Malicious RTF — malware analysis report

Static analysis result for SHA-256 ac67b718b444b9d0…

MALICIOUS

RTF

27.3 KB First seen: 2020-09-07
MD5: b61d0799b122fc459d0bc7bf85625473 SHA-1: 94d897f0b9b2a30ae36402320b9cda175c710bd3 SHA-256: ac67b718b444b9d02598df49293cca5d9f1f9464a28deac8654755aecbe0c6ba
200 Risk Score

Malware Insights

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

The RTF document contains embedded OLE object data and specifically triggers the CVE-2017-11882 vulnerability related to Microsoft Equation Editor. This exploit is designed to execute arbitrary code, indicating the file's primary purpose is likely to act as a dropper for further malicious activity. No specific family could be identified from the available evidence.

Heuristics 5

  • Split hex Equation Editor ProgID + OLE object critical CVE likely 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.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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_off00001c77.bin rtf-objdata-decoded RTF \objdata at offset 0x1C77 1794 bytes
SHA-256: 05e724077e416a70a10fbdfdce3144185667f7b703cf0955538af5d59eff6464

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