Office (OLE) / .XLSX malware analysis — malicious · 8a28e59bf65cbc8a

MALICIOUS

Office (OLE) / .XLSX

757.0 KB Created: 2021-07-15 12:50:47 Authoring application: Microsoft Excel

MD5: f31c57fd4b561fc20690e064305fa46b SHA-1: a0f435a6b2defbc50769852d1a0f39d696465539 SHA-256: 8a28e59bf65cbc8aeaf26a2a16acdb8e5bba844e5bf067b7743fecf8f78a4548

320 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1140 Deobfuscate/Decode Files or Information T1547.001 Registry Run Keys / Startup Folder T1204.002 Malicious File T1071.001 Web Protocols

The VBA macros in this Excel file are designed to execute automatically upon opening. The script constructs a base64 encoded string, decodes it into bytes, writes it to a zip file in the user's local appdata directory, and then unpacks it. Finally, it establishes persistence by writing a registry key 'HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy' with the value 'C:\Users\<user>\AppData\Local\Microsoft\Windows\Apps\IAccessible2Proxy2.exe,d1Main', indicating it downloads and executes a second-stage payload. The presence of a password-protected archive lure further supports this malicious intent.

Heuristics 8

Shell() call in VBA critical OLE_VBA_SHELL

Shell() call in VBA
Document_Open macro high OLE_VBA_DOCOPEN

Document_Open macro
Auto_Open macro high OLE_VBA_AUTO

Auto_Open macro
CreateObject call high OLE_VBA_CREATEOBJ

CreateObject call
VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC

Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
Password-protected archive handoff high SE_PASSWORD_ARCHIVE_LURE

Document gives password instructions for an archive or attachment — often used to keep payloads encrypted until after gateway scanning
Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
VBA macros detected medium OLE_VBA_MACROS

Document contains VBA macro code

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `3a179b9880c8ee003dc019182dbc4c47d1d51c9fc848e57c1e27d27e6bf95d8e`	vba-macro	oletools.olevba.extract_macros (decoded VBA source)	360772 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.

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