Bug Hunter Diary

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Stack beforethe overflowStack afterthe overflow“…\Install”savedreturnaddressuser-controlleddataSubKey(260 bytes)writing directionSubKey (260 bytes)“SOFTWARE\Webex\UCF\Components\Authoring\...”Figure 5-10: Diagram of the stack buffer overflow that occurs when an overly long stringis passed to NewObject()5.2 ExploitationAfter I found the vulnerability, exploitation was easy. All I had to dowas tweak the length of the string argument supplied to NewObject() tooverflow the stack buffer and gain control of the return address of thecurrent stack frame.As illustrated in Figure 5-9, the distance from the SubKey bufferto the saved return address on the stack is 272 bytes (the offset of thesaved return address (+00000004) minus the offset of SubKey (-0000010C):0x4 - -0x10c = 0x110 (272)). I also had to account for the fact thatthe string “Authoring” and part of the format string will be copiedinto SubKey right before the user-controlled data (see Figure 5-10).All in all I had to subtract 40 bytes (“SOFTWARE\Webex\UCF\Components\Authoring\”) from the distance between SubKey and the saved returnaddress (272 – 40 = 232). So I had to provide 232 bytes of dummydata to fill the stack and reach the saved return address. The following4 bytes of the user-controlled data should then overwrite thevalue of the saved return address on the stack.So I changed the number of supplied characters in line 6of webex_poc1.html and named the new file webex_poc2.html (seeListing 5-5):01 02 WebEx PoC 203 04 82 Chapter 5
05 06 arg = String(232, "A") + String(4, "B")07 obj.NewObject arg08 09 10 Listing 5-5: HTML file that passes an overly long string to the NewObject() method (webex_poc2.html )Then, I adjusted the little Python web server to serve the newHTML file.The original wwwserv.py:09 f = open(curdir + sep + "webex_poc1.html")The adjusted wwwserv.py:09 f = open(curdir + sep + "webex_poc2.html")I restarted the web server, loaded Internet Explorer in WinDbg,and navigated to http://www.webex.com/ again.As illustrated in Figure 5-11, I now had full control over EIP. Thebug could be easily exploited for arbitrary code execution using thewell-known heap spraying technique.Figure 5-11: EIP control of Internet ExplorerBrowse and You’re Owned 83
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A Bug Hunter’s Diary. Copyright
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Chapter 3: Escape from the WWW Zone
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B.2 The Windows Debugger (WinDbg) .
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IntroductionWelcome to A Bug Hunter
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1Bug HuntingBug hunting is the proc
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After I’ve found a bug, I want to
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Table 1-1: Debuggers Used in This B
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2Back to the ’90sSunday, October
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16361637 /* clear the SEQ table */1
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If a TiVo file is loaded by VLC, th
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Get the →vulnerableWindows versio
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EIP = 41414141 . . . Mission EIP co
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NoteTo configure Process Explorer t
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See the following excerpt from the
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3. Immunity Debugger is a great Win
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NoteInput/output controls (IOCTLs)
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msgbb_datapdatabb_rptrdb_basedatabu
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8180 /*8181 * Null terminate the st
Page 46 and 47: 26736 /*26737 * SIOC[GS]TUNPARAM ap
Page 48 and 49: 19165 * are also rejected as they i
Page 50 and 51: 01 #include 02 #include 03 #include
Page 52 and 53: fffffe8000f7e4b0 unix:die+da ()ffff
Page 54 and 55: zero pagenot mappedzero pageis mapp
Page 56 and 57: gaining full control over EIP/RIP a
Page 58 and 59: 112 return 1;113 }114115 printf ("O
Page 60 and 61: solaris$ isainfo -b64I then compile
Page 62 and 63: ip_output+0x10()ip_wput+0x37()putne
Page 64 and 65: Notes1. The source code of OpenSola
Page 66 and 67: 4.1 Vulnerability DiscoveryTo find
Page 68 and 69: 167 if (current_track + 1 > fourxm-
Page 71 and 72: Step 1: Find a Sample 4X Movie File
Page 73 and 74: Next, I modified the values of trac
