Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 f551779365138214…

MALICIOUS

RTF / .DOC

24.6 KB First seen: 2021-09-15
MD5: 563ff02eda1ac2abf958dde09e06263a SHA-1: bd655ae4a1309ac2860e791bc522452c2b904e0e SHA-256: f5517793651382144ee0cdb01495f99bcf551280c9e547eab243c6d3cd6a52b0
160 Risk Score

Malware Insights

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

The RTF document contains embedded OLE objects, specifically targeting the Equation Editor vulnerability. The presence of ".objdata" sections and the "RTF_EQUATION_EDITOR" heuristic strongly indicate an exploit targeting this component. The ".objupdate" directive suggests automatic activation, leading to code execution. This is a common delivery mechanism for malware.

Heuristics 4

  • 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_off00001511.bin
eb82733488386418d7af5b93bfeb9433224ad97c9eba5a89d6eaef3f1e22746c
rtf-objdata-decoded RTF \objdata at offset 0x1511 1936 bytes