Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 93a7d355c44d820d…

MALICIOUS

RTF / .DOC

24.5 KB First seen: 2023-04-21
MD5: 3d033bae86330584f43ef592838c86e6 SHA-1: 0358ff7f67a24711c56af4b1d0eb68b9a99d22e8 SHA-256: 93a7d355c44d820de74d5311a4e76806d13974c9dfcde76f4c93ae0a4d8c8b3e
120 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.001 PowerShell

The sample is an RTF document that contains an embedded OLE object with a split Equation Editor ProgID, indicating exploitation of CVE-2017-11882. The ".objupdate" directive forces the activation of this object, which is designed to download and execute a second-stage payload. No specific malware family was identified, but the technique is commonly used for initial access.

Heuristics 3

  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000019ec.bin
96ca5cb42bf047f17199feae69b19942dc373e293f8c2c4668da2966566448a6
rtf-objdata-decoded RTF \objdata at offset 0x19EC 1859 bytes