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Chrommme is a Windows backdoor associated with the Gelsemium cyberespionage ecosystem. It has been observed alongside other Gelsemium tooling and shares operational overlap with that cluster, which has targeted organizations in East Asia and the Middle East, including government, religious, education, and electronics-sector entities.
Chrommme supports host reconnaissance and collection functions including retrieving the current username, enumerating the compromised host’s IP address, collecting local system information, and capturing screenshots. It can stage collected information locally prior to theft, including encrypting data and storing it on disk before transmission. Exfiltration is performed over its command-and-control channel. Reported execution behavior includes use of Windows API functionality such as WinExec.
The available evidence supports classifying Chrommme as a backdoor used for espionage-oriented post-compromise activity, particularly host profiling, collection, local staging, and command-and-control-based exfiltration on Windows systems.
Mallory pivots from this family to the IOCs, detections, and named campaigns that touch your stack, and pages you when something new lands.
1 distinct threat actor attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.
Chrommme: Chrommme is a backdoor we found during our adventures in the Gelsemium ecosystem.
18 distinct techniques documented for this family, organized by ATT&CK tactic.
The content repeatedly describes payloads, strings, configuration files, scripts, URLs, and binaries being obfuscated or encoded using Base64, XOR, RC4, AES, RSA, hex encoding, custom algorithms, and other methods across many malware families and threat actors.
AdFind can extract subnet information from Active Directory; actors used ipconfig /all after exploiting a machine; numerous malware and groups used ipconfig, ifconfig, arp, route, netsh, nbtstat, NBTscan, and related APIs to gather IP, MAC, DNS, DHCP, gateway, proxy, domain, ARP cache, routing, and adapter details.
The content repeatedly describes malware and threat actors collecting the username, identifying the current user, enumerating logged-on users, or running commands such as whoami, query user, and quser to determine user context on compromised systems.
The content repeatedly describes malware and threat actors collecting host details such as hostname, OS version, architecture, CPU, memory, BIOS, language, and other machine characteristics; e.g., "Action RAT has the ability to collect the hostname, OS version, and OS architecture of an infected host."
Multiple entries describe enumerating local, logical, or physical drives and disk/volume information, e.g., 'can enumerate local drives,' 'GetLogicalDrives,' 'fsutil fsinfo drives,' 'list drives,' and 'discover logical drive information including the drive type, free space, and volume information.'
The content repeatedly describes threat actors and malware collecting, stealing, identifying, copying, or staging files, documents, credentials, logs, databases, and other information from compromised hosts or local systems.
The content repeatedly describes adversaries and malware storing collected data, command output, credentials, archives, or files in local temporary folders, working directories, hidden directories, registry locations, recycle bins, or specific files prior to exfiltration.
"Agent Tesla can capture screenshots of the victim’s desktop"; "AppleSeed can take screenshots on a compromised host"; "APT28 has used tools to take screenshots from victims"; "Cobalt Strike's Beacon payload is capable of capturing screenshots"; "PowerSploit's Get-TimedScreenshot Exfiltration module can take screenshots at regular intervals"; "Hydraq includes a component based on the code of VNC that can stream a live feed of the desktop"
"AppleSeed has compressed collected data before exfiltration."; "APT28 used a publicly available tool to gather and compress multiple documents..."; "Aria-body has used ZIP to compress data..."; "Cadelspy...compress stolen data into a .cab file."; "Daserf hides collected data in password-protected .rar archives."; "FIN6 has compressed log files into a ZIP archive prior to staging and exfiltration."; "Lazarus Group has compressed exfiltrated data with RAR...archive specified directories in .zip format"; "XCSSET will compress entire ~/Desktop folders..."
ADVSTORESHELL exfiltrates data over the same channel used for C2... Agrius exfiltrated staged data using tools such as Putty and WinSCP, communicating with command and control servers... numerous malware and groups sent victim data, files, credentials, or host information over existing C2 channels.
16 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Malware that can retrieve the username from a targeted system.
Enumerates the IP address of compromised hosts.
Backdoor found in the broader Gelsemium ecosystem. Although code similarities are limited, shared C&C infrastructure and victim overlap suggest some relationship to the group.
Malware that exfiltrates collected data via its C2 channel.
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.