RTF malware analysis — malicious · 3a0b5b12f26a4751

MALICIOUS

RTF

2.81 MB First seen: 2022-08-23

MD5: 2020683c0740feb8c7a41ea70377b7fc SHA-1: 326a0155051677653084e841125984b63b30666a SHA-256: 3a0b5b12f26a4751964e2660ee62d20b192e00a044cd322f6867acfa25e341bc

342 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File Execution: Malicious File T1566.001 Phishing: Spearphishing Attachment

The RTF document contains embedded OLE objects, specifically exploiting the Equation Editor vulnerability (CVE-2017-11882). The presence of hex-encoded PE headers within the OLE object data strongly suggests that the exploit is used to drop and execute a secondary payload. ClamAV detection as Rtf.Dropper.Agent-9965975-1 further confirms its malicious nature 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 ~1981KB 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.

Filename	Kind	Source	Size
`objdata_00_off00001291.bin` `7331b48fda89d2ffd93b3eb8b09cad05829e283a7a48d5e341fb59a78b7d0368`	rtf-objdata-decoded	RTF \objdata at offset 0x1291	996677 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.
`objdata_01_off001ede8c.bin` `0e956ec33c71a31a2677a62fabab59837a9c0539a96de69de768a617f5f5b6d3`	rtf-objdata-decoded	RTF \objdata at offset 0x1EDE8C	187438 bytes

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