Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 5a12f42c23e4b798…

MALICIOUS

RTF / .DOC

4.0 KB First seen: 2022-08-23
MD5: 4f9dba4a9566f5abd0151699aa210d0e SHA-1: 7ab6825606b28b9fb52be3af19d85f8d31848423 SHA-256: 5a12f42c23e4b7984fb92b17f27734c25768119fe1936b86338d0f262aa72768
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains OLE object data, specifically triggering heuristics related to Equation Editor and CVE-2017-11882. The presence of `eQUATION.3` as a ProgID strongly indicates the exploitation of this known vulnerability. This technique is commonly used to deliver a second-stage payload.

Heuristics 5

  • 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.
  • 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.
  • 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 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000007d.bin
28f10159c95061a1b111959a3a092742681d84aa8a92b806da6fa9e0bf03eb90
rtf-objdata-decoded RTF \objdata at offset 0x7D 1721 bytes