diff --git a/Dockerfile b/Dockerfile
index fb991f9..67235ca 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM python:3.11-slim AS build
+FROM python:3.14-slim AS build
WORKDIR /
diff --git a/README.md b/README.md
index ced6f7b..f253234 100644
--- a/README.md
+++ b/README.md
@@ -73,13 +73,13 @@ Here is a batch of usefull commands.
```bash
docker compose down -v # Remove volume containings results
-docker compose -f docker-compose-dev.yml up # Start application in developpement mode
+docker compose -f compose.dev.yml up # Start application in developpement mode
rm -rf aperisolve/results # Remove results from developpement mode
docker exec -it postgres psql -U aperiuser -d aperisolve # Get postgresql shell
docker exec -it aperisolve-web bash # Get shell in running web app
```
-> Note, if you used [docker-compose-dev.yml](docker-compose-dev.yml), you must remove "results" when switching to [production docker](docker-compose.yml).
+> Note, if you used [compose.dev.yml](compose.dev.yml), you must remove "results" when switching to [production docker](compose.yml).
### Code quality
@@ -94,7 +94,6 @@ GitHub CI will alert in case of failure.
## Roadmap
-- [x] PngCheck
- [ ] Zsteg extract / --all --> **Download `zsteg` files** such as mp3 encoded on LSB
- [ ] Test on mobile
- [ ] i18n
diff --git a/aperisolve/analyzers/image_resize.py b/aperisolve/analyzers/image_resize.py
new file mode 100644
index 0000000..1a8f5e7
--- /dev/null
+++ b/aperisolve/analyzers/image_resize.py
@@ -0,0 +1,190 @@
+"""Image size bruteforcer for common PNG sizes."""
+
+import zlib
+import shutil
+from pathlib import Path
+from .utils import update_data
+
+# Full list of expected sizes
+EXPECTED_SIZES = [
+ # -------------------------
+ # ICONS (Square)
+ # -------------------------
+ (16, 16), (20, 20), (24, 24), (28, 28),
+ (32, 32), (48, 48), (64, 64), (72, 72),
+ (96, 96), (128, 128), (192, 192), (256, 256),
+ (384, 384), (512, 512), (768, 768), (1024, 1024),
+ (1536, 1536), (2048, 2048), (4096, 4096),
+
+ # -------------------------
+ # 1:1 Square (General)
+ # -------------------------
+ (300, 300), (500, 500), (800, 800), (1000, 1000),
+ (1500, 1500), (2000, 2000), (2500, 2500), (3000, 3000),
+
+ # -------------------------
+ # 4:3 Aspect (Classic Screens)
+ # -------------------------
+ (320, 240), (640, 480), (800, 600), (960, 720),
+ (1024, 768), (1280, 960), (1600, 1200), (2048, 1536),
+ (2560, 1920), (3200, 2400), (4096, 3072),
+
+ # -------------------------
+ # 3:2 Aspect (Photography)
+ # -------------------------
+ (600, 400), (900, 600), (1200, 800), (1500, 1000),
+ (1800, 1200), (2400, 1600), (3000, 2000), (3600, 2400),
+ (4500, 3000), (6000, 4000),
+
+ # -------------------------
+ # 16:9 Aspect (Video / Web)
+ # -------------------------
+ (426, 240), (640, 360), (854, 480), (960, 540),
+ (1280, 720), (1366, 768), (1600, 900), (1920, 1080),
+ (2560, 1440), (3200, 1800), (3440, 1935), (3840, 2160),
+ (5120, 2880), (7680, 4320), (10240, 5760),
+
+ # -------------------------
+ # 16:10 Aspect (Laptops)
+ # -------------------------
+ (1280, 800), (1440, 900), (1680, 1050),
+ (1920, 1200), (2560, 1600), (2880, 1800),
+ (3840, 2400), (5120, 3200),
+
+ # -------------------------
+ # Mobile Portrait (9:16)
+ # -------------------------
+ (720, 1280), (1080, 1920), (1440, 2560),
+ (2160, 3840), (1440, 2960), (1080, 2400),
+ (1170, 2532), (1284, 2778), (1290, 2796),
+
+ # -------------------------
+ # Social Media Sizes
+ # -------------------------
+ # Instagram
+ (1080, 1080), (1080, 1350), (1080, 1920),
+
+ # Facebook
+ (1200, 628), (1200, 1200),
+
+ # Twitter/X
+ (1200, 675), (1500, 500),
+
+ # YouTube Thumbnails
+ (1280, 720), (1920, 1080),
+
+ # -------------------------
+ # Banners / Headers
+ # -------------------------
+ (1600, 500), (1920, 500), (2560, 700),
+ (3000, 1000), (3840, 1200),
+
+ # -------------------------
+ # Print-like Digital Sizes
+ # -------------------------
+ (2550, 3300), # Letter @ 300 DPI
+ (2480, 3508), # A4 @ 300 DPI
+ (3508, 4961), # A3 @ 300 DPI
+ (4961, 7016), # A2 @ 300 DPI
+ (7016, 9933), # A1 @ 300 DPI
+
+]
+
+def calc_checksum(header_chunk, width_bytes, height_bytes):
+ """
+ Calculates the CRC32 of the IHDR chunk with new dimensions.
