New Zero-Day Exploit targeting Internet Explorer Versions 9 through 11 Identified in Targeted Attacks


FireEye Research Labs identified a new Internet Explorer (IE) zero-day exploit used in targeted attacks.  The vulnerability affects IE6 through IE11, but the attack is targeting IE9 through IE11.  This zero-day bypasses both ASLR and DEP. Microsoft has assigned CVE-2014-1776 to the vulnerability and released security advisory to track this issue.

Threat actors are actively using this exploit in an ongoing campaign which we have named “Operation Clandestine Fox.” However, for many reasons, we will not provide campaign details. But we believe this is a significant zero day as the vulnerable versions represent about a quarter of the total browser market. We recommend applying a patch once available.
According to NetMarket Share, the market share for the targeted versions of IE in 2013 were:

IE 9      13.9%
IE 10    11.04%
IE 11     1.32%

Collectively, in 2013, the vulnerable versions of IE accounted for 26.25% of the browser market.  The vulnerability, however, does appear in IE6 through IE11 though the exploit targets IE9 and higher.

The Details

The exploit leverages a previously unknown use-after-free vulnerability, and uses a well-known Flash exploitation technique to achieve arbitrary memory access and bypass Windows’ ASLR and DEP protections.


• Preparing the heap

The exploit page loads a Flash SWF file to manipulate the heap layout with the common technique heap feng shui. It allocates Flash vector objects to spray memory and cover address 0×18184000. Next, it allocates a vector object that contains a flash.Media.Sound() object, which it later corrupts to pivot control to its ROP chain.

• Arbitrary memory access

The SWF file calls back to Javascript in IE to trigger the IE bug and overwrite the length field of a Flash vector object in the heapspray. The SWF file loops through the heapspray to find the corrupted vector object, and uses it to again modify the length of another vector object. This other corrupted vector object is then used for subsequent memory accesses, which it then uses to bypass ASLR and DEP.

• Runtime ROP generation

With full memory control, the exploit will search for ZwProtectVirtualMemory, and a stack pivot (opcode 0×94 0xc3) from NTDLL. It also searches for SetThreadContext in kernel32, which is used to clear the debug registers. This technique, documented here, may be an attempt to bypass protections that use hardware breakpoints, such as EMET’s EAF mitigation.

With the addresses of the aforementioned APIs and gadget, the SWF file constructs a ROP chain, and prepends it to its RC4 decrypted shellcode. It then replaces the vftable of a sound object with a fake one that points to the newly created ROP payload. When the sound object attempts to call into its vftable, it instead pivots control to the attacker’s ROP chain.

• ROP and Shellcode

The ROP payload basically tries to make memory at 0×18184000 executable, and to return to 0x1818411c to execute the shellcode.

0:008> dds eax
18184100  770b5f58 ntdll!ZwProtectVirtualMemory
18184104  1818411c
18184108  ffffffff
1818410c  181840e8
18184110  181840ec
18184114  00000040
18184118  181840e4

Inside the shellcode, it saves the current stack pointer to 0×18181800 to safely return to the caller.

mov     dword ptr ds:[18181800h],ebp

Then, it restores the flash.Media.Sound vftable and repairs the corrupted vector object to avoid application crashes.

18184123 b820609f06      mov     eax,69F6020h
18184128 90              nop
18184129 90              nop
1818412a c700c0f22169    mov     dword ptr [eax],offset Flash32_11_7_700_261!AdobeCPGetAPI+0x42ac00 (6921f2c0)
18184133 b800401818      mov     eax,18184000h
18184138 90              nop
18184139 90              nop
1818413a c700fe030000    mov     dword ptr [eax],3FEh ds:0023:18184000=3ffffff0

The shellcode also recovers the ESP register to make sure the stack range is in the current thread stack base/limit.

18184140 8be5            mov     esp,ebp
18184142 83ec2c          sub     esp,2Ch
18184145 90              nop
18184146 eb2c            jmp     18184174

The shellcode calls SetThreadContext to clear the debug registers. It is possible that this is an attempt to bypass mitigations that use the debug registers.

