Malicious RTF — malware analysis report

Static analysis result for SHA-256 46714a1fd1a5ce59…

MALICIOUS

RTF

721.9 KB Created: 2018-08-23 08:28:00 Authoring application: Microsoft Word 11. 0.5604 First seen: 2019-05-31
MD5: 438944220df1b3b7942ce7263150361f SHA-1: 72eb9dd4e522f66eb3374a7d702af514d31d2937 SHA-256: 46714a1fd1a5ce598f761a885857dee8d90b6e7d6f4a303ecaec246a77b58fff
282 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects and specifically triggers heuristics related to Equation Editor vulnerabilities, including CVE-2017-11882 and CVE-2018-0802. The presence of ".objupdate" indicates an attempt to force OLE activation, which is a common method for exploiting these vulnerabilities to achieve code execution. The document body, while in Vietnamese and discussing political study, does not directly contribute to the exploit mechanism but serves as a lure.

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: Rtf.Exploit.CVE_2018_0802-6825822-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2018_0802-6825822-0
  • \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.
  • Package object class high RTF_OBJCLASS_PACKAGE
    OLE Package object — can wrap arbitrary files
  • OLE object data medium RTF_OBJDATA
    RTF contains 3 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000cd13.bin rtf-objdata-decoded RTF \objdata at offset 0xCD13 333552 bytes
SHA-256: 3d4a79ab0b7f8cee9fc0e425b64155e3e2ba6bc63e762b50e3b2bfa6a84b118d
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.
objdata_01_off000afb29.bin rtf-objdata-decoded RTF \objdata at offset 0xAFB29 9774 bytes
SHA-256: 0786ef50b050f00074dd8fb1ca377ba2dda6a415f91743de474720ca17c3094b
objdata_02_off000afb3b.bin rtf-objdata-decoded RTF \objdata at offset 0xAFB3B 9763 bytes
SHA-256: 33221edecfd7fbd2ac0cc4513d3f49b8bbd2a3d534d9a0ea16214c7c7d070b7a

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