Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 de7f8d72b85aab38…

MALICIOUS

RTF / .DOC

2.26 MB
MD5: 61d466b622a14959daa00e8b9cb0935e SHA-1: a5f2feb9a183de04087507bc889359f687e57eab SHA-256: de7f8d72b85aab38b98f4a21172188e1c19b5ea650c1d5a40befbc3b0552ab56
180 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects and specifically triggers the CVE-2017-11882 vulnerability through the Equation Editor. This indicates an attempt to execute arbitrary code upon opening the document. The embedded object data, when decoded, contains obfuscated VBA-like code that appears to check for disk space and then attempts to execute a command. The specific exploit mechanism and the presence of obfuscated code suggest a malicious intent to compromise the 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_off00001202.bin
f462ad3e75a331a93a252fbefbd349fa4bf4365b31445a252be8b37ddea69526		 rtf-objdata-decoded RTF \objdata at offset 0x1202 27473 bytes
objdata_01_off0001d0af.bin
7b044241719dc498d7192da41c089b65b5b58d1276cabad9af124a69d1f89421		 rtf-objdata-decoded RTF \objdata at offset 0x1D0AF 483334 bytes

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