Bug Hunter Diary

Recommendations

Info

In sub_1000767F the user-provided wide-character string is convertedto a character string using the WideCharToMultiByte() function.After that, sub_10009642 is called, and the user-controlled characterstring is copied into another buffer. The code in sub_10009642 allowsa maximum of 256 user-controlled bytes to be copied into this newcharacter buffer (pseudo C code: strncpy (new_buffer, user_controlled_string, 256)). The function sub_10009826 is called, and it calls sub_100096D0,which then calls the vulnerable function sub_1000B37D.[..].text:1000B37D ; int __cdecl sub_1000B37D(DWORD cbData, LPBYTE lpData, int, int, int).text:1000B37D sub_1000B37D proc near.text:1000B37D.text:1000B37D SubKey= byte ptr -10Ch.text:1000B37D Type= dword ptr -8.text:1000B37D hKey= dword ptr -4.text:1000B37D cbData= dword ptr 8.text:1000B37D lpData= dword ptr 0Ch.text:1000B37D arg_8= dword ptr 10h.text:1000B37D arg_C= dword ptr 14h.text:1000B37D arg_10= dword ptr 18h.text:1000B37D.text:1000B37D push ebp.text:1000B37E mov ebp, esp.text:1000B380 sub esp, 10Ch.text:1000B386 push edi.text:1000B387 lea eax, [ebp+SubKey] ; the address of SubKey is saved in eax.text:1000B38D push [ebp+cbData] ; 4th parameter of sprintf(): cbData.text:1000B390 xor edi, edi.text:1000B392 push offset aAuthoring ; 3rd parameter of sprintf(): "Authoring".text:1000B397 push offset aSoftwareWebexU ; 2nd parameter of sprintf(): "SOFTWARE\\...text:1000B397; ..Webex\\UCF\\Components\\%s\\%s\\Install".text:1000B39C push eax ; 1st parameter of sprintf(): address of SubKey.text:1000B39D call ds:sprintf ; call to sprintf()[..].data:10012228 ; char aSoftwareWebexU[].data:10012228 aSoftwareWebexU db 'SOFTWARE\Webex\UCF\Components\%s\%s\Install',0[..]Listing 5-3: Disassembly of the vulnerable function sub_1000B37D (created in IDA Pro)The first argument of sub_1000B37D, called cbData, holds a pointerto the user-controlled data stored in the new character buffer (seenew_buffer in the description of Figure 5-8). As I said before, the usercontrolledwide-character data is stored in this new buffer as a characterstring with a maximum length of 256 bytes. Listing 5-3 showsthat the sprintf() function at address .text:1000B39D copies the usercontrolleddata pointed to by cbData into a stack buffer called SubKey(see .text:1000B387 and .text:1000B39C).80 Chapter 5
Next, I tried to retrieve the size of this SubKey stack buffer. I openedIDA Pro’s default stack frame displays by pressing CTRL-K. As shown inFigure 5-9, the stack buffer SubKey has a fixed size of 260 bytes. If theinformation from the disassembly shown in Listing 5-3 is combinedwith the information on the stack layout of the vulnerable function,the call to sprintf() can be expressed with the C code in Listing 5-4.Figure 5-9: Determining the size of the SubKey stack buffer using IDA Pro’s defaultstack frame displays[..]intsub_1000B37D(DWORD cbData, LPBYTE lpData, int val1, int val2, int val3){char SubKey[260];sprintf(&SubKey, "SOFTWARE\\Webex\\UCF\\Components\\%s\\%s\\Install","Authoring", cbData);[..]Listing 5-4: Pseudo C code of the vulnerable call to sprintf()The sprintf() library function copies the user-controlled datafrom cbData as well as the string “Authoring” (9 bytes) and the formatstring (39 bytes) into SubKey. If cbData is filled with the maximumamount of user-controlled data (256 bytes), a total of 304 bytes ofdata will be copied into the stack buffer. SubKey can only hold up to260 bytes, and sprintf() doesn’t perform any length check. Therefore,as shown in Figure 5-10, it’s possible to write user-controlled data outof the bounds of SubKey, which leads to a stack buffer overflow (seeSection A.1).Browse and You’re Owned 81
Page 6 and 7:
A Bug Hunter’s Diary. Copyright
Page 10 and 11:
Chapter 3: Escape from the WWW Zone
Page 12 and 13:
B.2 The Windows Debugger (WinDbg) .
Page 15 and 16:
IntroductionWelcome to A Bug Hunter
Page 17 and 18:
1Bug HuntingBug hunting is the proc
Page 19 and 20:
After I’ve found a bug, I want to
Page 21 and 22:
Table 1-1: Debuggers Used in This B
Page 23:
2Back to the ’90sSunday, October
Page 26 and 27:
16361637 /* clear the SEQ table */1
Page 28 and 29:
If a TiVo file is loaded by VLC, th
Page 30 and 31:
Get the →vulnerableWindows versio
Page 32 and 33:
EIP = 41414141 . . . Mission EIP co
Page 34 and 35:
NoteTo configure Process Explorer t
Page 36 and 37:
See the following excerpt from the
Page 38 and 39:
3. Immunity Debugger is a great Win
Page 40 and 41:
NoteInput/output controls (IOCTLs)
Page 42 and 43:
msgbb_datapdatabb_rptrdb_basedatabu
Page 44 and 45: 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: Figure 5-7: User-controlled argumen
Page 97 and 98: 05 06 arg = String(232, "A") + Stri
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
Page 148 and 149:
I performed the following steps whe
Page 150 and 151:
I then began fuzzing files of the A
Page 152 and 153:
Figure 8-1: Playing the unmodifiedA
Page 154 and 155:
• Line 40 copies the current proc
Page 156 and 157:
As the debugger output shows, media
Page 158 and 159:
The manipulated byte (0xff) that ca
Page 160 and 161:
(gdb) x/12x 0x1301bfc0x1301bfc: 0x0
Page 162 and 163:
ApplenotifiedApple confirmsthe vuln
Page 164 and 165:
Every function of a process that is
Page 166 and 167:
eip 0x43434343 0x43434343eflags 0x1
Page 168 and 169:
The access violation is caused when
Page 170 and 171:
is less than 12. If it is, the stri
Page 172 and 173:
The program in Listing A-4 calls th
Page 174 and 175:
0x080483f3 : mov DWORD PTR [esp+0x4
Page 177 and 178:
BDebuggingThis appendix contains in
Page 179 and 180:
Information CommandsCommandDescript
Page 181 and 182:
Information CommandsCommandrkbu add
Page 183 and 184:
Figure B-3: Configuration settings
Page 185 and 186:
Figure B-6: Attaching the kernel de
Page 187 and 188:
Other CommandsCommandset disassembl
Page 189 and 190:
linux# pwd/home/tk/gdb-292/srclinux
Page 191:
Notes1. See the Solaris Modular Deb
Page 194 and 195:
The many mitigation techniques coul
Page 196 and 197:
Figure C-1: DEP and ASLR status sho
Page 198 and 199:
08 p[0] = 0x41414141;09 printf (“
Page 200 and 201:
ConclusionIn case of a buffer overf
Page 202 and 203:
zonecfg:wwwzone> set autoboot=truez
Page 204 and 205:
Notes1. See Rob King, “New Leopar
Page 206 and 207:
COMRaider, 72coordinated disclosure
Page 208 and 209:
Rreadelf, 161RELRO, 67-69, 183-186r
Page 210:
A Bug Hunter’s Diary is set in Ne
show all

Bug Hunter Diary

Create successful ePaper yourself

Delete template?

Save as template?