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TrickBot Campaign Uses Fake Payroll Emails to Conduct Phishing Attacks
TrickBot phishing campaign used SendGrid, fake Google Docs, and Drive-hosted downloaders disguised as Word files to deliver a credential-stealing payload.
Unit 42 identified a TrickBot distribution campaign on November 7-8, 2019, using payroll and annual bonus-themed emails sent from likely compromised .edu addresses through the legitimate SendGrid email delivery service. Emails contained links to Google Docs documents linking to downloader executables hosted on Google Drive, further masked behind SendGrid click-tracking URLs. The downloaders, signed by PERISMOUNT LIMITED and displayed with Microsoft Word icons, show a decoy pop-up and retrieve TrickBot payloads from compromised legitimate domains such as savute[.]in and lindaspryinteriordesign[.]com. The newer TrickBot variant stores its files and configuration under %APPDATA%\cashcore.
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"Blank Slate" Campaign Takes Advantage of Hosting Providers to Spread Ransomware
Unit 42 profiles the Blank Slate malspam campaign: blank emails with double-zipped attachments delivering Cerber ransomware while cycling abused hosting provider domains.
The Blank Slate campaign sends empty emails containing double-zipped archives with macro-enabled Word documents or JavaScript files that launch PowerShell to download ransomware, primarily Cerber, and occasionally Sage 2.0 or Locky. Unit 42 observed 555 campaign domains over seven months, with actors repeatedly registering new domains and cycling abuse of legitimate hosting providers after takedowns. In a five-day January-February 2017 window, at least eight domains across seven IP addresses were observed hosting Cerber payloads.
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xHunt Campaign: New Watering Hole Identified for Credential Harvesting
Unit 42 tied the xHunt campaign to a watering hole on a Kuwait government website used to passively harvest visitors' NTLM credential hashes.
Palo Alto Unit 42 identified a Kuwait government organization's webpage injected with hidden HTML referencing image paths on domains (microsofte-update.com, learn-service.com) tied to xHunt/Hisoka C2 infrastructure. When visitors loaded the page, Windows would attempt SMB/NetBIOS authentication to the remote share, allowing the operators to capture NTLM hashes that could be cracked or relayed. Related DNS redirect activity on xHunt infrastructure in 2019 pointed to additional credential-harvesting interest against Kuwaiti government email servers.
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KRBanker Targets South Korea Through Adware and Exploit Kits
Unit 42 details KRBanker banking trojan targeting South Korean bank users via KaiXin exploit kit and NEWSPOT adware, using pharming and process hollowing.
KRBanker (aka Blackmoon) is a banking trojan targeting online banking users in the Republic of Korea, with roughly 2,000 unique samples and 200+ pharming servers observed by Unit 42 over six months. It is distributed through the KaiXin exploit kit exploiting Adobe Flash CVE-2014-0569 and CVE-2015-3133, and through the NEWSPOT adware update channel that also delivers the Venik trojan. The trojan uses process hollowing, retrieves pharming server IPs from Qzone profile nickname fields, and abuses Proxy Auto-Config with a local proxy to redirect banking traffic to forged sites.
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New Mirai Variant Targeting Network Security Devices
New Mirai botnet variant exploits nine vulnerabilities in SonicWall, D-Link, Netgear, and other devices, with attacks ongoing at publication.
Unit 42 observed attacks exploiting VisualDoor (SonicWall SSL-VPN), CVE-2020-25506 (D-Link DNS-320), CVE-2020-26919 (Netgear ProSAFE Plus), and other flaws, with infrastructure rotating across at least three IP addresses between February 16 and March 13, 2021. Payloads were updated hours after CVE-2021-27561 and CVE-2021-27562 (Yealink Device Management, unauthenticated root RCE) and later added CVE-2021-22502 (Micro Focus Operation Bridge Reporter) and CVE-2019-19356 (Netis WF2419). Successful exploitation invokes wget to fetch shell scripts that download Mirai binaries compiled for multiple architectures and brute-forcers, and attacks were still ongoing when reported.
