RTF / .DOC malware analysis — malicious · 1f2de247ae1b09f1

MALICIOUS

RTF / .DOC

5.49 MB First seen: 2023-02-21

MD5: eeaf5e4b7851b97592dc8ffd34d826c9 SHA-1: c02f276394aed1c50b460b6b22c9fdb7d88e9eff SHA-256: 1f2de247ae1b09f1ded617af4ebe08fbb6b034f80287a871aa3881b2b0014cf3

220 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an RTF document containing a malicious OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The object data is heavily obfuscated and contains a PE executable, indicating it's designed to download and execute a second-stage payload. The presence of extasciitilde{}5.7MB of hex-encoded data within the OLE object further supports the payload hiding mechanism.

Heuristics 5

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.
Decoded Equation Editor payload + PE critical RTF_EQUATION_EDITOR

RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
\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 ~5698KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00000079.bin` `bc0e7f443722099b8c0c99dff5c423ad1ef6ff04e003ca8ad2f82c9488f180bf`	rtf-objdata-decoded	RTF \objdata at offset 0x79	2855656 bytes

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