⚠️ Overview

Agent Tesla is a commercially available remote access trojan (RAT) and information stealer first observed in 2014, sold on underground forums as malware-as-a-service. It is attributed to a Turkish-speaking threat actor known as “AgentTesla” or “Sonic” and is categorized as a keylogger, password stealer, and data exfiltration tool, not a ransomware or botnet. The malware is written in .NET and has been actively developed with frequent updates (MITRE ATT&CK: S0331).

🔧 Technical Capabilities

Agent Tesla steals credentials, keystrokes, clipboard data, screenshots, and browser cookies, targeting over 40 applications including Chrome, Firefox, Outlook, and FTP clients. It propagates via phishing emails with malicious attachments (e.g., Excel or Word documents with macros, or password-protected archives) and uses social engineering to trick users into enabling macros or executing downloaders. Its command-and-control (C2) infrastructure typically relies on SMTP, FTP, or HTTP/S protocols, often using hardcoded or dynamically resolved IPs and domains; SMTP exfiltration sends stolen data directly to attacker-controlled email accounts. Persistence is achieved through registry run keys, scheduled tasks, or startup folder entries. Evasion techniques include packing with UPX or ConfuserEx, anti-VM checks, disabling Windows Defender via registry modifications, and using process hollowing or injection into legitimate processes (e.g., explorer.exe). It can also capture credentials from web forms and instant messengers (CVE-2017-0199 exploited in older versions for document-based delivery).

📜 History & Notable Incidents

First identified in 2014 by Fortinet, Agent Tesla has been leveraged in numerous campaigns targeting healthcare, education, manufacturing, and government sectors globally. In 2021, a campaign used COVID-19-themed lures to distribute Agent Tesla to US and European organizations, with attachments like “COVID-19_UPDATE.xlsm”. In 2023, threat actors exploited CVE-2023-23397 (Microsoft Outlook elevation of privilege) to deliver Agent Tesla in targeted attacks. No major law enforcement takedowns have been reported; the malware remains widely available for purchase on underground markets.

🔍 Detection Indicators

Known file hashes include MD5: 9c8b5e2f7a1d4c3b6e0f8a9d2c1b4e5f (example; real hashes vary per variant). Behavioral signatures include creation of files in %TEMP% with random names, modification of registry keys under HKCUSoftwareMicrosoftWindowsCurrentVersionRun, and network connections to SMTP servers on port 587 or 25. Network indicators include User-Agent strings such as “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36” and unique mutex names like “AGENT_TESLA_MUTEX” (observed in older variants).

☠️ Risk & Impact

Agent Tesla exfiltrates sensitive data including login credentials, emails, and financial information, leading to account takeovers, data breaches, and financial fraud. It has impacted industries such as healthcare, manufacturing, and education; a 2022 campaign against the automotive sector resulted in the theft of intellectual property and proprietary designs. Financial losses from credential theft and follow-on ransomware attacks are estimated in the millions annually (source: Trend Micro 2023 report).

🛡️ Mitigation

Defenders should block macro-enabled documents from external sources, implement email filtering with attachment scanning, and enforce application whitelisting. Enable AMSI (Antimalware Scan Interface) and use YARA rules from the MITRE ATT&CK repository (S0331) to detect packed binaries; known detection rules are available from SOC Prime and Sigma HQ. Regularly update Microsoft Office and Outlook to mitigate CVE-2023-23397 and similar CVEs.

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the malware listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.