Rewterz Threat Advisory – Cobalt Bank Robbers Use New ThreadKit Malicious Doc Builder

SEVERITY: Medium

CATEGORY: Vulnerability

PUBLISH DATE: December 14, 2018

ANALYSIS SUMMARY

The Cobalt hacking group has resurfaced with a new variant of the ThreadKit exploit builder kit for Microsoft Office documents. The ThreadKit macro delivery tool with its modified technique deploys a payload on victim’s system called CobInt, a signature malware for the Cobalt group. CobInt, also known as COOLPANTS, is a backdoor used by Cobalt for reconnaissance purposes that was discovered on a command and control (C2) server operated by the hackers.

The group uses advanced phishing techniques in their emails to lure users into downloading the payloads on their system. The email addresses have a domain belonging to financial sector and banks. A remote code is executed by exploiting the following vulnerability in Internet Explorer. The group exploits CVE-2018-8174, a remote code execution vulnerability that exists in the way that the VBScript engine handles objects in memory. This may cause memory corruption and will lead to code execution in the context of current user. If the user is logged in as an administrator, attackers can also gain system access.

IMPACT

Remote Code Execution System Access

Affected Vendors

Microsoft

Affected Products

Internet Explorer

Indicators of Compromise

URLs

hxxp://visa-fraud-monitoring[.]com/t[.]dll

hxxps://webmail[.]microsoft[.]org[.]kz/portal/readme[.]txt

hxxps://webmail[.]microsoft[.]org[.]kz/portal/ajax[.]php

hxxp://servicecentrum[.]info/test[.]xml compass[.]plus

eucentalbank[.]com

europecentalbank[.]com

unibank[.]credit

hxxps://5[.]135[.]237[.]216[/]RLxF

hxxps://86[.]106[.]131[.]207[/]ZxT6

hxxps://86[.]106[.]131[.]207[/]MZB

Malware Hash

(MD5/SHA1/SH256)

dcad7f5135ffa5e98067b46feec2563be8c67934eb3b14ef1aad8ff7fe0892c5 dab05e284a9cbc89d263798bae40c9633ff501e19568c2ca21ada58e90d66891 2b4760b5bbe982a7e26af4ee618f8f2dcc67dfe0211f852bf549db457acd262c e9ab3195f3a974861aa1135862f6c24df1d7f5820e8c2ac6e61a1a5096457fc3 0dedb345d90dbba7e83b2d618c93d701ed9e9037aa3b7c7c58b62e53dab7d2ce eb4325ef1cbfba85b35eec3204e7f79e4703bb706d5431a914b13288dcf1d598 a0292cc74ef005b2e5e0889d1fc1711f07688b93b16ebc3174895d7752a16a23 94155a2940a1d49a92a602a5232f156eeb1d35018847edb9c6002cefe4c49f94 ccb1fa5cdbc402b912b01a1838c1f13e95e9392b3ab6cc5f28277c012b0759f9 69e55d2e3207e29d9efc806ff36f13cd49fb92f7c12f0145f867674b559734a3 0f5c5d07ed0508875330a0cb89ba3f88c58f92d5b1536d20190df1e00ebd3d91 9d9d1c246ba83a646dd9537d665344d6a611e7a279dcfe288a377840c31fe89c e78e800bc259a46d51a866581dcdc7ad2d05da1fa38841a5ba534a43a8393ce9

Remediation

Strictly monitor the given Indicators of Compromise and block where possible. Due diligence is suggested prior to blocking of domains.

If you think you’re a victim of a cyber-attack, immediately send an email to soc@rewterz.com.