Office (OOXML) / .XLSX malware analysis — malicious · 78e776bddf86344f

MALICIOUS

Office (OOXML) / .XLSX

47.3 KB Created: 2020-02-01 18:28:07 UTC Authoring application: Microsoft Excel 12.0000

MD5: 6d44cb088cbe9484a67be9e07ba22750 SHA-1: 86275eedbefc15ac9dc6fa33893bffd7720345b5 SHA-256: 78e776bddf86344f5bfc5bf8edc1abc511631a5cfd629444cd5c86916f4ca23f

380 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1105 Ingress Tool Transfer

The OOXML file contains a VBA macro with an Auto_Open function that utilizes WScript.Shell and CreateObject to execute a Base64-decoded command. This command, reconstructed as http://198.12.66.107/PublicKeyNsFwkrW.exe, indicates the macro's intent to download and execute a second-stage payload from the specified URL. The presence of an Equation Editor OLE object also suggests a potential exploit vector.

Heuristics 9

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/oleObject3.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
Shell() call in VBA critical OLE_VBA_SHELL

Shell() call in VBA
WScript.Shell usage critical OLE_VBA_WSCRIPT

WScript.Shell usage
VBA Base64-decoded Shell command stager critical OLE_VBA_BASE64_SHELL_COMMAND_STAGER

VBA auto-exec macro decodes Base64 string literals into command or script-launch text and executes the result with Shell. This catches cmd/cscript/PowerShell/VBS launchers hidden from plain keyword matching.

URL http://198.12.66.107/PublicKeyNsFwkrW.exe
Auto_Open macro high OLE_VBA_AUTO

Auto_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
Embedded OLE object medium OOXML_OLE_OBJECT

Document contains an embedded OLE object

Extracted artifacts 9

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `2fc3e3f6aec0879bdd32d371b96039b425ad0d8a5303590c9f7fe11e5b9d4525`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	44927 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 1 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.
`ooxml_oleobject_00.bin` `ad42f9bcec245333b066b8e87c61bb3de70ad9ab48c06903fa4454956115c514`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject1.bin	3584 bytes
`ooxml_oleobject_00_ole10native_00.bin` `b3873bb2e38f71b3e635388edfb18d16a315d650487fd6a1fa0f478fa060bac0`	ole-package	OOXML xl/embeddings/oleObject1.bin Ole10Native stream: Ole10Native	1002 bytes
`ooxml_oleobject_01.bin` `ed53cfba4460275d62d43305be97f319b562bda73b2177bdf53c4429219b5393`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject3.bin	5936 bytes
`ooxml_oleobject_02.bin` `c5ebdb5051a3166de28cd42fec7689d007d9b10424da42cecd973f298f83a873`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject2.bin	9216 bytes
`ooxml_oleobject_02_ole10native_00.bin` `8f88b7cf119dc067c70018d4d2dfb6db9a88a99ed2302fecf22588f5e7dcad61`	ole-package	OOXML xl/embeddings/oleObject2.bin Ole10Native stream: Ole10Native	6411 bytes
`ooxml_oleobject_03.bin` `d86d74b6baeea59b3feea0cb92e1573d3bdf3f1e217d03e83e6083827533afb7`	ooxml-ole-object	OOXML embedded OLE part: xl/vbaProject.bin	72704 bytes
`emf_00.emf` `979dde2aed02f077c16ae53546c6df9eed40e8386d6db6fc36aee9f966d2cb82`	ooxml-emf	OOXML EMF part: xl/media/image1.emf	4968 bytes
`emf_01.emf` `4d4d1e7b04c99dcb8e885915068ad6f74cc2333e91580cdae5ccaa00c427247f`	ooxml-emf	OOXML EMF part: xl/media/image2.emf	1536 bytes

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