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H1N1 is a Windows malware family that began as a loader used to deliver other malware, including Pony and Vawtrak, and later evolved into an information-stealing threat. It has been distributed in spearphishing campaigns using malicious Microsoft Word documents with heavily obfuscated VBA macros. These documents socially engineer users into enabling macros, then decode and execute an embedded payload through staged de-obfuscation and unpacking routines.
On execution, H1N1 uses multiple unpacking stages and process injection techniques, including creating suspended processes, writing payloads into memory, and injecting into Explorer.exe using a process-replacement approach associated with Duqu-style tradecraft. It employs custom packing and string obfuscation, dynamic import resolution through hashing, and RC4-encrypted command-and-control traffic.
H1N1 has credential-theft functionality, including dumping usernames and passwords from Firefox, Internet Explorer, and Outlook. It also includes privilege-escalation capability through a DLL hijacking-based User Account Control bypass involving the Windows Update Standalone Installer. Defense-evasion behavior includes killing or disabling Windows Security Center and Windows Defender services. Some variants have also been reported to disable recovery options and delete shadow copies, and analysis of later variants identified self-propagation or lateral movement capability. H1N1 is therefore best characterized as a modular Windows infostealer that retains loader heritage and post-compromise functionality.
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24 distinct techniques documented for this family, organized by ATT&CK tactic.
The content repeatedly describes threat actors and malware using cmd.exe, the Windows command shell, to execute commands, launch payloads, run batch files, and automate actions on compromised hosts.
The de-obfuscated executable is then written to %temp% and executed. | we have observed a widely distributed campaign using VBA macros to infect machines with a variant of information-stealing malware.
Use UnMapViewOfSection with ImageBaseAddress and process handle of Explorer.exe from step 2 to un-map the current section
The binary has a total of three routines responsible for unpacking and injection.
CreateProcessW is called to create a suspended ‘Explorer.exe’ process ... UnMapViewOfSection ... Overwrite image sections of Explorer.exe with unpacked executable code ... Call ResumeThread to start execution
Key findings from our analysis include: ... A novel DLL hijacking vulnerability resulting in a User Account Control bypass
The content repeatedly describes malware and threat actors that 'bypass UAC,' 'perform UAC bypass,' or use specific Windows components such as fodhelper.exe, eventvwr.exe, sdclt.exe, CMSTPLUA COM interface, SilentCleanup, and registry hijacks to gain elevated privileges.
The VBA macro is highly obfuscated, making use of many VBA tricks to hide its true intent.
"Sandworm Team used UPX to pack a copy of Mimikatz"; "APT38 has used several code packing methods such as Themida, Enigma, VMProtect, and Obsidium"; "Lazarus Group packed malicious .db files with Themida to evade detection."
"imports are resolved dynamically using hashing of DLLs and exports" / "export names... hashed by walking the export table and performing a simple XOR and ROL loop"
The binary has a total of three routines responsible for unpacking and injection.
CreateProcessW is called to create a suspended ‘Explorer.exe’ process ... UnMapViewOfSection ... Overwrite image sections of Explorer.exe with unpacked executable code ... Call ResumeThread to start execution
The core de-obfuscation functionality is a two steps process. The first is an XOR loop with a fixed byte key of 0xE, which produces a base64 encoded portable executable (PE). The second is a VBA implementation of base64 that decodes it to produce a final Portable Executable (PE).
Agent Tesla can gather credentials from a number of browsers... APT33 has used a variety of publicly available tools like LaZagne to gather credentials... TrickBot can obtain passwords stored in files from web browsers such as Chrome, Firefox, Internet Explorer, and Microsoft Edge... SELECT action_url, username_value, password_value FROM logins; CryptUnprotectData
Agent Tesla can gather credentials from a number of browsers... APT3 has used tools to dump passwords from browsers... APT41 used BrowserGhost, a tool designed to obtain credentials from browsers, to retrieve information from password stores... TrickBot can obtain passwords stored in files from web browsers such as Chrome, Firefox, Internet Explorer, and Microsoft Edge
The content repeatedly describes malware and threat actors that can "download files from C2," "download additional payloads," "upload and download files," "retrieve payloads from the C2 server," and "copy files to remote machines."
The content is a catalog of malware and threat groups that encrypt command-and-control communications using algorithms such as DES, AES, RC4, XOR, Blowfish, RSA, Camellia, RC2, RC6, and custom ciphers.
"3PARA RAT command and control commands are encrypted within the HTTP C2 channel using the DES algorithm in CBC mode..."; "APT33 has used AES for encryption of command and control traffic."; "Carbanak encrypts the message body of HTTP traffic with RC2 (in CBC mode)."; "Duqu ... data stream can be encrypted with AES-CBC."; "PoisonIvy uses the Camellia cipher to encrypt communications."
Examples include Babuk 'can stop anti-virus services', BOLDMOVE disabling daemons, Conficker terminating services, Lazarus malware disabling Windows services, and SolarWinds Compromise where APT29 'used the service control manager on a remote system to disable services associated with security monitoring products.'
Akira will delete system volume shadow copies via PowerShell commands. Avaddon deletes backups and shadow copies using native system tools. Babuk has the ability to delete shadow volumes using vssadmin.exe delete shadows /all /quiet. BlackCat can delete shadow copies using vssadmin.exe delete shadows /all /quiet and wmic.exe Shadowcopy Delete; it can also modify the boot loader using bcdedit /set {default} recoveryenabled No.
The content repeatedly describes threat actors and malware disabling, stopping, uninstalling, or modifying antivirus, EDR, Windows Defender, AMSI, logging, and other security controls.
Examples include 'Aquatic Panda has attempted to stop endpoint detection and response (EDR) tools', 'BlackByte disabled security tools such as Windows Defender', 'Scattered Spider has uninstalled and disabled security tools', and many malware families terminating AV/EDR processes or services.
1 indicator attributed across vendor reports, sandbox runs, and researcher write-ups. Full values are available in Mallory.
Other indicator types observed in public reporting.
30 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Ransomware that disables recovery options and deletes shadow copies.
Malware that dumps usernames and passwords from browsers and Outlook.
Backdoor that encrypts C2 traffic with RC4.
Mentioned only as a prior example where the same analysis technique was used.
Match every observed IP, domain, and hash against your live telemetry.
Named campaigns wielding this family, with evidence pinned to each claim.
CVEs this family uses for access and lateral movement.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Every documented technique, ranked by evidence weight.
Reddit, Mastodon, and CTI community discussion around this family.