Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 fda413c75736cbef…

MALICIOUS

RTF / .DOC

1.60 MB First seen: 2022-05-09
MD5: 376ee2cd76269d4746d440b2b0263f5b SHA-1: 9b863b0db1d4e64948b045363f60bab13f0c65e1 SHA-256: fda413c75736cbef772903782bf93d919cb4857a6f394458bb1fbf4e273612fd
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability through a crafted Equation Editor object. This exploit is designed to execute arbitrary code. The embedded script, although truncated, appears to be a Visual Basic script that attempts to download and execute a second-stage payload, as indicated by the presence of strings like 'Client.vbs' and references to network activity. The script's intent is to facilitate further malicious actions on the compromised system.

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.

FilenameKindSourceSize
objdata_00_off00001291.bin
3c57e2b822119033644773dc57e64b6b9e7afb4c6539fe0694981b99ec9b73b3		 rtf-objdata-decoded RTF \objdata at offset 0x1291 86800 bytes
objdata_01_off00037206.bin
c6836530895d3068b0bd13b6673e20cfb3c2472da47cd4c3fb2419898144731b		 rtf-objdata-decoded RTF \objdata at offset 0x37206 345132 bytes

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