RTF / .DOC malware analysis — malicious · b45db441167bf5be

MALICIOUS

RTF / .DOC

2.62 MB First seen: 2022-05-19

MD5: 3d65ba264ebfe78a6ca2b460e61943e8 SHA-1: 1467ae0145b1e5ebb1c04570c7721c8a19dc0179 SHA-256: b45db441167bf5be3313c22b8b9d7ade4abd2464856a42f32e94fcb57dcdf45f

262 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains OLE object data, specifically leveraging the Equation Editor vulnerability (CVE-2017-11882). The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_RELATED` heuristics strongly indicates exploitation of this known vulnerability. The large, high-entropy embedded OLE object (`objdata_00_off0000006c.bin`) likely contains the second-stage payload. The `RTF_OBJAUTLINK` and `RTF_OBJUPDATE` rules suggest that the OLE object is designed to be automatically activated upon opening the document.

Heuristics 7

Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED

RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact 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.
Automatically linked OLE object high RTF_OBJAUTLINK

RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
\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 ~2750KB 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
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off0000006c.bin` `df57e9fac6d3f1ee3e70dc68890569f37cdc8c632c652e456dd314048a1bffe9`	rtf-objdata-decoded	RTF \objdata at offset 0x6C	1375368 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.

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