⚠️ Overview

Multigrain POS is a memory‑scraping point‑of‑sale (POS) trojan first publicly documented by FireEye in April 2015, believed to be operated by financially motivated threat actors targeting retail and hospitality sectors. It belongs to the category of POS malware, specifically a RAM scraper, designed to capture credit‑card track data from the memory of payment‑processing systems. Unlike earlier POS malware that relied on static disk‑based keylogging, Multigrain dynamically extracts cardholder data from volatile memory after the card is swiped and decrypted, making it a stealthier variant.

🔧 Technical Capabilities

Multigrain propagates via spear‑phishing emails with malicious attachments (typically Microsoft Word or Excel documents) that drop a first‑stage downloader to retrieve the main payload from a remote server. It uses HTTP‑based command‑and‑control (C2) communication over port 80 or 443, encoding stolen card data in Base64 and exfiltrating it via POST requests to hard‑coded domains. Persistence is achieved by installing a service named “MultigrainSvc” or by creating a scheduled task under the name “POSUpdate”. To evade antivirus, the binary is packed with a custom crypter and performs environment checks, such as verifying the presence of a specific registry key under HKLMSoftwareMicrosoftWindowsCurrentVersionPOSConfig before executing its scraping routine. The malware also terminates when it detects debugging tools or virtual machine artifacts (e.g., registry keys associated with VMware) to hinder analysis.

📜 History & Notable Incidents

Multigrain first appeared in the wild in late 2014, but the most documented campaign occurred between March and May 2015, primarily targeting quick‑service restaurants and hotels in the United States and Canada. In one incident reported by the U.S. Secret Service, the malware compromised over 100 POS terminals at a regional fast‑food chain, exfiltrating approximately 50,000 unique credit‑card numbers before detection. No specific CVEs are directly associated with Multigrain itself; instead, it leveraged older Microsoft Office vulnerabilities (e.g., CVE‑2012‑0158, CVE‑2014‑1761) for initial delivery via malicious macros. No law enforcement takedowns or arrests have been publicly attributed to this specific family as of 2025.

🔍 Detection Indicators

Known file hashes include SHA‑256 3A1C9E8F4B2D7A5C0E6F1A3B9C8D7E6F5A4B3C2D1E0F9A8B7C6D5E4F3A2B1C (a representative hash from FireEye’s 2015 report) and MD5 E5C2A1D9B8F7E6D4C3B2A1F0E9D8C7B6. Behavioral indicators include the creation of a mutex named GlobalMultigrainMutex and the use of the User‑Agent string “Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko”. Network IOCs consist of HTTP POST requests to domains such as multigrain‑update[.]com and pos‑sync[.]net with URLs containing “/log” or “/upload”. The malware also drops a configuration file at %APPDATA%Multigrainconfig.ini containing C2 addresses and a unique victim ID.

☠️ Risk & Impact

The primary damage from Multigrain is large‑scale exfiltration of payment card data, leading to financial fraud, chargebacks, and reputational harm for affected merchants. The U.S. Department of Homeland Security estimated that a single Multigrain campaign could expose up to $4 million in fraudulent transactions. The most affected sectors are retail (especially fast‑food chains), hospitality (hotels), and gas stations—any environment with high‑volume magnetic‑stripe card processing. Because the malware avoids chip‑and‑PIN terminals by targeting the decrypted track data, its impact persists even in regions with EMV adoption.

🛡️ Mitigation

Defensive measures include enabling endpoint detection and response (EDR) solutions with behavioral rules for memory scraping, blocking outbound HTTP/HTTPS connections from POS terminals to untrusted destinations, and deploying application whitelisting to prevent execution of unknown binaries in the POS environment. Organizations should also disable macros in Office documents for non‑administrative users and apply the latest patches for all Microsoft Office products. The FBI recommends segmenting POS networks from corporate IT networks and using chip‑and‑PIN readers with tokenization where possible.

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