RTF / .DOC malware analysis — malicious · 7cd290313972faad

MALICIOUS

RTF / .DOC

1.87 MB First seen: 2022-02-22

MD5: 354ca64d34087ef21429760c19cd3652 SHA-1: 0ce736d3a0e219ece53324d169f4dfe920de87d4 SHA-256: 7cd290313972faad40bccb6485984de8f954702ede0a3c2f9b04a684d181f6ae

220 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.001 PowerShell

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to execute embedded OLE object data. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_RELATED` heuristics strongly indicates exploitation of this known vulnerability. The large amount of hex-encoded data within the OLE object suggests it is used to hide a secondary payload, which is then likely executed by the system.

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.
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.
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~1956KB 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off0000113f.bin` `4afa61ab91e232ced97ef8d14d0b2a4fa471d7e173ee4d918d3c64bb8f3da8cd`	rtf-objdata-decoded	RTF \objdata at offset 0x113F	978314 bytes

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