Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 bd255ad9335340a8…

MALICIOUS

RTF / .DOC

18.7 KB First seen: 2021-09-25
MD5: 66f16bb17bfff0f6a8e6649ace27bf3c SHA-1: 10c822c1bbefd74ec2a5470df7dfabc493a29aa0 SHA-256: bd255ad9335340a8231daa7144d22f020d7081e233fee1c031f57c1482ef15d4
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, specifically triggering the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics indicates a high likelihood of exploit code execution. The extasciitilde{}objupdate directive further suggests that the embedded object is intended to be activated automatically upon opening the document, leading to arbitrary code execution.

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.
  • \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_off00001fc2.bin rtf-objdata-decoded RTF \objdata at offset 0x1FC2 1754 bytes
SHA-256: 156ffe7ae02bfddca277cdb3af3a974fb8cd495a4870fa1f0e045f842aa388d1

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