Malicious RTF — malware analysis report

Static analysis result for SHA-256 c2728fd832f0f7bc…

MALICIOUS

RTF

6.99 MB Created: 2018-08-06 06:32:00 First seen: 2020-01-07
MD5: 87a421dcf17d40d8157a0d8f1dca6585 SHA-1: 50a755b30e8f3646f9476080f2c3ae1347f8f556 SHA-256: c2728fd832f0f7bc3a2747814e3c4eee313235dc2abb93e2f85436017ee41a88
422 Risk Score
Tags
oceanlotus

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains critical vulnerabilities, CVE-2017-11882 (Equation Editor) and CVE-2017-8759 (MSXML SAX OLE activation), which are commonly exploited to deliver malicious payloads. The presence of OLE object data and a large amount of hex-encoded data within the RTF further suggests the embedding of a secondary stage. ClamAV also detected this as Rtf.Dropper.Agent, indicating its function as a dropper.

Heuristics 11

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
    RTF contains a hex-encoded OLE1 object for Msxml2.SAXXMLReader.6.0 followed by an embedded OLE compound document, and the document requests OLE activation. This matches the RTF staging shape used for CVE-2017-8759 SOAP/WSDL parser code injection.
  • ClamAV: Rtf.Dropper.Agent-7111220-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-7111220-0
  • PEB access via FS segment (x86) high SC_PEB_ACCESS
    PEB access via FS segment (x86)
    Disassembly
    Attempted x86 opcode disassembly
    006FA689  64a130000000      mov eax, dword ptr fs:[0x30]
006FA68F  53                push ebx
006FA690  33db              xor ebx, ebx
006FA692  8bd3              mov edx, ebx
006FA694  895db0            mov dword ptr [ebp - 0x50], ebx
006FA697  8b400c            mov eax, dword ptr [eax + 0xc]
006FA69A  57                push edi
006FA69B  8bfb              mov edi, ebx
006FA69D  e93d0d0000        jmp 0x6fb3df
006FA6A2  58                pop eax
006FA6A3  6a04              push 4
006FA6A5  8885e7fbffff      mov byte ptr [ebp - 0x419], al
006FA6AB  58                pop eax
006FA6AC  6a6c              push 0x6c
006FA6AE  8885ecfbffff      mov byte ptr [ebp - 0x414], al
006FA6B4  58                pop eax
006FA6B5  6a4b              push 0x4b
006FA6B7  8885eefbffff      mov byte ptr [ebp - 0x412], al
006FA6BD  58                pop eax
006FA6BE  6a44              push 0x44
006FA6C0  888534fcffff      mov byte ptr [ebp - 0x3cc], al
006FA6C6  58                pop eax
006FA6C7  6a14              push 0x14
006FA6C9  88855ffcffff      mov byte ptr [ebp - 0x3a1], al
006FA6CF  8b0424            mov eax, dword ptr [esp]
006FA6D2  9c                pushfd
006FA6D3  50                push eax
006FA6D4  27                daa
006FA6D5  6698              cbw
006FA6D7  51                push ecx
006FA6D8  66f7d9            neg cx
006FA6DB  53                push ebx
006FA6DC  8d8343cbffff      lea eax, [ebx - 0x34bd]
006FA6E2  52                push edx
006FA6E3  42                inc edx
006FA6E4  99                cdq
006FA6E5  52                push edx
006FA6E6  f9                stc
006FA6E7  33d2              xor edx, edx
  • \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 ~1562KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Suspicious extracted artifact medium 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.microsoft.com/office/word/2003/wordml In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off004f20cb.bin rtf-objdata-decoded RTF \objdata at offset 0x4F20CB 33458 bytes
SHA-256: b0fe4400967ce75dca3f40a3a0a521b8aa1c491ef4f9ea4695180557dbb6a0ba
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: NOP sled, SC_PEB_ACCESS

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