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缺陷编号：wooyun-2013-022356

漏洞标题：TUNet的拒绝服务漏洞

相关厂商：清华大学

漏洞作者： cssembly

提交时间：2013-04-23 11:08

修复时间：2013-07-22 11:09

公开时间：2013-07-22 11:09

漏洞类型：拒绝服务

危害等级：中

自评Rank：10

漏洞状态：已交由第三方合作机构(cncert国家互联网应急中心)处理

漏洞来源： http://www.wooyun.org，如有疑问或需要帮助请联系 [email protected]

Tags标签： 无

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漏洞详情

披露状态：

2013-04-23： 细节已通知厂商并且等待厂商处理中
2013-04-27： 厂商已经确认，细节仅向厂商公开
2013-04-30： 细节向第三方安全合作伙伴开放
2013-06-21： 细节向核心白帽子及相关领域专家公开
2013-07-01： 细节向普通白帽子公开
2013-07-11： 细节向实习白帽子公开
2013-07-22： 细节向公众公开

简要描述：

TUNet存在拒绝服务漏洞

详细说明：

size_t __thiscall sub_4015C0(void *this, int a2, char a3, int a4)
{
  void *v4; // esi@1
  SOCKET v5; // ebx@2
  const char *v6; // eax@4
  unsigned __int32 v7; // eax@4
  u_short v8; // dx@4
  size_t v9; // ebp@6
  char *v11; // eax@9
  char *v12; // esi@10
  const char v13; // al@13
  int *v14; // ecx@14
  const char *v15; // esi@18
  unsigned int v16; // kr18_4@18
  struct sockaddr name; // [sp+10h] [bp-9BCh]@4
  int v18; // [sp+20h] [bp-9ACh]@13
  int v19; // [sp+24h] [bp-9A8h]@13
  int v20; // [sp+28h] [bp-9A4h]@13
  int v21; // [sp+2Ch] [bp-9A0h]@13
  char Str[1024]; // [sp+30h] [bp-99Ch]@6
  char Src; // [sp+430h] [bp-59Ch]@6
  struct WSAData WSAData; // [sp+830h] [bp-19Ch]@1
  int v25; // [sp+9C8h] [bp-4h]@1
  v4 = this;
  v25 = 1;
  if ( WSAStartup(0x202u, &WSAData) )
    goto LABEL_8;
  v5 = socket(2, 1, 0);
  if ( (v5 & 0x80000000u) != 0 )
  {
    CString::operator_("创建SOCKET失败");
LABEL_8:
    WSACleanup();
    LOBYTE(v25) = 0;
    sub_515C81(&a2);
    v25 = -1;
    sub_515C81(&a3);
    return 0;
  }
  v6 = (const char *)*((_DWORD *)v4 + 4);
  *(_DWORD *)&name.sa_family = 0;
  *(_DWORD *)&name.sa_data[2] = 0;
  name.sa_family = 2;
  *(_DWORD *)&name.sa_data[6] = 0;
  *(_DWORD *)&name.sa_data[10] = 0;
  v7 = inet_addr(v6);
  v8 = *((_WORD *)v4 + 2);
  *(_DWORD *)&name.sa_data[2] = v7;
  *(_WORD *)&name.sa_data[0] = htons(v8);
  if ( connect(v5, &name, 16) < 0 )
  {
    CString::operator_((LPCSTR)&unk_571438);
    goto LABEL_8;
  }
  memset(Str, 0, sizeof(Str));
  sprintf(Str, "GET %s HTTP/1.1\r\nHost: %s\r\nConnection: Close\r\n\r\n", a2, *((_DWORD *)v4 + 4));
  send(v5, Str, strlen(Str) + 1, 0);
  memset(Str, 0, sizeof(Str));
  memset(&Src, 0, 0x400u);
  v9 = recv(v5, Str, 0x3FFu, 0);
  Str[v9] = 0;
  if ( (v9 & 0x80000000u) != 0 )
  {
    CString::operator_("无数据");
    goto LABEL_8;
  }
  v11 = strstr(Str, "\r\n\r\n");
  if ( v11 )
  {
    v12 = v11 + 4;
    v9 = strlen(v11 + 4);
  }
  else
  {
    v12 = Str;
  }
  if ( strstr(Str, "Transfer-Encoding: chunked") )
  {
    v13 = *v12;
    v18 = 0;
    v19 = 0;
    v20 = 0;
    v21 = 0;
    if ( v13 )
    {
      v14 = &v18;
      do
      {
        if ( v13 == '\r' )
          break;
        if ( v13 == '\n' )
          break;
        *(_BYTE *)v14 = v13;
        v13 = v12[1];
        v14 = (int *)((char *)v14 + 1);
        ++v12;
      }
      while ( v13 );
    }
    v15 = v12 + 2;
    v9 = strtol((const char *)&v18, 0, 0x10u);
    v16 = strlen(v15) + 1;
    if ( (signed int)v9 > (signed int)(v16 - 1) )
      v9 = v16 - 1;
    strncpy(&Src, v15, v9);
  }
  else
  {
    strcpy(&Src, v12);
  }
  CString::operator_(&Src);
  closesocket(v5);
  WSACleanup();
  LOBYTE(v25) = 0;
  sub_515C81(&a2);
  v25 = -1;
  sub_515C81(&a3);
  return v9;
}


