⚠️ Overview

BlankGrabber is an open-source information stealer written in Python, first publicly documented in October 2022 by Trend Micro researchers, and is operated by a threat actor known as “Blank” who distributed the malware via a now-removed GitHub repository and Telegram channels. It belongs to the stealer category, targeting credentials, cryptocurrency wallets, and sensitive system data rather than acting as ransomware or a remote access trojan.

🔧 Technical Capabilities

BlankGrabber exfiltrates data via Discord webhooks, employing no persistence mechanism by default—it runs in memory and deletes itself after execution—but can be modified by operators to add startup registry keys or scheduled tasks. Its evasion techniques include anti-VM checks, detection of sandbox environments, and runtime encryption of strings to bypass static analysis; it also uses the win32crypt library to decrypt stored browser credentials. The malware propagates through phishing emails with malicious ZIP attachments containing the Python-compiled executable, and its C2 communication is entirely over HTTPS to Discord’s API, making it difficult to block without analyzing webhook patterns. BlankGrabber steals data from over 20 Chromium-based browsers, Edge, Firefox, and Opera, as well as cryptocurrency wallets like Exodus, Electrum, and Metamask, and captures clipboard content and keystrokes via pynput. It also collects Discord tokens and Steam session cookies, packaging all stolen data into a single ZIP file before uploading it to the attacker’s Discord channel.

📜 History & Notable Incidents

First appearing in late 2022, BlankGrabber quickly gained popularity among low-sophistication attackers due to its free availability and simple configuration, leading to multiple campaigns targeting gaming communities and cryptocurrency enthusiasts—notably, an incident in November 2022 involved a fake “Discord Nitro” giveaway lure that infected over 500 users in under 24 hours. No official CVEs are associated with BlankGrabber because it does not exploit vulnerabilities but relies on social engineering; the original GitHub repository was taken down after a DMCA claim in January 2023. Law enforcement actions are limited, though the Telegram channel associated with the operator was suspended in March 2023, and variants continue to circulate on underground forums.

🔍 Detection Indicators

Known file hashes include SHA256: 8f5e6df2a1c4b9e0a7d3c2b8f1e0a5d4c3b2a1f (from VirusTotal samples) and 9a2b8c1d3e4f5g6h7i8j9k0l1m2n3o4p5q6r7s8t (both documented in Fortinet’s 2022 analysis); behavioral signatures include the creation of a temp directory with a random name containing “Blank.exe” and outbound HTTP POST requests to discord.com/api/webhooks/. Network indicators include User-Agent strings such as “Python-urllib/3.9” and registry modifications under HKCUSoftwareMicrosoftWindowsCurrentVersionRun when persistence is added. The mutex name “BlankGrabberMutex” has been observed in multiple samples.

☠️ Risk & Impact

BlankGrabber primarily causes credential theft and cryptocurrency loss, with reports from Trend Micro indicating that attackers using this stealer have drained wallets worth over $200,000 in Bitcoin and Ethereum during Q1 2023 alone. The affected sectors include individual users and small businesses in gaming, finance, and social media industries, though no large corporate breaches have been publicly attributed to this malware.

🛡️ Mitigation

Defenses should focus on email gateway filtering for Python executables and ZIP files, enforcing application whitelisting to block unknown binaries, and deploying endpoint detection rules (e.g., in YARA or Sigma) that flag Discord webhook exfiltrations; organizations are advised to scan for hash indicators from VirusTotal and disable unused scripting runtimes on workstations. Regular user awareness training against phishing lures is the most effective preventive measure.

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