RTF malware analysis — malicious · 00915bcbff87b2e1

MALICIOUS

RTF

2.78 MB First seen: 2022-08-08

MD5: a5b0c571197ee2931e12f11caf138eff SHA-1: a4355fe45e321b99274f8000c5ac9c08f7146b28 SHA-256: 00915bcbff87b2e195e1547df8e1944cadcdc6aa46beb130bd5a960dff01c7e3

442 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File: User Execution T1559.001 Component Object Model Hijacking

The RTF document contains embedded OLE objects and exploits CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of a PE header within the hex-encoded data and ClamAV detections for 'Rtf.Dropper.Agent-9965975-1' and 'Win.Trojan.AsyncRAT-9914220-0' strongly indicate that this file is a dropper for a malicious payload, likely a trojan.

Heuristics 11

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.
Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED

RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
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
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
\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 ~1959KB 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_off0000129e.bin` `23cb55d09c9af0ea01d3997f81e4403634133ab2292ab815cb6e19af8df312ae`	rtf-objdata-decoded	RTF \objdata at offset 0x129E	985413 bytes
Detection ClamAV: Win.Trojan.AsyncRAT-9914220-0 Obfuscation or payload: likely Carved artifact entropy is 7.64, consistent with packed or encrypted content.
`objdata_01_off001e86a6.bin` `ffd8c2482cc64da211bcb7ca32c7331bf3796ad5ca2159f697062f334496c915`	rtf-objdata-decoded	RTF \objdata at offset 0x1E86A6	187349 bytes

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