Office (OLE) / .XLSX malware analysis — malicious · a4ddcef35bbe35d9

MALICIOUS

Office (OLE) / .XLSX

78.0 KB Created: 2023-01-26 17:22:13 Authoring application: Microsoft Excel First seen: 2023-01-29

MD5: 21497dca77b7f76b2b98b1b6dfd2f1e5 SHA-1: f3a41bac9da85d737ee2e71a45e7846f079ab31b SHA-256: a4ddcef35bbe35d9283781a4e0014f4a576fdaeae4a3c1bc4c9bb956f6b5b8b3

328 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

The file contains VBA macros, specifically a Workbook_Open event, which is designed to execute automatically when the workbook is opened. The macro references ShellExecuteA and URLDownloadToFile APIs, indicating an intent to download and execute a payload from a remote source. The ClamAV detection name 'Xls.Malware.Valyria-10033383-0' further supports its malicious nature.

Heuristics 8

Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD

Reference to URLDownloadToFile API
URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD

URLDownloadToFile in VBA
ClamAV: Xls.Malware.Valyria-10033383-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Malware.Valyria-10033383-0
Reference to ShellExecute API high SC_STR_SHELLEXEC

Reference to ShellExecute API
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
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 macros detected medium OLE_VBA_MACROS

Document contains VBA macro code
Environ() call (env variable access) low OLE_VBA_ENVIRON

Environ() call (env variable access)

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `a187c5f5443d78739de3c863391a021cc9c3c5bb6960eb58fc750b53497cfdad`	vba-macro	oletools.olevba.extract_macros (decoded VBA source)	17981 bytes

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