18184174 57              push    edi
18184175 81ece0050000    sub     esp,5E0h
1818417b c7042410000100  mov     dword ptr [esp],10010h
18184182 8d7c2404        lea     edi,[esp+4]
18184186 b9dc050000      mov     ecx,5DCh
1818418b 33c0            xor     eax,eax
1818418d f3aa            rep stos byte ptr es:[edi]
1818418f 54              push    esp
18184190 6afe            push    0FFFFFFFEh
18184192 b8b308b476      mov     eax,offset kernel32!SetThreadContext (76b408b3)
18184197 ffd0            call    eax

The shellcode calls URLDownloadToCacheFileA to download the next stage of the payload, disguised as an image.


Using EMET may break the exploit in your environment and prevent it from successfully controlling your computer. EMET versions 4.1 and 5.0 break (and/or detect) the exploit in our tests.
Enhanced Protected Mode in IE breaks the exploit in our tests. EPM was introduced in IE10.
Additionally, the attack will not work without Adobe Flash. Disabling the Flash plugin within IE will prevent the exploit from functioning.

Threat Group History

The APT group responsible for this exploit has been the first group to have access to a select number of browser-based 0-day exploits (e.g. IE, Firefox, and Flash) in the past. They are extremely proficient at lateral movement and are difficult to track, as they typically do not reuse command and control infrastructure. They have a number of backdoors including one known as Pirpi that we previously discussed here. CVE-2010-3962, then a 0-day exploit in Internet Explorer 6, 7, and 8 dropped the Pirpi payload discussed in this previous case.

As this is still an active investigation we are not releasing further indicators about the exploit at this time.

Acknowledgement: We thank Christopher Glyer, Matt Fowler, Josh Homan, Ned Moran, Nart Villeneuve and Yichong Lin for their support, research, and analysis on these findings.

DLL Side-Loading: Another Blind-Spot for Anti-Virus

Last month, I presented a talk at the RSA USA Conference on an increasingly popular threat vector called “Dynamic-Link Library Side-Loading” (DLL Side-Loading). As with many vulnerabilities, this exploit has existed for a rather long time and is the result of Microsoft looking to make binary updates easier for Windows developers through the Windows side-by-side (WinSxS) assembly feature.

Now, though, advanced persistent threat (APT) developers are using the innocuous DLL Side-Loading method to sneak malware past anti-virus (AV) scanners as the infected files run in-memory. In doing-so, the malicious payload is using a benign application to be built in memory, meaning that the malware does not sit running in the file system where AV scans take place. In the figure below, you can see an example of how this all plays out:


For a real-life example: in 2013, attackers exploited the executable originally developed by Fortune 50 company using this technique in a highly targeted attack. In such an attacks, the malware places a spoofed, malicious DLL file in a Windows’ WinSxS directory so that the operating system loaded the spoofed DLL instead of the legitimate file. Furthermore, because the file in-question was white-listed by hash in a public database, AV simply ignores it altogether.

In response to the growing use of DLL Side-Loading in APTs, we have developed a full paper that describes the history of DLL Side-Loading and its role in the malware and software engineering arenas which you can review here:



Write Once, Exploit Everywhere: FireEye Report Analyzes Four Widely Exploited Java Vulnerabilities

Over the last couple of decades, Java has become the lingua franca of software development, a near-universal platform that works across different operating systems and devices. With its “write once, run anywhere” mantra, Java has drawn a horde of developers looking to serve a large user base as efficiently as possible.

Cyber attackers like Java for many of the same reasons. With a wide pool of potential targets, the platform has become the vehicle of choice for quickly dispersing lucrative crimeware packages.

In our continuing mission to equip security professionals against today’s advanced cyber threats, FireEye has published a free report, “Brewing Up Trouble: Analyzing Four Widely Exploited Java Vulnerabilities.” The report outlines four commonly exploited Java vulnerabilities and maps out the step-by-step infection flow of exploits kits that leverage them.

