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BOOSTWRITE is a Windows malware loader associated with the FIN7 cybercriminal group and linked to delivery of the Carbanak backdoor. It is notable for abusing DLL side-loading and dynamic module loading to execute malicious code through legitimate components. Reported samples were digitally signed with a valid certificate, a tactic consistent with defense evasion and efforts to appear trustworthy.
A characteristic BOOSTWRITE execution chain abuses loading behavior around DWrite-related libraries to cause a malicious local library to be loaded through legitimate dependencies. It also uses the DWriteCreateFactory function to load additional modules, reflecting a modular loader design. Internally, BOOSTWRITE has been observed decoding embedded data with a 32-byte multi-XOR key before loading subsequent components.
BOOSTWRITE has been described as part of FIN7 tooling from 2019 and shares tradecraft and code relationships with other FIN7 loaders. Related investigations found samples with a common codebase carrying the Carbanak backdoor, reinforcing its role as a staging mechanism rather than the final payload. The malware targets Windows systems and is primarily relevant to financially motivated intrusion activity historically associated with FIN7, including operations against sectors such as retail, hospitality, and restaurants, while FIN7 has also expanded into broader enterprise targeting.
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1 distinct threat actor attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.
8 distinct techniques documented for this family, organized by ATT&CK tactic.
Astaroth uses the LoadLibraryExW() function to load additional modules. Attor's dispatcher can execute additional plugins by loading the respective DLLs. ... LightSpy's main executable and module .dylib binaries are loaded using ... dlopen() ... dlsym() ... RotaJakiro uses ... .so files ... using dlopen() and dlsym().
...uses the LoadLibraryExW() function to load additional modules... execute additional plugins by loading the respective DLLs... loaded and executed DLLs in memory during runtime... loads a dynamic library (.dylib file) using dlopen() and obtains a function pointer... using dlopen() and dlsym()... calls LoadLibrary then executes exports from a DLL.
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.
Examples throughout the content include 'encrypted payloads decrypted and executed in memory,' 'encrypts its configuration file,' 'AES-encrypted resource,' 'RC4 encrypted embedded scripts,' and 'payload includes an encrypted main component.'
APT28 macro uses the command certutil -decode to decode contents of a .txt file storing the base64 encoded payload.
...uses the LoadLibraryExW() function to load additional modules... execute additional plugins by loading the respective DLLs... loaded and executed DLLs in memory during runtime... loads a dynamic library (.dylib file) using dlopen() and obtains a function pointer... using dlopen() and dlsym()... calls LoadLibrary then executes exports from a DLL.
The content repeatedly describes threat actors and malware using valid, stolen, forged, self-signed, or abused code-signing certificates to sign malware and appear legitimate, including examples such as AppleJeus using a valid digital signature from Sectigo, APT41 leveraging code-signing certificates, FIN7 signing Carbanak payloads, and SUNBURST being digitally signed by SolarWinds.
2 indicators attributed across vendor reports, sandbox runs, and researcher write-ups. Full values are available in Mallory.
File hashes (MD5, SHA-1, SHA-256) from samples and reports.
10 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Malware that uses a 32-byte multi-XOR key to decode payload data.
Malware that decodes payload data using a 32-byte multi-XOR key.
A FIN7 loader/tool with a shared codebase to BIOLOAD. The content says it targets 32-bit machines, supports multiple payloads, uses ChaCha-based decryption, and can fetch a key from a remote server.
BOOSTWRITE was signed by a valid certificate authority to appear legitimate.
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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.