TippingPoint Digital Vaccine Laboratories
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Trend Micro ServerProtect eng50.dll Stack Overflow Vulnerabilities

TPTI-07-02: February 20th, 2007


Affected Vendors

Affected Products

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 5101. For further product information on the TippingPoint IPS:

Vulnerability Details

These vulnerabilities allow attackers to execute arbitrary code on vulnerable installations of Trend Micro ServerProtect. Authentication is not required to exploit these vulnerabilities.

The specific flaws exist within the StCommon.dll library and are reachable remotely through a DCE/RPC endpoint on TCP port 5168 bound to by the service SpntSvc.exe. The RPC endpoint is exposed from TmRpcSrv.dll with the following IDL stub information:

// opcode: 0x00, address: 0x65741030
// uuid: 25288888-bd5b-11d1-9d53-0080c83a5c2c
// version: 1.0

error_status_t rpc_opnum_0 (
[in] handle_t arg_1,
[in] long trend_req_num,
[in][size_is(arg_4)] byte overflow_str[],
[in] long arg_4,
[out][size_is(arg_6)] byte arg_5[],
[in] long arg_6

The upper half of the 'trend_req_num' DWORD RPC argument from above is used within TmRpcSrv.dll as an index into a call table. It must specifically be 0x0003 which results in a call to StRpcSrv.65671000(). The original arguments to the RPC endpoint are then passed to this called routine:

657416E6 mov eax, opnum0_call_table[eax*4]
657416ED test eax, eax
657416EF jnz short loc_65741707
65741707 loc_65741707:
65741707 mov [ebp+var_4], 0
6574170E mov edx, [ebp+sizeof_arg5]
65741711 push edx
65741712 mov edx, [ebp+arg5_array]
65741715 push edx
65741716 mov edx, [ebp+sizeof_overflow_str]
65741719 push edx
6574171A mov edx, [ebp+overflow_str]
6574171D push edx
6574171E push ecx ; trend_req_num
6574171F call eax ; call handler

The lower half of the 'trend_req_num' DWORD RPC argument is then used within StRpcSrv.dll as an index into a second call table. The value of this lower half controls the code flow to the following vulnerabilities and is hereto referred to as the 'subcode'.

--[ Vulnerability One
A subcode value of 0x0004 results in a call to ENG_SetRealTimeScanConfigInfo() which subsequently calls through Eng50.61181940() -> Eng50.611819E0() -> Eng50.61190F60() and can result in a stack overflow due to an unbounded widechar string copy into a ~600 byte stack-based buffer as shown in the following relevant excerpt:

61190FC7 lea edx, [esp+288h+szShortPath]
61190FCB push esi
61190FCC push edx
61190FCD call _wcscpy

--[ Vulnerability Two
A subcode value of 0x0047 results in a call to ENG_SendEMail() which can result in a stack overflow due to an unbounded widechar string copy into a ~2k stack-based buffer as shown in the following relevant excerpt:

6118A161 mov esi, [esp+780h+arg_0]
6118A168 lea eax, [esp+780h+var_778]
6118A16C push esi
6118A16D push eax
6118A16E call _wcscpy

The resulting stack overflows can be leveraged to execute arbitrary code under the privileges of the SYSTEM user.

Vendor Response

Trend Micro has issued an update to correct this vulnerability. More details can be found at:

Disclosure Timeline

    2007-02-01 - Vulnerability reported to vendor
    2007-02-20 - Coordinated public release of advisory


This vulnerability was discovered by: