The high jumper won bronze in 2008 but that result is now in doubt after 454 samples from those Games were retested.
"It's the most complete shock," said Chicherova, who went on to win gold at the 2012 Games in London.
"I can't explain how it could have happened. I was always sure what supplements and medicines I was using."
Earlier this month, the International Olympic Committee said up to 31 athletes from around the world could be banned from the Rio Olympics as a result of the retests, which were conducted using the latest scientific methods.
The Russian Olympic Committee subsequently revealed that 14 of those 31 athletes were Russian.
A Russian TV report then claimed those 14 athletes included 10 medallists, among them 33-year-old Chicherova, who is planning to defend her Olympic title at the Rio Games, which begin on 5 August.
Sports minister Vitaly Mutko admitted the news did not "look good" but said the results were "not an objective picture" of Russia's doping situation.
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Russia's athletes are already banned from international competition following allegations of state-organised doping.
But in an interview with BBC sports editor Dan Roan, Mutko said he expected the ban to be lifted for Rio because it would be "useless" for the International Association of Athletics Federations (IAAF) to continue punishing them.
He also held the IAAF partly responsible for Russia's predicament, claiming it helped cover up the positive tests.
"The priority for them [IAAF] must be the development of track and field worldwide and you cannot achieve that with punishment," he said.
"It damages hugely the reputation and image of track and field. It would decrease the popularity of the sport in Russia. Kids would not want to do it."

The appeal comes on what would have been Beyake Keita Ann's 22nd birthday.
He died in hospital three weeks after the assault by a gang of men in Attock Park on 23 August.
Police said 15 men had been questioned by detectives as part of the investigation.
More on this and other Bradford stories
Officers will be staging a reconstruction of the incident.
Det Ch Insp Ian Scott said he wanted anyone who was in the park that night to come forward.
He said: "Beyake was a young man who today should have been celebrating his 22nd birthday with family and friends.
"Instead of celebrating it with him, they will be remembering his life at what is and continues to be a very sad time for them.ã€€
"We are committed to getting justice for Beyake and his family and finding out who it was that inflicted his fatal injuries."ã€€

The 28-year-old failed to make a appearance for the Australian side after joining on a two-year deal from St Helens at the start of the season.
Turner, a title winner with Saints in 2014, did however play in the NRL All Stars game earlier this year.
"I'm excited to be returning home to the UK with Huddersfield," he said.
"Last year I took an opportunity that was given to me to head out to Canberra knowing how difficult it would be for me and my partner on the other side of the world and was keen to stick it out.
"In the last few months I have had plenty of opportunities to return home but turned those chances down."
Giants head coach Rick Stone said Turner comes in to replace Ryan Brierley who joined League One side Toronto in April.
"We have been looking to fill a gap ever since Ryan moved on and I am delighted that our patience has been rewarded with such a good acquisition," Stone said.
Turner, who played more than 100 times for Saints and also previously featured for Salford and Hull FC, joins a Huddersfield side third-from-bottom in Super League, with his deal announced after they were beaten 28-26 at Wakefield.
Olympic medallist Anna Chicherova has vowed to clear her name after learning she is one of 14 Russian athletes to have failed a doping retest.
[NEXT_CONCEPT]
Police are asking for new information about the murder of a man who was "brutally attacked" following a row during a football match in a Bradford park.
[NEXT_CONCEPT]
Huddersfield have signed Super League Grand Final-winning utility back Jordan Turner on a three-and-a-half-year deal after he was released by Canberra.