Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 0ca8dc2c091cdfb3…

MALICIOUS

RTF / .DOC

42.8 KB First seen: 2023-02-07
MD5: 4685f215690c381fb8351c23abc3fe74 SHA-1: b4001208f28d615cf812d243db86dd3bd0a207df SHA-256: 0ca8dc2c091cdfb307d9d67268fbff66f248d8e572c158b583d0169bc15494f1
200 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically identified as being related to CVE-2017-11882, exploiting the Equation Editor vulnerability. The document also contains a lure instructing the user to 'Enable editing', a common tactic for macro-based malware delivery. The embedded object is likely designed to download and execute a second-stage payload.

Heuristics 6

  • 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 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000579f.bin
87b5ab199531175921a701ff4d56ee6d25ecdf850cf6032ba51a4b5b6456f885		 rtf-objdata-decoded RTF \objdata at offset 0x579F 2053 bytes

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