Malicious RTF — malware analysis report

Static analysis result for SHA-256 24adb369ae81a53f…

MALICIOUS

RTF

1.32 MB Created: 2021-07-14 23:49:00
MD5: edf6d105ebde3c721deaac6ece1f6ec0 SHA-1: ae50c599bb1aedf30d7b59e348537a01f18bb206 SHA-256: 24adb369ae81a53fb86bd3ea86e39f0008ba4ce7e9d79b8db38775e68c17d5d2
342 Risk Score

Malware Insights

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

The RTF file contains multiple indicators of the CVE-2017-11882 exploit, including specific RTF object data, OLE object embeddings, and Equation Editor class IDs. The presence of ".objupdate" further suggests an attempt to force OLE activation, which is a common method for triggering this vulnerability. The excessive hex data within the OLE object likely conceals the exploit payload.

Heuristics 9

  • 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.
  • Equation Editor CLSID critical 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 object class critical RTF_OBJCLASS_EQUATION
    Object class 'equation.4' references Equation Editor
  • ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
  • \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 ~1328KB of hex-encoded data inside \objdata sections — may hide a payload
  • 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
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_01_off00147cdb.bin
1a3ff27c03bac9ab655a63dfdb43398a46de0515ac0d035feac6821565b87984		 rtf-objdata-decoded RTF \objdata at offset 0x147CDB 3570 bytes

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