Rtf.Dropper.Agent-9965975-1 — RTF / .DOC malware analysis

Static analysis result for SHA-256 a848f66c8597488a…

MALICIOUS

RTF / .DOC

2.42 MB First seen: 2023-04-24
MD5: 4da4a82bca78fa384d1ffca10c5df5fd SHA-1: f178dbc08cf99092dd281e44af94108e9c922e12 SHA-256: a848f66c8597488ab423ed3da7e094fd2cbf691905af066b23f087365e4fec83
342 Risk Score

Malware Insights

Rtf.Dropper.Agent-9965975-1 · confidence 95%

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

The RTF document contains multiple indicators of exploitation for CVE-2017-11882, including OLE object data and Equation Editor-related heuristics. The presence of PE headers within the hex data suggests that the embedded OLE object is a payload designed to be executed. ClamAV detection as 'Rtf.Dropper.Agent-9965975-1' further supports its function as a dropper.

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.
  • 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.
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
  • \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 ~1543KB 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
  • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00080066.bin
4e5c74ff98c92db58d56f19c95e62b66950d3ebb04c7b45e41b2b9a9c4a28b92		 rtf-objdata-decoded RTF \objdata at offset 0x80066 523392 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.
objdata_01_off0018a6be.bin
7cf2ec81d9b22a062faef0abbae74972826fd90da53e56d6d1b42dff417c7bad		 rtf-objdata-decoded RTF \objdata at offset 0x18A6BE 187184 bytes

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