Page 75 and 76: Table 4-2: List of the Assembler In
Page 77 and 78: 63 #elif defined (HAVE_MEMALIGN)64
Page 79 and 80: linux$ gdb -q ./ffmpeg_g(gdb) run -
Page 81 and 82: (UINT_MAX / sizeof(AudioTrack) - 1)
Page 83 and 84: 7ebe000-b7ec0000 r--p 0015c000 08:0
Page 85 and 86: 5Browse and You’re OwnedSunday, A
Page 87 and 88: {SWI.ClassId_q.ClassId clsid = new
Page 89 and 90: 27 except KeyboardInterrupt:28 prin
Page 91 and 92: Figure 5-4: Defining a breakpoint a
Page 93 and 94: Figure 5-7: User-controlled argumen
Page 95: Next, I tried to retrieve the size
Page 99: iDefense VCPnotifiedVulnerability d
Page 102 and 103: 6.1 Vulnerability DiscoveryI used t
Page 104 and 105: Step 3: Check the Device Security S
Page 106 and 107: Below, the elements of the MajorFun
Page 108 and 109: At address .text:00010748, a pointe
Page 110 and 111: [..][..]//// Current stack location
Page 112 and 113: The transfer type is specified usin
Page 114 and 115: If the requested IOCTL code matches
Page 116 and 117: Figure 6-5: Graph view of the vulne
Page 118 and 119: .text:00010DBA push 1 ; _DWORD.text
Page 120 and 121: 99 // .text:00010DEF cmp dword ptr
Page 122 and 123: nt!RtlpBreakWithStatusInstruction:8
Page 124 and 125: After I gained control over EIP, I
Page 127 and 128: 7A Bug Older Than 4.4BSDSaturday, M
Page 129 and 130: Here are some examples:Source code
Page 131 and 132: 1094 return (ENXIO);1095 if (t != t
Page 133 and 134: 4. The assumed address of l_open()
Page 135 and 136: osx$ cat /Library/Logs/panic.logSat
Page 137 and 138: Back on the Linux host, I started t
Page 139 and 140: 0x35574c, the value is used to calc
Page 141 and 142: 48 define search_memloc49 set $max_
Page 143 and 144: As the debugger output shows, the E
Page 145: ApplenotifiedApple asks formore det
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I performed the following steps whe
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I then began fuzzing files of the A
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Figure 8-1: Playing the unmodifiedA
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• Line 40 copies the current proc
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As the debugger output shows, media
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The manipulated byte (0xff) that ca
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(gdb) x/12x 0x1301bfc0x1301bfc: 0x0
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ApplenotifiedApple confirmsthe vuln
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Every function of a process that is
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eip 0x43434343 0x43434343eflags 0x1
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The access violation is caused when
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is less than 12. If it is, the stri
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The program in Listing A-4 calls th
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0x080483f3 : mov DWORD PTR [esp+0x4
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BDebuggingThis appendix contains in
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Information CommandsCommandDescript
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Information CommandsCommandrkbu add
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Figure B-3: Configuration settings
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Figure B-6: Attaching the kernel de
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Other CommandsCommandset disassembl
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linux# pwd/home/tk/gdb-292/srclinux
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Notes1. See the Solaris Modular Deb
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The many mitigation techniques coul
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Figure C-1: DEP and ASLR status sho
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08 p[0] = 0x41414141;09 printf (“
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ConclusionIn case of a buffer overf
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zonecfg:wwwzone> set autoboot=truez
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Notes1. See Rob King, “New Leopar
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COMRaider, 72coordinated disclosure
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Rreadelf, 161RELRO, 67-69, 183-186r
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A Bug Hunter’s Diary is set in Ne
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