Malicious RTF — malware analysis report

Static analysis result for SHA-256 71c94bb0944eb59c…

MALICIOUS

RTF

467.0 KB Created: 2013-08-28 14:12:00 First seen: 2018-11-20
MD5: 90f4ca70fddcde6e77eb4f64e19b5146 SHA-1: 04fde11ea1b694945f8c1203ef5ef0bf69c9ae88 SHA-256: 71c94bb0944eb59cb79726b20177fb2cd84bf9b4d33b0efbe9aed58bb2b43e9c
284 Risk Score

Malware Insights

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

The file is an RTF document containing embedded OLE objects, specifically triggering the Equation Editor vulnerability (CVE-2017-11882). This vulnerability allows for the execution of arbitrary code when the document is opened, likely leading to the download and execution of a secondary payload. The ClamAV detection further confirms the malicious nature of the exploit.

Heuristics 9

  • 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.
  • 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.
  • 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_off00014d21.bin rtf-objdata-decoded RTF \objdata at offset 0x14D21 186608 bytes
SHA-256: 301e028e9bda5fbc7b88f6d9cf0e6078bd934b6182d095da0f3fbe1ccc04194f
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.
objdata_01_off0006ff37.bin rtf-objdata-decoded RTF \objdata at offset 0x6FF37 9782 bytes
SHA-256: 7ba7465859c75f617584ec1f19332ec94c7c505d78a18bd4838e166d5af100af
objdata_02_off0006ff49.bin rtf-objdata-decoded RTF \objdata at offset 0x6FF49 35 bytes
SHA-256: 1188b98b21f50564ab8b476f25b6deab999a2f58a56c4dd0daa0f5883cfa941d

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