RTF / .DOC malware analysis — malicious · ac60446ee62a4c63

MALICIOUS

RTF / .DOC

854.6 KB First seen: 2023-01-16

MD5: 8c3b40776120bb6020781051b18b1f76 SHA-1: 42ec8c1d7e21ab08c3e26c6aacc80a5d30eb6041 SHA-256: ac60446ee62a4c63ad2fbe1bf3cb41b588a6f34ac33c33c4febb6e504c52d877

180 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1566 Phishing T1204.002 Malicious File

The RTF document contains an embedded OLE object specifically identified as Equation Editor, triggering heuristics related to CVE-2017-11882. This exploit is known to be used for arbitrary code execution. The embedded object is updated via \objupdate, forcing activation and likely leading to the execution of a second-stage payload. No specific malware family was identified, but the exploit vector is clear.

Heuristics 5

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.
\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.
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

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000012be.bin` `bed5ab8d1934764399db0812c3c68f4a1d426b11a78b73f6fd69bffae03aee06`	rtf-objdata-decoded	RTF \objdata at offset 0x12BE	78453 bytes
`objdata_01_off0002d95e.bin` `275989a855ed573de58bb17016afb8dbd79952af0073c34a3ce49b1d7275cf1a`	rtf-objdata-decoded	RTF \objdata at offset 0x2D95E	140544 bytes

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