Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 3bd9174837ea3dc1…

MALICIOUS

RTF / .DOC

74.1 KB First seen: 2022-02-17
MD5: 4c31d8aff10f6bda1042a9528f25f3dc SHA-1: 6467edecb0d0f3f9d6900351191252716733ce2a SHA-256: 3bd9174837ea3dc17cc933e9a7b1bb67446d84b01f4e167c381eaf98d06c2ef4
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF file contains embedded OLE objects and specifically triggers the CVE-2017-11882 vulnerability through the Equation Editor. This indicates an attempt to exploit a known vulnerability for arbitrary code execution. The presence of `EQUATIOn.3` as a ProgID further confirms the exploitation vector.

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.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000c12.bin
0398b56d7a935ec135f152e91b41596889f8385a6612a5a6560805c93c55aa94
rtf-objdata-decoded RTF \objdata at offset 0xC12 24408 bytes