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Threat Assessment: Ryuk Ransomware
Unit 42 assesses Ryuk ransomware amid a CISA/FBI/HHS alert on threats to U.S. healthcare, including the UHS attack that disrupted hospital operations.
A joint CISA, FBI, and HHS alert on October 28, 2020 warned of an imminent threat to U.S. healthcare from operators deploying Trickbot and Ryuk ransomware. Universal Health Services reported a Ryuk attack that disrupted all U.S. UHS sites for weeks, with similar incidents at hospitals in Oregon and New York. Ryuk typically arrives after Trickbot or BazaLoader infections delivered via malicious email, and operators enumerate networks with PowerShell and WMI before encryption. The Trickbot Anchor_DNS module performs DNS tunneling for C2, using connectivity checks to benign domains like ipinfo.io and checkip.amazonaws.com.
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Threat Brief: Maze Ransomware
Unit 42 issued a threat brief on Maze ransomware, noting an uptick across industries and exploitation of Pulse VPN and IE flaws for initial access.
Palo Alto Networks detected an uptick in Maze ransomware samples across finance, healthcare, government, and other sectors. Maze, a variant of ChaCha ransomware first seen in May 2019, is distributed via weaponized Word/Excel attachments and the Spelevo exploit kit leveraging CVE-2018-15982 and CVE-2018-4878, and has used CVE-2019-11510 (Pulse VPN) and CVE-2018-8174 (Internet Explorer). Operators establish a foothold, escalate privileges, move laterally, and exfiltrate files before encryption for extortion leverage.
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MILE TEA: Cyber Espionage Campaign Targets Asia Pacific Businesses and Government Agencies
Unit 42 names MILE TEA, a cyber-espionage campaign since 2011 targeting Japanese and Taiwanese businesses and government agencies with e-ticket phishing lures and Elirks-family malware.
Unit 42 tracks the MILE TEA espionage campaign, observed as early as 2011, targeting Japanese trading, petroleum, and mobile companies, a Beijing office of a Japanese public organization, and a Taiwanese government agency. The primary infection vector is spear-phishing emails with attachments, mostly custom executable installers posing as flight e-tickets, dropping Elirks, Micrass, or Logedrut as initial bridgehead malware. Elirks and Logedrut retrieve encrypted C2 addresses from attacker-posted blog articles, decoded with Base64 and TEA or DES ciphers. The campaign's focus shifted from Taiwan to Japan around 2013.
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Banking Trojans: Ursnif Global Distribution Networks Identified
Unit 42 maps banking-trojan distribution networks: spam botnets push Shiotob downloaders and Ursnif, KINS, Tinba at Japan and European targets via compromised web servers.
Unit 42 identified the distribution networks behind banking trojan attacks against Japan, Italy, Spain, Poland, Australia, and Germany. A spam botnet delivered 75 unique Shiotob (Bebloh/URLZone) variants across 7 million spam emails, with Shiotob acting mainly as a downloader that installs Ursnif and the Pushdo spam bot from C2 commands. Over 200 malicious files were hosted on 74 compromised, mostly European small-business web servers between April 2015 and January 2017, with localized invoice and photo-themed email lures per target country.
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“Tick” Group Continues Attacks
Unit 42 tracks the Tick espionage group attacking Korean and Japanese defense and high-tech targets with Daserf, Minzen, 9002, Invader, and custom Gh0st RAT variants.
The Tick group has conducted long-running espionage attacks against organizations in the Republic of Korea and Japan, focusing on defense and high-tech companies holding intellectual property, and repeatedly attacked one high-profile Japanese target for three years. Unit 42 links the Daserf backdoor, the 9002 RAT, and the Invader backdoor through shared C2 infrastructure used between July 2012 and April 2013. Minzen samples install a "NamelessHdoor" backdoor derived from publicly available code over a decade old, modified with ReflectiveDLLLoader DLL injection, and the group also uses custom Gh0st RAT variants. Tick has shifted from privacy-protected domain registration to compromised websites for C2 infrastructure.
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