In the video, the boy, who has been identified as Abdullah in prior ISIS videos, sports long hair and wears a black sweater and military fatigue pants.
He stands behind the two men, who are kneeling, and shoots them in the back of the head in a theatrically produced video with slow motion. The boy stands over one of the bodies, fires two more times, and later raises his pistol high.
CNN cannot verify the authenticity of the video, but it appears to be the first time ISIS has shown a child carrying out an execution.
The video's title is "Uncovering an Enemy Within" and states that "enemies thought that they could dispatch spies and agents to plot against the Islamic State, but Allah disgraced their efforts and thwarted their plans."
Recruiting child soldiers
The Islamic State in Iraq and Syria is using warfare and terror in an attempt to create an Islamic state, or caliphate, across the Sunni areas of Iraq and in Syria.
ISIS has featured children as fighters before, calling them the "cubs of the caliphate," a play on words referring to how jihadis are called "lions." ISIS has encouraged foreign fighters to bring their families and has taken over schools to indoctrinate children.
In June, Human Rights Watch documented the experiences of 25 children and former child soldiers in Syria's civil war and asserted that nonstate armed groups have used children as young as 15
to fight in warfare and used others as young as 14 in support roles.
ISIS and other extreme Islamists "have specifically recruited children through free schooling campaigns that include weapons training and have given them dangerous tasks, including suicide bombing missions," the rights group said.
In earlier ISIS videos, the boy named Abdullah says that he's from Kazakhstan and wants to grow up to kill "infidels." He appears to be Asian.
ISIS has used shocking imagery of children in the past. In August, a 7-year-old Australian boy held a man's severed head reportedly in the ISIS-held town of Raqqa, Syria. The photo was posted on Twitter by his Australian father, Khaled Sharrouf, who wrote "that's my boy."
The international community condemned the incident and photograph.
Russian media: No comment
The London-based Syrian Observatory for Human Rights said Russians did infiltrate Syria in late December and made up the majority of 19 men who went to the ISIS-held area of al-Ra'i. The Observatory is an activist group opposing the Syrian government, embroiled in a civil war where ISIS has established strongholds.
The video shows the two men being questioned by someone off-screen, and they identify themselves as Mamayev Jambulat Yesenjanovich, 38, who was born near Jambul, Kazakhstan, and Ashimov Sergey Nikolayavich, 30.
Both men say they are informants for the Russian intelligence service. In the questioning of the 38-year-old man, the video states that service as "FSB," or Russian's Federal Security Service.
The Russian state security organization could not be immediately reached for comment Wednesday.
The Russian state news agency RIA reported that the FSB and the Russian embassy in Syria refused to comment on the situation.
'A good intelligence network'
On January 4, Ramzan Kadyrov, the head of the Chechen Republic, told the news agency Interfax
that Russia has an intelligence network within ISIS.
When asked whether there was an ISIS terrorism threat in Chechnya, Kadyrov stated: "There is no threat. We are scaring ourselves with ISIS. Within the ranks of hordes of terrorists, we have a good intelligence network. This allows us to track the movement of those who are of interest to us. Moreover, it allows us to send those who, even as a joke, direct the barrel towards Russia on an eternal trip with a one-way ticket."