation, and sends this data to command-and-control servers at 157.20.182.75 over UDP port 1269.

While they do so by maintaining the communication that standard network monitoring typically misses.

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