Download the paper to learn more about these vulnerabilities:

  • CVE-2013-2471, which allows attackers to override Java’s getNumDataElements() method, leading to memory corruption.
  • CVE-2013-2465,  which involves insufficient bounds checks in the storeImageArray() function. This vulnerability is used by White Lotus and other exploit kits.
  • CVE-2012-4681,  which allows attackers to bypass security checks using the findMethod () function.
  • CVE-2013-2423, which  arises due to insufficient validation in the findStaticSetter () method, leading to Java type confusion. This vulnerability employed by RedKit and other exploits kits.

As explained in the paper, Java’s popularity among the developers and widespread use in Web browsers all but  guarantees continuing interest from threat actors.

Motivated by the profits, cyber attackers are bound to adopt more intelligent exploit kits. And these attacks will continue to mushroom as more threat actors scramble for a piece of the crimeware pie.

Operation SnowMan: DeputyDog Actor Compromises US Veterans of Foreign Wars Website

On February 11, FireEye identified a zero-day exploit (CVE-2014-0322)  being served up from the U.S. Veterans of Foreign Wars’ website (vfw[.]org). We believe the attack is a strategic Web compromise targeting American military personnel amid a paralyzing snowstorm at the U.S. Capitol in the days leading up to the Presidents Day holiday weekend. Based on infrastructure overlaps and tradecraft similarities, we believe the actors behind this campaign are associated with two previously identified campaigns (Operation DeputyDog and Operation Ephemeral Hydra).

This blog post examines the vulnerability and associated attacks, which we have dubbed “Operation SnowMan.”

Continue reading »

New IE Zero-Day Found in Watering Hole Attack

FireEye Labs has identified a new Internet Explorer (IE) zero-day exploit hosted on a breached website based in the U.S. It’s a brand new zero-day that targets IE 10 users visiting the compromised website–a classic drive-by download attack. Upon successful exploitation, this zero-day attack will download a XOR encoded payload from a remote server, decode and execute it.

This post was intended to serve as a warning to the general public. We are collaborating with the Microsoft Security team on research activities. We will continue to update this blog as new information about this threat is found.

Update: We have posted a full analysis of the attack, which we have dubbed “Operation SnowMan.”

Notes from the Field: Yahoo Malvertisement Attack

Yahoo visitors got a nasty New Year’s surprise when third-party advertisements on the site triggered drive-by malware infections. Around the end of December, Yahoo inadvertently began serving malicious ads, also known as “malvertisements,” that redirected visitors to a site hosting the Magnitude exploit kit. This resulted in drive-by malware downloads for thousands of unsuspecting users who merely visited the Yahoo site — even those who didn’t click on anything.

Yahoo quickly removed the ads and says it is working with law enforcement to investigate.

While we don’t know exactly how the malvertisers infiltrated Yahoo’s advertisement network, we are familiar with this type of attack.

This blog post examines some of technical details of the attack to help security professionals spot and combat this type of threat.

Continue reading »

CVE-2013-3346/5065 Technical Analysis

In our last post, we warned of a new Windows local privilege escalation vulnerability being used in the wild. We noted that the Windows bug (CVE-2013-5065) was exploited in conjunction with a patched Adobe Reader bug (CVE-2013-3346) to evade the Reader sandbox. CVE-2013-3346 was exploited to execute the attacker’s code in the sandbox-restricted Reader process, where CVE-2013-5065 was exploited to execute more malicious code in the Windows kernel.

In this post, we aim to describe the in-the-wild malware sample, from initial setup to unrestricted code execution.

CVE-2013-3346: Adobe Reader ToolButton Use-After-Free

CVE-2013-3346 was privately reported to ZDI by Soroush Dalili, apparently in late 2012. We could fine no public description of the vulnerability. Our conclusion that the sample from the wild is exploiting CVE-2013-3346 is based upon the following premises:

  1. The sample contains JavaScript that triggers a use-after-free condition with ToolButton objects.
  2. CVE-2013-3346 is a use-after-free condition with ToolButton objects.
  3. The Adobe Reader patch that addresses CVE-2013-3346 also stops the in-the-wild exploit.

