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🛡️ Sentinel: [HIGH] Fix Markdown injection in Telegram messages #2

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🛡️ Sentinel: [HIGH] Fix Markdown injection in Telegram messages #2

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4 changes: 4 additions & 0 deletions .jules/sentinel.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
## 2024-05-23 - Markdown Injection in Telegram Messages
**Vulnerability:** User-controlled input (usernames, search queries, article titles) was directly inserted into Markdown-formatted messages without escaping.
**Learning:** Even in non-web applications like Telegram bots, input validation and output encoding are critical. Unescaped characters like `*` and `_` can break message formatting, leading to denial of service (message send failure) or spoofing.
**Prevention:** Always escape user input before interpolating it into message templates. Use a helper function like `escape_markdown_v1` for Legacy Markdown mode.
22 changes: 22 additions & 0 deletions functions/security_utils.py
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"""
Security Utility Functions
"""

import re

def escape_markdown_v1(text: str) -> str:
"""
Helper function to escape telegram markup symbols.
Escapes: '_', '*', '`', '['
"""
if not text:
return ""
# Escape markdown characters
escape_chars = r'[_*`\[]'
return re.sub(f'({escape_chars})', r'\\\1', str(text))

def sanitize_html(text: str) -> str:
"""
Sanitize HTML tags from text.
"""
return re.sub(r'<[^>]*>', '', text)
35 changes: 23 additions & 12 deletions functions/telegram_bot.py
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Expand Up @@ -46,6 +46,7 @@ async def start_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
"""Handle /start command - welcome message."""
from .user_storage import get_user_language
from .translations import t
from .security_utils import escape_markdown_v1

user = update.effective_user
telegram_id = user.id
Expand All @@ -59,7 +60,7 @@ async def start_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
except Exception as e:
print(f"Database not available (running locally?): {e}")

welcome_message = t('welcome', user_lang, username=username)
welcome_message = t('welcome', user_lang, username=escape_markdown_v1(username))
await update.message.reply_text(
welcome_message,
parse_mode='Markdown'
Expand Down Expand Up @@ -541,6 +542,7 @@ async def saved_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
"""Handle /saved command - show saved articles with delete buttons."""
from .user_storage import get_saved_articles, get_user_language
from .translations import t
from .security_utils import escape_markdown_v1
import hashlib

telegram_id = update.effective_user.id
Expand All @@ -562,6 +564,7 @@ async def saved_command(update: Update, context: ContextTypes.DEFAULT_TYPE):

for i, article in enumerate(articles, 1):
title = article.get('title', 'Untitled')[:50]
safe_title = escape_markdown_v1(title)
url = article.get('url', '')
source = article.get('source', '')
category = article.get('category', 'tech')
Expand All @@ -575,9 +578,9 @@ async def saved_command(update: Update, context: ContextTypes.DEFAULT_TYPE):

# Build message line
if url.startswith('http'):
message += f"{i}. {emoji} [{title}]({url})"
message += f"{i}. {emoji} [{safe_title}]({url})"
else:
message += f"{i}. {emoji} {title}"
message += f"{i}. {emoji} {safe_title}"

if date_str:
message += f" `{date_str}`"
Expand Down Expand Up @@ -643,6 +646,7 @@ async def filter_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
"""Handle /filter command - filter saved articles by category."""
from .user_storage import get_saved_articles, get_user_language
from .translations import t
from .security_utils import escape_markdown_v1

telegram_id = update.effective_user.id
user_lang = get_user_language(telegram_id)
Expand Down Expand Up @@ -675,11 +679,12 @@ async def filter_command(update: Update, context: ContextTypes.DEFAULT_TYPE):

for i, article in enumerate(articles, 1):
title = article.get('title', 'Untitled')[:50]
safe_title = escape_markdown_v1(title)
url = article.get('url', '')
if url.startswith('http'):
message += f"{i}. [{title}]({url})\n"
message += f"{i}. [{safe_title}]({url})\n"
else:
message += f"{i}. {title}\n"
message += f"{i}. {safe_title}\n"

try:
await update.message.reply_text(message, parse_mode='Markdown', disable_web_page_preview=True)
Expand All @@ -691,6 +696,7 @@ async def recap_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
"""Handle /recap command - show weekly summary of saved articles."""
from .user_storage import get_saved_articles, get_user_language
from .translations import t
from .security_utils import escape_markdown_v1
from datetime import datetime, timedelta

telegram_id = update.effective_user.id
Expand Down Expand Up @@ -728,14 +734,15 @@ async def recap_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
# Show top 5 recent articles
for i, article in enumerate(weekly_articles[:5], 1):
title = article.get('title', 'Untitled')[:50]
safe_title = escape_markdown_v1(title)
url = article.get('url', '')
category = article.get('category', 'tech')
emoji = cat_emoji.get(category, '🔧')

if url.startswith('http'):
message += f"{i}. {emoji} [{title}]({url})\n"
message += f"{i}. {emoji} [{safe_title}]({url})\n"
else:
message += f"{i}. {emoji} {title}\n"
message += f"{i}. {emoji} {safe_title}\n"

message += f"\n_Total: {len(weekly_articles)} articles this week_"

Expand Down Expand Up @@ -797,6 +804,7 @@ async def search_command(update: Update, context: ContextTypes.DEFAULT_TYPE):
from .user_storage import add_search_history, get_user_language
from .rate_limiter import check_rate_limit
from .translations import t
from .security_utils import escape_markdown_v1

telegram_id = update.effective_user.id
user_lang = get_user_language(telegram_id)
Expand Down Expand Up @@ -827,7 +835,8 @@ async def search_command(update: Update, context: ContextTypes.DEFAULT_TYPE):

add_search_history(telegram_id, query)

await update.message.reply_text(t('searching', user_lang, query=query), parse_mode='Markdown')
safe_query = escape_markdown_v1(query)
await update.message.reply_text(t('searching', user_lang, query=safe_query), parse_mode='Markdown')

try:
# Fetch news
Expand All @@ -837,25 +846,27 @@ async def search_command(update: Update, context: ContextTypes.DEFAULT_TYPE):

# Filter by query
results = []
query_lower = query.lower()
for article in all_news:
title = article.get('title', '').lower()
if query in title or any(word in title for word in query.split()):
if query_lower in title or any(word in title for word in query_lower.split()):
results.append(article)

if not results:
await update.message.reply_text(
t('no_results', user_lang, query=query),
t('no_results', user_lang, query=safe_query),
parse_mode='Markdown'
)
return

# Format results
message = t('search_results', user_lang, query=query, count=len(results))
message = t('search_results', user_lang, query=safe_query, count=len(results))
for i, article in enumerate(results[:10], 1):
title = article.get('title', '')[:60]
safe_title = escape_markdown_v1(title)
url = article.get('url', '')
source = article.get('source', '')
message += f"{i}. [{title}]({url}) _{source}_\n"
message += f"{i}. [{safe_title}]({url}) _{source}_\n"

await update.message.reply_text(
message,
Expand Down