Monday, November 4, 2024
HomeBackdoorTA505 APT Hackers Launching ServHelper Backdoor Malware via Weaponized Excel Documents

TA505 APT Hackers Launching ServHelper Backdoor Malware via Weaponized Excel Documents

Published on

Malware protection

Well-Known and advanced threat actors groups TA505 APT distributing a new variant of ServHelper malware that distributed via weaponized Excel 4.0 macro to open a backdoor & steal sensitive information from infection system.

TA505 threat actors associated with various high profile cyber attackers including infamous Dridex banking trojan and Locky ransomware, delivered through malicious email campaigns.

TA505 group mainly targeting various institutions and organizations including banks, retail businesses, and restaurants.

- Advertisement - SIEM as a Service

In this case, Excel 4.0 macro Dropper employed by an attacker to deliver the ServHelper Backdoor and the payload legitimately singed with a valid digital signature to evade the detection.

ServHelper Malware Infection Process

Initially malicious Excel sheet being delivered via malspam emails, once the victims open the document, Excel 4.0 macro is executed and its calls the msiexec.exe in order to download and execute the ServHelper payload.

ServHelper installer singed with a valid digital signature and the The certificate used to sign the malware was issued to “MASLAK LTD” of Uxbridge.

According to the Deep Instinct research, “Once the dropped payload is executed, it will drop a DLL file contained in the installer to \%TEMP%\xmlparse.dll, and use rundll32.exe to call the DLL’s exported function “sega”.

The malware will then write a base64 encoded PowerShell script (which is contained in xmlparse.dll as a resource) to \%TEMP%\enu1.ps1 and execute it.”

Later the malware write the base64 encoded PowerShell script for
reconnaissance purposes, as well as it checks if a machine is part of a domain and if the user has Admin privileges or is part of the Admin Group.


ServHelper attack flow

Finally, ServHelper communicates with its C2 to receive the following command from the attacker,

  • shell – execute a shell (cmd.exe)command and return its output
  • loaddll –download a DLL file and load it using rundll32.exe
  • persist – write an auto-run registry entry at HK_CU\Software\Microsoft\Windows\CurrentVersion\Run\ as “Intel Protect”, returns “persistence established” if successful.
  • slp – enter sleep mode
  • selfkill – remove the malware from the infected machine

“TA505 is a highly advanced global threat actor. It employs a vast array of sophisticated, constantly developed malware for different purposes, for which it exploits the most recently discovered and publicized weak points.” Deep instinct said.

Indicator of Compromise

Excel 4.0 macro Dropper

63522e00181e6b8d9ae8bfd51f7df8f8ebd0f42323e22047269df9c7a71c9b6d

NSIS Payloads

e0323064f2561ae02f9efae418aeaf433b3fe0e6e3a640a9c46ec404d4563de1 302aa690ae61d36769ecdaa3d23ac8fb167e80aed2fe5dbc8938f7b75c655a01

ServHelper core DLL

bee3b2710f7e874ce05e6b8b45cc20e021b9c00ee337238598e71e7315128333 2f827084ecc300aea0c84cba8872c9a34e6afce56eea454d74f4dd3144301a2d

Encoded reconnaissance PowerShell script

da7465f14cd8a934668f59974e8836e02a9b1ff948bfe964040b840ab61697dc da7465f14cd8a934668f59974e8836e02a9b1ff948bfe964040b840ab61697dc

You can follow us on LinkedinTwitterFacebook for daily Cybersecurity updates also you can take the Best Cybersecurity courses online to keep your self-updated.

Also Read:

New Android Malware “BasBanke” Steal Financial Data Such as Credentials & Credit/Debit Card Numbers

New Credential Stealer Malware Campaign Targets Hundreds of Companies Abusing Legitimate Tools

Balaji
Balaji
BALAJI is an Ex-Security Researcher (Threat Research Labs) at Comodo Cybersecurity. Editor-in-Chief & Co-Founder - Cyber Security News & GBHackers On Security.

Latest articles

Evasive Panda Attacking Cloud Services To Steal Data Using New Toolkit

The Evasive Panda group deployed a new C# framework named CloudScout to target a...

Massive Midnight Blizzard Phishing Attack Using Weaponized RDP Files

Researchers warn of ongoing spear-phishing attacks by Russian threat actor Midnight Blizzard targeting individuals...

Sophisticated Phishing Attack Targeting Ukraine Military Sectors

The Ukrainian Cyber Emergency Response Team discovered a targeted phishing campaign launched by UAC-0215...

Chinese Hackers Attacking Microsoft Customers With Sophisticated Password Spray Attacks

Researchers have identified a network of compromised devices, CovertNetwork-1658, used by Chinese threat actors...

Free Webinar

Protect Websites & APIs from Malware Attack

Malware targeting customer-facing websites and API applications poses significant risks, including compliance violations, defacements, and even blacklisting.

Join us for an insightful webinar featuring Vivek Gopalan, VP of Products at Indusface, as he shares effective strategies for safeguarding websites and APIs against malware.

Discussion points

Scan DOM, internal links, and JavaScript libraries for hidden malware.
Detect website defacements in real time.
Protect your brand by monitoring for potential blacklisting.
Prevent malware from infiltrating your server and cloud infrastructure.

More like this

SYS01 InfoStealer Malware Attacking Meta Business Page To Steal Logins

The ongoing Meta malvertising campaign, active for over a month, employs an evolving strategy...

Russian Hackers Attacking Ukraine Military With Malware Via Telegram

Researchers discovered a Russian-linked threat actor, UNC5812, utilizing a Telegram persona named "Civil Defense....

LightSpy iOS Malware Enhanced with 28 New Destructive Plugins

The LightSpy threat actor exploited publicly available vulnerabilities and jailbreak kits to compromise iOS...