+ header_chunk: The full IHDR chunk (Type + Data).
+ """
+ # Reconstruct IHDR: [Type(4)] + [New Width(4)] + [New Height(4)] + [Rest of Data(5)]
+ new_header = header_chunk[:4] + width_bytes + height_bytes + header_chunk[12:]
+
+ # Calculate CRC and return as 4 bytes (Big Endian)
+ return bytearray((zlib.crc32(new_header) & 0xffffffff).to_bytes(4, byteorder='big'))
+
+def analyze_image_resize(input_img: Path, output_dir: Path) -> None:
+ """
+ Analyze an image submission using python-based resize bruteforce.
+ Attempts to recover PNGs with modified resolutions but valid CRCs.
+ """
+
+ # 1. Setup Paths
+ input_img = Path(input_img)
+ output_dir = Path(output_dir)
+
+ # 3. Initialize Logs
+ logs = []
+ recovered_image = None
+
+ try:
+ with input_img.open("rb") as image:
+ f = image.read()
+
+ b = bytearray(f)
+
+ # Find IHDR start
+ IHDR = b.find(b'\x49\x48\x44\x52')
+ if IHDR == -1:
+ logs.append("Failure: PNG header (IHDR) not found.")
+ update_data(output_dir, {"image_resize": {"status": "error", "error": "PNG header not found."}})
+ return
+
+ # Calculate Chunk Length (The 4 bytes BEFORE IHDR tag)
+ chunk_length = int.from_bytes((b[IHDR- 4: IHDR]), byteorder="big") + 4
+
+ # Extract Target CRC (The 4 bytes AFTER the chunk data)
+ target_crc = b[IHDR + chunk_length:IHDR + chunk_length + 4]
+
+ # Isolate the header chunk (Type + Data)
+ header_chunk = b[IHDR:IHDR + chunk_length]
+
+ logs.append(f"Target CRC found: 0x{target_crc.hex()}")
+
+ match_found = False
+
+ # Brute-force Loop
+ for size in EXPECTED_SIZES:
+ width, height = size
+
+ # Convert dimensions to 4-byte Big Endian arrays
+ width_bytes = bytearray(width.to_bytes(4, byteorder='big'))
+ height_bytes = bytearray(height.to_bytes(4, byteorder='big'))
+
+ # Check if this size matches the file's CRC
+ if target_crc == calc_checksum(header_chunk, width_bytes, height_bytes):
+ match_found = True
+ logs.append(f"Success: Match found! Dimensions: {width}x{height}")
+
+ # Create Output Filename
+ img_name = f"recovered_{width}x{height}.png"
+
+ # Create parent directories if they don't exist
+ output_dir.mkdir(parents=True, exist_ok=True)
+ output_path = output_dir / img_name
+
+ # Splicing: [Start...IHDR+4] + [W] + [H] + [IHDR+12...End]
+ full_png_data = b[:IHDR+4] + width_bytes + height_bytes + b[IHDR+12:]
+
+ # Write the recovered file to disk
+ with output_path.open("wb") as out_f:
+ out_f.write(full_png_data)
+
+ recovered_image = Path(output_dir.name) / img_name
+ break # Stop looking after finding the match
+
+ if not match_found:
+ logs.append("Failure: No matching dimensions found.")
