Xls.Downloader.94c25b356b5a6cac-9978798-0 — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 62c654b6f0d666be…

MALICIOUS

Office (OLE) / .XLSX

135.0 KB First seen: 2022-10-11
MD5: 87daa4a8fb8b7ad768ca4234e2dca5b6 SHA-1: 8e85f7141166e3a879e02b473bae6d744d0f9e6d SHA-256: 62c654b6f0d666beeb865fb2c3f2c59a2d541be6ad20abdb59cdc9bd10234d1e
280 Risk Score

Malware Insights

Xls.Downloader.94c25b356b5a6cac-9978798-0 · confidence 95%

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious File T1566 Phishing T1566.001 Spearphishing Attachment T1059 Command and Scripting Interpreter

The file is an encrypted Excel spreadsheet containing an Equation Editor OLE object. Heuristics indicate this object is malformed and exploits CVE-2018-0798, a vulnerability in Equation Editor. This suggests the document is a carrier for an exploit that likely downloads and executes a secondary payload.

Heuristics 7

  • 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.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Default-encrypted OOXML contains embedded Equation Editor data with anomalous native stream bytes consistent with a CVE-2018-0798-style exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like.
  • 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.
  • ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.94c25b356b5a6cac-9978798-0
  • 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.