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

Static analysis result for SHA-256 54bd4d38f3a15017…

MALICIOUS

Office (OLE) / .XLSX

379.2 KB
MD5: 154572bc1a3a7b1f732219dfce1d7985 SHA-1: c79ee1ba99792a20a85dd1b55ce813567d33109a SHA-256: 54bd4d38f3a15017ed0ceab138e8348d3ba97a6789920b50b5e93b5d0eec1ec9
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an encrypted Excel spreadsheet, a common delivery mechanism for malicious documents. The presence of an Equation Editor OLE object, combined with heuristics indicating an exploit carrier and CFB FAT corruption, strongly suggests the exploitation of a known vulnerability within Equation Editor. This is a common technique for initial access, often delivered via spearphishing attachments.

Heuristics 5

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Default-encrypted OOXML embedded OLE object xl/embeddings/oleObject1.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • Encrypted Office package with CFB FAT corruption critical OLE_ENCRYPTED_AND_MALFORMED
    Encrypted-package shape co-occurs with FAT-chain corruption — the documented combined evasion form.
  • Default-encrypted OOXML exploit carrier layout high OOXML_ENCRYPTED_EXPLOIT_CARRIER_SHAPE
    Default-password encrypted OOXML package contains embedded OLE object parts and additional activation/decoy parts. This layout is common in malicious Excel exploit delivery and requires inspecting the decrypted package.
  • Office document is password-encrypted medium OFFICE_ENCRYPTED_PACKAGE
    OLE container holds MS-OFFCRYPTO encrypted package (Standard Encryption (Office 2007, AES)).
  • Office OOXML encrypted with default VelvetSweatshop password medium OFFICE_DEFAULT_PASSWORD_ENCRYPTED_OOXML
    OLE EncryptedPackage decrypts with Excel's built-in VelvetSweatshop password. Office opens this transparently, and malware uses it to hide OOXML exploit parts from scanners that only inspect the outer OLE container.