CVE-2013-3346 Exploitation: Technical Analysis

The bug is a classic use-after-free vulnerability: Within Javascript, nesting ToolButton objects and freeing the parent from within child callbacks results in a stale reference to the freed parent. More specifically, the invalid free can be triggered as follows:

  1. Make a parent ToolButton with a callback CB
  2. Within the callback CB, make a child ToolButton with a callback CB2
  3. Within the callback CB2, free the parent ToolButton

The sample from the wild exploits the bug entirely from JavaScript. The code sets up the heap, builds ROP chains, builds shellcode, and triggers the actual bug. The only component of the attack that wasn’t implemented in JavaScript is the last-stage payload (executable file).

Continue reading »

MS Windows Local Privilege Escalation Zero-Day in The Wild

FireEye Labs has identified a new Windows local privilege escalation vulnerability in the wild. The vulnerability cannot be used for remote code execution but could allow a standard user account to execute code in the kernel. Currently, the exploit appears to only work in Windows XP.

This local privilege escalation vulnerability is used in-the-wild in conjunction with an Adobe Reader exploit that appears to target a patched vulnerability. The exploit targets Adobe Reader 9.5.4, 10.1.6, 11.0.02 and prior on Windows XP SP3. Those running the latest versions of Adobe Reader should not be affected by this exploit.

Post exploitation, the shellcode decodes a PE payload from the PDF, drops it in the temporary directory, and executes it.


The following actions will protect users from the in-the-wild PDF exploit:
1) Upgrade to the latest Adobe Reader
2) Upgrade to Microsoft Windows 7 or higher

This post was intended to serve as a warning to the generic public. We are collaborating with the Microsoft Security team on research activities. Microsoft assigned CVE-2013-5065 to this issue.

We will continue to update this blog as new information about this threat is found.

[Update]: Microsoft released security advisory 2914486 on this issue.

Exploit Proliferation: Additional Threat Groups Acquire CVE-2013-3906

Last week, we blogged about a zero-day vulnerability (CVE-2013-3906) that was being used by at least two different threat groups. Although it was the same exploit, the two groups deployed it differently and dropped very different payloads. One group, known as Hangover, engages in targeted attacks, usually, against targets in Pakistan. The second group, known as Arx, used the exploit to spread the Citadel Trojan, and we have found that they are also using the Napolar (aka Solar) malware. [1]

Looking at the time of the first known use of the exploit, we noted that the Arx group appeared to have had access to this exploit prior to the Hangover group. Subsequent research by Kaspersky has found that this exploit was used in July 2013 to spread a cross-platform malware known as Janicab. Interestingly, the Janicab samples have exactly the same CreateDate and ModifyDate as the Arx samples. However, the ZipModifyDate is different. They also contain the same embedded TIFF file (aa6d23cd23b98be964c992a1b048df6f). Continue reading »

Operation Ephemeral Hydra: IE Zero-Day Linked to DeputyDog Uses Diskless Method

Recently, we discovered a new IE zero-day exploit in the wild, which has been used in a strategic Web compromise. Specifically, the attackers inserted this zero-day exploit into a strategically important website, known to draw visitors that are likely interested in national and international security policy. We have identified relationships between the infrastructure used in this attack and that used in Operation DeputyDog. Furthermore, the attackers loaded the payload used in this attack directly into memory without first writing to disk – a technique not typically used by advanced persistent threat (APT) actors. This technique will further complicate network defenders’ ability to triage compromised systems, using traditional forensics methods.

Enter Trojan.APT.9002

On November 8, 2013 our colleagues Xiaobo Chen and Dan Caselden posted about a new Internet Explorer 0-day exploit seen in the wild. This exploit was seen used in a strategic Web compromise. The exploit chain was limited to one website. There were no iframes or redirects to external sites to pull down the shellcode payload.

Through the FireEye Dynamic Threat Intelligence (DTI) cloud, we were able to retrieve the payload dropped in the attack. This payload has been identified as a variant of Trojan.APT.9002 (aka Hydraq/McRAT variant) and runs in memory only. It does not write itself to disk, leaving little to no artifacts that can be used to identify infected endpoints. Continue reading »