Office (OOXML) / .XLSM malware analysis — malicious · 3f74f790d403f905

MALICIOUS

Office (OOXML) / .XLSM

435.4 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: 61e24518ec3a1928f9673252525617dd SHA-1: ff631d8250dea5ae0e3b377ce4e4cab5e5ea7f70 SHA-256: 3f74f790d403f905b1a8193f367e8d13c52b2a5bd41d993f0f47f19cbf529fc4

148 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell

The sample is an XLSM file containing VBA macros. The Workbook_Open macro is triggered upon opening the document. It reconstructs a command string by concatenating environment variables and other values, then executes it using CreateObject. The reconstructed command appears to be a path to a file named 'update.exe' in a public documents directory, suggesting the macro's intent is to download and execute a second-stage payload. The VBA code uses Environ() and CreateObject, aligning with T1059.005 and T1059.003.

Heuristics 5

Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
CreateObject call high OLE_VBA_CREATEOBJ

CreateObject call
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 project inside OOXML medium OOXML_VBA

Document contains vbaProject.bin — VBA macros present
Environ() call (env variable access) low OLE_VBA_ENVIRON

Environ() call (env variable access)

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `0ae976a8d37e840e426b072af124c76b767899a6ad5700b4a118dddf1f089252`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	1177 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `32107b3de1e6522f06916ead9a94942bc1b019d38827aa7d704c71c54b411f79`	vba-project	OOXML VBA project: xl/vbaProject.bin	9216 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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