+
+ # 4. Final Data Update
+ output_data = {
+ "image_resize": { # Key name must match your module name in AperiSolve
+ "status": "ok",
+ "output": logs
+ }
+ }
+ if recovered_image:
+ output_data["image_resize"]["image"] = "/image/" + str(recovered_image)
+ update_data(output_dir, output_data)
+
+ except Exception as e:
+ update_data(output_dir, {"image_resize": {"status": "error", "error": str(e)}})
+ return None
\ No newline at end of file
diff --git a/aperisolve/config.py b/aperisolve/config.py
index 89f3350..fe000d3 100644
--- a/aperisolve/config.py
+++ b/aperisolve/config.py
@@ -3,6 +3,6 @@
from pathlib import Path
IMAGE_EXTENSIONS = [".png", ".jpg", ".jpeg", ".gif", ".bmp", ".webp", ".tiff"]
-WORKER_FILES = ["binwalk", "foremost", "steghide", "zsteg"]
+WORKER_FILES = ["binwalk", "foremost", "steghide", "zsteg", "image_resize"]
RESULT_FOLDER = Path(__file__).parent.resolve() / "results"
diff --git a/aperisolve/static/js/aperisolve.js b/aperisolve/static/js/aperisolve.js
index 3127aa6..771bfa8 100644
--- a/aperisolve/static/js/aperisolve.js
+++ b/aperisolve/static/js/aperisolve.js
@@ -8,6 +8,7 @@ const TOOL_ORDER = [
"steghide",
"zsteg",
"strings",
+ "image_resize",
];
function escapeHtml(text) {
@@ -248,7 +249,7 @@ function parseResult(result) {
analyzer.className = `analyzer a-${escapeHtml(tool)}`;
resultDiv.appendChild(analyzer);
- analyzer.innerHTML += `${capitalize(tool)}
`;
+ analyzer.innerHTML += `${capitalize(tool.replace("_"," "))}
`;
if (result[tool]["status"] === "ok") {
if ("images" in result[tool]) {
@@ -270,7 +271,16 @@ function parseResult(result) {
}
}
}
+
+ if ("image" in result[tool]) {
+ // Parse image output
+ analyzer.innerHTML += ``;
+ }
+
// Parse text output
+
if (typeof result[tool]["output"] === "string") {
analyzer.innerHTML += `${escapeHtml(
diff --git a/aperisolve/templates/faq.html b/aperisolve/templates/faq.html
index 2b72bff..ccf4083 100644
--- a/aperisolve/templates/faq.html
+++ b/aperisolve/templates/faq.html
@@ -6,8 +6,8 @@
This cheatsheet is intended to guide CTF players in their research. This cheatsheet is not representative of
- modern steganography/seganalysis techniques, and its content does not match with the creation of an interesting
- challenges 😉.
+ modern steganography/steganalysis techniques, and its content does not match with the creation of an interesting
+ challenge 😉.
Check file type / metadata
@@ -48,7 +48,7 @@
- Verify the checksums of the file. These are usually CRC32, some tools like PngCheck or PCRT are usefull to verify and
+ href='https://github.com/sherlly/PCRT' target='_blank' class='highlight'>PCRT are useful to verify and
correct these checksums.
@@ -176,7 +176,7 @@ print(pxs[:10])'>
in the file (strings & exiftool), or the object
represented by the image. In some cases, the password cannot be retrieved and a bruteforce must be performed.
The tool StegCracker
- and Stegbrute allows
+ and Stegbrute allows
bruteforce of hidden secrets with Steghide.
@@ -406,4 +406,4 @@ print(pxs[:10])'>
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/aperisolve/workers.py b/aperisolve/workers.py
index 963bb1e..956c328 100644
--- a/aperisolve/workers.py
+++ b/aperisolve/workers.py
@@ -13,6 +13,7 @@ from .analyzers.steghide import analyze_steghide
from .analyzers.strings import analyze_strings
from .analyzers.zsteg import analyze_zsteg
from .analyzers.pngcheck import analyze_pngcheck
+from .analyzers.image_resize import analyze_image_resize
from .app import app, db
from .config import RESULT_FOLDER
from .models import Image, Submission
@@ -53,6 +54,7 @@ def analyze_image(submission_hash: str) -> None:
(analyze_pngcheck, img_path, result_path),
(analyze_steghide, img_path, result_path, submission.password),
(analyze_zsteg, img_path, result_path),
+ (analyze_image_resize, img_path, result_path),
]
# Deep analysis only
diff --git a/docker-compose-dev.yml b/compose.dev.yml
similarity index 100%
rename from docker-compose-dev.yml
rename to compose.dev.yml
diff --git a/docker-compose.yml b/compose.yml
similarity index 100%
rename from docker-compose.yml
rename to compose.yml