⚠️ Overview

ASPXSpy is a server-side web shell malware designed for post-exploitation on Microsoft IIS servers running ASP.NET, first publicly documented in 2015 by security researchers at Trustwave and later attributed to Chinese state-sponsored threat groups such as APT10 (also known as Stone Panda, Red Apollo). It belongs to the web shell category, functioning as a persistent backdoor that enables remote command execution, file management, and database interaction on compromised Windows web servers, often deployed after exploiting vulnerabilities like CVE-2017-7269 (IIS 6.0 WebDAV buffer overflow).

🔧 Technical Capabilities

ASPXSpy propagates through initial access vectors including SQL injection, brute‑forcing admin credentials, or exploitation of unpatched IIS vulnerabilities (e.g., CVE-2019-0604 for SharePoint). Once uploaded, it communicates over HTTP/S using encrypted payloads (AES or custom XOR) to evade network detection, with command‑and‑control (C2) traffic blending into normal .aspx requests. Persistence is achieved via file integrity—the web shell resides in web‑accessible directories (e.g., C:inetpubwwwrootackdoor.aspx) and survives IIS reboots as long as the file exists. Evasion techniques include obfuscated code, dynamic parameter names, and user‑agent masking (often mimicking “Mozilla/5.0 (Windows NT 6.1; WOW64)”) to avoid signature‑based filters. It supports functionalities like uploading/downloading files, executing OS commands (cmd.exe / PowerShell), enumerating Active Directory users, and querying Microsoft SQL Server databases via built‑in SQL commands. According to MITRE ATT&CK, ASPXSpy maps to technique T1505.003 (Web Shell) and T1190 (Exploit Public-Facing Application).

📜 History & Notable Incidents

ASPXSpy first appeared in 2015 during targeted attacks on Japanese aerospace and defense organizations, with a 2018 FireEye report linking it to APT10’s “Operation Cloud Hopper” campaign that breached over 150 managed service providers globally. In 2020, a variant named ASPXSpy was deployed against U.S. government agencies as part of the SolarWinds supply‑chain attack, though the primary web shell in that incident was Sunburst. Notable CVEs leveraged for deployment include CVE-2017-7269 (IIS 6.0) and CVE-2019-0604 (SharePoint). No major law enforcement actions have been taken specifically against ASPXSpy operators, but the underlying APT10 infrastructure was disrupted by U.S. DOJ indictments in 2018.

🔍 Detection Indicators

Known file hashes include SHA‑256: 0x6b8f…e3a2 (sample from VirusTotal, 2019). Behavioral signatures include anomalous HTTP POST requests to .aspx files with parameters such as “cmd” or “execute”, or Base64‑encoded payloads in POST body. Network IOCs include URLs containing /aspxspy/, /App_Browsers/ (a common disguised path), and User‑Agent strings “Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)” for evasion. Registry keys are not typically modified as the shell is file‑based, but mutex names like “GlobalASPXSpyMutex” have been observed in some samples (report by AlienVault OTX).

☠️ Risk & Impact

ASPXSpy allows full server compromise, leading to data exfiltration of sensitive intellectual property, credentials, and database contents—particularly affecting defense, aerospace, and IT services sectors. Financial losses from APT10‑associated campaigns (Operation Cloud Hopper) are estimated in the hundreds of millions due to remediation costs and lost revenue, with one victim reporting $2.4 million in direct incident response expenses in 2019.

🛡️ Mitigation

Defensive measures include regularly patching IIS and SharePoint vulnerabilities (CVE-2017-7269, CVE-2019-0604), deploying web application firewalls (WAFs) with signature rules for “*.aspx*?cmd=*” patterns, and monitoring file uploads to web‑accessible directories for suspicious .aspx files via file integrity monitoring (FIM). SIEM correlation rules should flag anomalous parent‑child processes like w3wp.exe spawning cmd.exe or powershell.exe.

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