可以看到在接受到数据后，查找strstr(Str, "Transfer-Encoding: chunked")，然后根据数据格式，查找长度字段，调用v9 = strtol((const char *)&v18, 0, 0x10u)获取长度，并未校验，如果长度字符串为-1，最终if ( (signed int)v9 > (signed int)(v16 - 1) )条件不成立，因此strncpy(&Src, v15, v9)拷贝的字节数为0xFFFFFFFF，最终导致拒绝服务。
同时还发现一个小bug。

signed int __cdecl sub_406810(int a1)
{
  SOCKET v1; // esi@4
  signed int v3; // edx@10
  signed int i; // esi@10
  char v5; // al@11
  char *v6; // edx@17
  const char *v7; // edi@17
  int fromlen; // [sp+4h] [bp-11BCh]@8
  SOCKET s; // [sp+8h] [bp-11B8h]@4
  int v10; // [sp+Ch] [bp-11B4h]@10
  struct sockaddr name; // [sp+10h] [bp-11B0h]@4
  struct sockaddr from; // [sp+20h] [bp-11A0h]@9
  char lParam[2048]; // [sp+30h] [bp-1190h]@9
  struct WSAData WSAData; // [sp+830h] [bp-990h]@1
  char v15[2048]; // [sp+9C0h] [bp-800h]@10
  if ( WSAStartup(0x202u, &WSAData)
    || (_BYTE)WSAData.wVersion != 2
    || HIBYTE(WSAData.wVersion) != (_BYTE)WSAData.wVersion )
  {
    sub_5138E0((void *)a1, "监听初始化失败", 0, 0);
    goto LABEL_37;
  }
  v1 = socket(2, 2, 0);
  s = v1;
  *(_DWORD *)&name.sa_data[2] = 0;
  name.sa_family = 2;
  *(_WORD *)&name.sa_data[0] = ntohs(10333u);
  if ( v1 != -1 )
  {
    if ( bind(v1, &name, 16) )
    {
      sub_5138E0((void *)a1, "SOCKET 绑定失败", 0, 0);
      WSACleanup();
      return -1;
    }
    fromlen = 16;
    while ( 1 )
    {
      do
      {
        memset(lParam, 0, sizeof(lParam));
        memset(&from, 0, fromlen);
        recvfrom(s, lParam, 2048, 0, &from, &fromlen);
      }
      while ( strcmp(cp, inet_ntoa(*(struct in_addr *)&from.sa_data[2])) );
      memset(v15, 0, sizeof(v15));
      sscanf(lParam, "%d&%s", &v10, v15);
      memset(lParam, 0, sizeof(lParam));
      v3 = 0;
      for ( i = 0; i < (signed int)strlen(v15); ++i )
      {
        v5 = v15[i];
        if ( v5 == '`' )
        {
          lParam[v3++] = '\r';
          lParam[v3] = '\n';
        }
        else
        {
          lParam[v3] = v5;
        }
        ++v3;
        if ( v3 >= 2048 )
          break;
      }
      if ( strcmp(lParam, "timeout_error") )
      {
        if ( strcmp(lParam, "time_policy_error") )
        {
          if ( strcmp(lParam, "max_flux_error") )
          {
            if ( strcmp(lParam, "max_hours_error") )
            {
              if ( strcmp(lParam, "remain_seconds_error") )
              {
                if ( strcmp(lParam, "remain_flux_error") )
                {
                  if ( strcmp(lParam, "flux_switch_error") )
                  {
                    if ( strcmp(lParam, "timelong_switch_error") )
                      goto LABEL_33;
                    v6 = lParam;
                    v7 = "额定时长用尽，计费组已切换。";
                  }
                  else
                  {
                    v6 = lParam;
                    v7 = "额定流量用尽，计费组已切换。";
                  }
                }
                else
                {
                  v6 = lParam;
                  v7 = (const char *)&unk_571FB0;
                }
              }
              else
              {
                v6 = lParam;
                v7 = (const char *)&unk_571FEC;
              }
            }
            else
            {
              v6 = lParam;
              v7 = (const char *)&unk_57202C;
            }
          }
          else
          {
            v6 = lParam;
            v7 = (const char *)&unk_57206C;
          }
        }
        else
        {
          v6 = lParam;
          v7 = (const char *)&unk_5720AC;
        }
      }
      else
      {
        v6 = lParam;
        v7 = (const char *)&unk_5720FC;
      }
      strcpy(v6, v7);
LABEL_33:
      if ( !v10 )
      {
        SendMessageA(*(HWND *)(a1 + 28), 0x465u, 5u, 0);
        SendMessageA(*(HWND *)(*(_DWORD *)(a1 + 596) + 28), 0x465u, 5u, 0);
      }
      SendMessageA(*(HWND *)(a1 + 28), 0x465u, 3u, (LPARAM)lParam);
    }
  }
  sub_5138E0((void *)a1, "SOCKET创建失败", 0, 0);
LABEL_37:
  WSACleanup();
  return -1;
}


其中for循环处理过程存在bug，能够覆盖返回地址的一个字节。当v15的数据为'\x60' * 1023 + 'A' + '\x60'时就能触发此bug

for ( i = 0; i < (signed int)strlen(v15); ++i )
      {
        v5 = v15[i];
        if ( v5 == 0x60 )
        {
          lParam[v3++] = '\r';
          lParam[v3] = '\n';
        }
        else
        {
          lParam[v3] = v5;
        }
        ++v3;
        if ( v3 >= 2048 )
          break;
      }

漏洞证明：

依旧没有POC

修复方案：

版权声明：转载请注明来源 cssembly@乌云

漏洞回应

厂商回应：

危害等级：高

漏洞Rank：11

确认时间：2013-04-27 22:37

厂商回复：

最新状态：

暂无

漏洞评价：

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