Malicious RTF — malware analysis report

Static analysis result for SHA-256 c580d77722d85238…

MALICIOUS

RTF

1018.4 KB Created: 2018-04-23 01:01:00 First seen: 2019-11-20
MD5: 30528dc0c1e123dff51f40301cc03204 SHA-1: 398fb04ce9b2e30bce932590e0b86b594c8a97ea SHA-256: c580d77722d85238ed76689a17b0205b4d980c010bef9616b8611ffba21b142e
282 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of exploitation targeting Microsoft Equation Editor, specifically related to CVE-2017-11882. The presence of OLE objects, excessive hex data within objdata sections, and ClamAV detection strongly suggest this vulnerability is being leveraged. This technique allows for arbitrary code execution, likely as part of a spearphishing attachment.

Heuristics 8

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • 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.
  • ClamAV: Doc.Exploit.Cve_2017_11882-7570663-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Exploit.Cve_2017_11882-7570663-1
  • \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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1001KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 4 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.microsoft.com/office/word/2003/wordml In RTF body

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00007850.bin rtf-objdata-decoded RTF \objdata at offset 0x7850 495730 bytes
SHA-256: 8303f3d7ae6ddf07a62f9b51da37552cbd944d410a7d1a427f7032a5ec8e50aa
objdata_02_off000f99d2.bin rtf-objdata-decoded RTF \objdata at offset 0xF99D2 9796 bytes
SHA-256: 4e5349089f80016bb1893b8fd7ba283d0bf099b4885156d97927760dfe8a31bf
objdata_03_off000f99e4.bin rtf-objdata-decoded RTF \objdata at offset 0xF99E4 35 bytes
SHA-256: 1188b98b21f50564ab8b476f25b6deab999a2f58a56c4dd0daa0f5883cfa941d

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