Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 685a21a449aa1414…

MALICIOUS

Office (OOXML) / .XLSX

819.0 KB Created: 2021-08-09 02:12:21 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-06-08
MD5: 5f99db6eeab20b02c272c475f3dcf56b SHA-1: 03553784edaebd2476d3c6fd2f44888f0b429ee4 SHA-256: 685a21a449aa1414d3919570dc0aae7ad2d784685893037dfc4bd60e9cd4b922
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an Excel file containing an embedded Equation Editor OLE object. Heuristics indicate this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798 or a similar vulnerability in Equation Editor to achieve arbitrary code execution. The presence of a NOP sled further supports this. As this is a document, the likely initial access vector is spearphishing attachment.

Heuristics 5

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/dyGF.KvIYu contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Embedded Equation Editor OLE data contains anomalous native stream bytes consistent with a CVE-2018-0798-style Equation Editor exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like, but it does not match the exact public matrix-overflow byte signature.
  • NOP sled detected high SC_NOP_SLED
    Found 20+ consecutive 0x90 bytes
  • Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY
    Embedded OLE object declares the Equation Editor CLSID but stores a large high-entropy Ole10Native stream with malformed package sizing. This is an exploit-shaped Equation/OLE payload container seen in malicious OOXML samples. It is not assigned to a specific CVE unless the MTEF/Equation Native primitive also matches.
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
f97cfb4b6a5f540467c7016088bf438863cea441e3b93d6fda4843f6d6c41f8b		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/dyGF.KvIYu 1120768 bytes
ooxml_oleobject_00_ole10native_00.bin
0dc51c7db6d0df54ca5c4fa26273912f49a436b4b38bb1b6407dd865febb56aa		 ole-package OOXML xl/embeddings/dyGF.KvIYu Ole10Native stream: OLe10NaTIvE 1109397 bytes

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